212Essential processes in ic power units

The three essential processes in any internal combustion power unit are compression of the air charge, combustion of the fuel, and expansion of the products as completely as possible to produce mechanical work. The greater the degree of compression and expansion, and the greater the range of temperature effectively utilised, the higher will be the thermal efficiency and the lower the specific fuel consumption. These conditions apply to both piston and turbine engines. The piston engine can...

1211 Lambda sensor

This is another sensor of major importance developed by Bosch for the internal combustion engine, and first used by Volvo in 1976. Its name is derived from the fact that the Greek letter lambda, X, is used as the standard symbol for the air fuel ratio, which is the ratio of the actual mass of fuel supplied to that required for complete combustion of all the air present in the mixture. The function of this sensor, which is screwed into the exhaust manifold, is to detect departures of the air...

4223 Austin Mini Metro Suspension

The Metro suspension, Fig. 42.34, is a modified Hydragas system. All four wheels have gas springs but, because of the short wheelbase and potentially large variations in front-rear weight distribution, the front and rear springs are not interconnected. This avoids both a high frequency of pitching when lightly laden and a tail-down attitude with a heavy load of luggage at the back. As in the Mini, a twin unequal-length traverse link system is used at the front, and a trailing link actuates each...

2113Gas turbine prospects

With heavy commercial vehicles now operating at maximum loads of 44 tonnes, and powered by engines of the order of 400 bhp (300 kW), the gas turbine is worthy of consideration as a potential power unit, although the problems associated with cleaning the exhaust without penalty as regards efficiency remain to be overcome. Although the development of motorway networks worldwide, on which constant speeds of operation tend to be practicable, traffic congestion is increasingly ruling out constant...

628The Lucas CAV injection pumps

The CAV range of in-line injection pumps, which originated soon after a merger between CAV and Simms, comprises three pumps the Minimec, Majormec and Maximec. Of these, the Maximec is principally for military and railway applications and is available for four-, six-, eight- and 12-cylinder engines. All versions of the range are driven from the end remote from the governor. The maximum power outputs per cylinder obtainable with these pumps are, respectively, 40, 60 and 100. Since all three are...

1416 Some more complex valve arrangements

Where a computer-controlled catalytic system is installed, a solenoid-actuated air-switching valve is interposed between the output from the normal diverter valve and the delivery line to the exhaust manifold. When the system is operating with a cold engine, on the open-loop principle, the Standardised Diverter Valve functions exactly as described in the previous section. However, when the engine is warm and the computer control switches to closed-loop operation, the solenoid-actuated valve...

207 Zevco fuel cell for cars Europe

Zevco (Zero Emission Vehicle Company) of Ramsgate in the UK and Geel in Belgium has developed a fuel cell of the alkaline type for application to road vehicles. This type of propulsion unit is particularly suitable for vehicles operating on fixed routes, such as those used in airports, and for postal and various types of urban delivery. For three reasons a taxi was chosen for the on-road proving testing and development. First, unlike most cars, taxis are mounted on chassis and therefore are...

118 Solex MIMAT carburettor

The MIMAT is a downdraught, twin-choke carburettor, with throttles compounded to open one after the other - the throttle in the secondary choke does not start to open until that in the primary is about two-thirds open. Both chokes of course are the same diameter. This twin-choke arrangement mitigates the disadvantages of a fixed-choke carburettor, which are a tendency towards poor atmomisation at low air speeds and strangulation at high speeds. Although careful design and setting is necessary...

2116 Dualchamber versions

The main subdivisions of categories of stratified charge engines are those with single combustion chambers, as just described, and those with dual chambers. Both can be further divided into carburetted, and early and late injection. The dual-chamber versions are in general similar to indirect injection diesel engines, in that they have a small pre-chamber, generally in the cylinder head, but of course they are spark ignited. A dual-chamber engine supplied with carburetted mixture is the Honda...

62 Air blast injection

This method constituted the true diesel method as originally used in large stationary and marine engines, and involved the following features. The compression pressure was about 3450 kN m2, and the fuel was measured and delivered by a mechanical pump to the annular space behind a small conical injection valve placed in the centre of the cylinder head and arranged to open outwards. To this space was applied an air pressure of 5516 to 6895 kN m2 from air storage bottles charged by a compressor...

Servo and poweroperated and regenerative braking systems

As vehicle weight increases then the force that must be exerted on the pedal of a simple brake system to produce the maximum deceleration permitted by the road conditions also goes up, and when the weight exceeds two to three tons the force required may become greater than a man can exert. The driver must then be given some assistance in applying the brakes. This can be done in two ways (a) by using a servo mechanism which adds to the driver's effort although that effort remains a considerable...

Brakes

The operation performed in braking is the reverse of that carried out in accelerating. In the latter the heat energy of the fuel is converted into the kinetic energy of the car, whereas in the former the kinetic energy of the car is converted into heat. Again, just as when driving the car the torque of the engine produces a tractive effort at the peripheries of the driving wheels, so, when the brakes are applied the braking torque introduced at the brake drums produces a negative tractive...

283 Other arrangements of torque converters

Four arrangements of single-stage converters are shown in Figs 28.8 to 28.11. In Fig. 28.8 the reaction member R is permanently fixed, which makes it unsuitable for use in motor vehicles unless some form of direct drive is provided and the converter is emptied when the direct drive is engaged. The design shown in Fig 28.9 is widely used, being simple constructionally the one-way clutch S is sometimes placed outside the casing by providing the reaction member with a sleeve which passes through...

1019 Starting and idling enrichment devices

When the vehicle is stationary and the engine ticking over, idling, or slow running, the velocity of flow though the carburettor is such that the fuel drawn from the jets is sufficient to develop only enough power to overcome the resistance of its moving components. In this condition, the engine should be running as slowly and quietly as practicable, but be capable of being accelerated instantly, for instance for moving away from traffic lights. However, in a fixed-choke carburettor, when the...

4317Rear suspension dead axles

The considerations applying to a dead axle at the front also apply at the rear but without the complication inherent in the need to steer the wheels. However, except on some commercial front-wheel-drive special-purpose vehicles, and of course trailers, dead rear axles are rarely used. For cars, on the other hand, a particular form - the de Dion axle - is not uncommon. The de Dion axle (see Section 25.3) is most suitable for cars with a low centre of gravity, hard suspension and a long...

1012 Compensation by compound and submerged jets

One of the earliest successful methods of compensation was the Baverey compound jet illustrated in Fig. 10.4. The fuel is drawn through two jets, that at A being the main supply and the other, at that at B, the compensating jet. Originally only the compensating jet orifice was situated in the base of the float chamber, but it soon became common practice to submerge both jets. The advantage of submerged jets is that, because they are lower and therefore subjected to a weaker depression than if...

256 Variation of the tractive effort with speed

Now, since the engine is geared to the driving wheels, a particular engine speed corresponds to a particular vehicle speed, and since the tractive effort is proportional to the engine torque, the variation of the tractive effort with the variation of the vehicle speed will depend upon the variation of the engine torque with the variation of engine speed. This last relation has already been considered and a curve showing it is given in Fig. 3.7. The curve showing the relation between tractive...

4010 Rear wheel steering

For example, we have known and utilised for many decades the steering effects of leaf springs on back axles, Section 42.12. Moreover, rear wheel steering is widely used for increasing the manoeuvrability of fork lift trucks and other industrial vehicles. In 1946, Dixon and Rolt produced a prototype car, called the Crab, with rear wheel steering. By the late 1960s, ease of parking was still the aim of some major manufacturers, including Audi. In 1977, the Porsche...

711Automatic advance and retard unit

Because injection must be advanced as engine speed increases, an automatic Fig. 7.17 Diagram showing how the scroll plate movement controls the paths that the rollers take on approaching and leaving the cams advance unit is supplied for application to the DPS rotary injection pump. This unit can also incorporate a mechanism for retarding the injection when the engine is started, and then cutting out as soon as it is running. To enable the driver to maintain stable slow running in very cold...

206 Fuel cells in buses US and Canada

Between 1990 and 1995, the power density of fuel cells in general increased by a factor of seven. By the beginning of 1996, the US government provided Fig. 20.4 Four of the eight face-centred atoms of the titanium molecule (outer cube) each represent V2 of an atom of four metals in the alloy, while the remaining two are whole atoms. This is because the actual molecular structure is more complex than that shown here four of the six faces of the metallic cube each have another cube coincident...

348 An interesting cylinder head design

An outstandingly good cylinder head design is that of the Dolomite Sprint, Fig. 3.39. Since it exemplifies the best solution to many of the problems, it will be described here. It is of aluminium and has four cylinders, four valves per cylinder, and a single overhead camshaft. The exhaust valves are inclined 16 to one side of the axis of the cylinder and the inlets 19 to the other side. Their seats are in a penthouse-type combustion chamber. Since the engine, when installed, is tilted 45...

Constructional details of the engine

From the outline of the general principles in Chapter 1, and the requirements as regards balance in Chapter 2, we now turn to the details of construction, leaving engines having six or more cylinders to Chapter 4. Sleeve valve, rotary valve, and rotary piston engine constructions will then be dealt with in Chapter 5. The conventional layout described in Section 1.10 has become firmly established, despite attempts to develop for automotive applications others such as the swash-plate motor,...

2612 A fivespeed gearbox

The gearbox shown in Fig. 26.12 is an example of a mixed type of box, the first and second speeds being by sliding-mesh gears and the others by constant-mesh gears. The shaft A is coupled to the driven shaft of the clutch and has the pinion B formed integrally on it. This pinion drives the layshaft to which the gears C, D, E and F are splined. The mainshaft G is supported at the left in a roller spigot bearing housed inside the pinion B, in the centre by a ball bearing carried in an...

341Variable valve timing and the Atkinson cycle

In general, fixed valve timing is optimised either for the speed at which maximum torque is developed or to obtain good nominal power output. Applying the Atkinson cycle (Section 3.38) for controlling the engine solely by varying the valve timing entails opening the valves for periods that decrease as speed and load are reduced. Three benefits are thus obtained considerable reduction or even total elimination of blow-back into the induction system, pollution of the charge by residual exhaust...

1027 Mechanically actuated acceleration pumps

Two examples of acceleration pump mechanisms are that in the Zenith IV, Fig. 10.22 and the Stromberg DBV carburettor, Fig. 10.23. In the Zenith unit, there are two concentric springs over the pump. Both are compressed Fig. 10.22 Zenith IV carburettor, showing accelerator pump Fig. 10.22 Zenith IV carburettor, showing accelerator pump by the lever connected to the throttle control. However, the inner one, by pushing the piston down after the piston rod has been slid through the hole in its crown...

3818 Regenerative braking systems

A simple form of regenerative braking system is often employed on electric vehicles. It is necessary because the energy storage capacity of a battery of a weight and size practicable for installation in road vehicles is so small that one cannot expect to get more than 30 to 40 miles (38 to 64 km) out of it, even with regeneration of the energy that would otherwise be dissipated in braking. This type of vehicle has an electric motor and control system such that, when current is passed through...

116 Multibarrel carburettors

The performance of an engine designed to run over a wide speed range with only one carburettor is considerably improved by installing two- or four-barrel carburettors. Twin barrel should not be confused with twin carburettors, the latter of course referring to an installation comprising two separate carburettors. The latter have been used on four-cylinder engines but, because they can obviate inter-cylinder robbery of charge, as explained in Sections 13.6 and 13.7, they are of greater benefit...

2624 The Fuller twincountershaft gearbox

This provides an example of the second method of obtaining a multiplicity of ratios but also embodies a principle which enables the size of the box to be reduced. By using two layshafts (or countershafts) the tooth loads are halved and so the gears can be made only a little more than half as wide as they would have to be if only one layshaft were used. This will, however, be successful only if the torque is in fact equally divided between the two layshafts, and the way in which this is ensured...

197 Radiator construction

Copper radiators have now evolved into two types of water-tube construction, the early honeycomb or cellular construction shown in Figs 19.9 and 19.10 being obsolete. Though having certain advantages in appearance, ease of repair and smaller proportionate immobilisation by a single obstruction, the earlier types suffer from the important heat transfer defect that the ratio of metal-air to water-metal dissipating surface is practically unity instead of being many times that figure. In modern...

148 Ford EGI system for preheating catalysts

Generally, catalysts on ceramic monoliths do not become reasonably effective until they have attained a temperature of approximately 350 C, and are not fully so until a temperature of 450 C is attained. On average, two-thirds of all car journeys undertaken are less than 5 miles in length. Indeed, on a short journey, as much as 80 of the total emissions after starting with a cold engine are produced during the first 2 min, and the situation is even worse in cold climates and in urban conditions....

1716 Cetane number cetane index and diesel index

Basically, the cetane number is the percentage of cetane in a mixture of cetane (n-hexadecane) and heptamethylnonane (the latter is sometimes referred to as a-methylnaphthalene) that has the same ignition delay, generally expressed in terms of degrees of rotation of the crankshaft, as the fuel under test. There is a more precise definition but, before we come to it, a brief note on ignition delay is necessary. Ignition delay, Section 17.32, is important because, if it is too long, the whole...

433 Double transverselink suspension

A double transverse-link suspension, with a torsion-bar spring, is illustrated diagrammatically in Fig. 43.5. To eliminate wheel tilt with deflection, that is change in the camber angle 0, the two arms would have to be of equal lengths, which would place the roll centre at ground level. This, however, would have the effect of varying the track with roll, having undesirable steering effects and could also adversely affect tyre wear. By shortening the upper link it is possible to keep the track...

4210 Laminated spring details

On road vehicles, semi-elliptic springs are usually slung beneath the axles, but on cross-country vehicles, to give more ground clearance beneath the body and chassis, they may seat on top of them. In either case, the spring seating pad is generally either welded to the axle tube or is integral with it, and the spring is clamped between it and a saddle plate by either four bolts, or by two U-bolts either embracing grooves around the saddle or seating in separate stirrup pieces around the tube....

651 Filtration and system layouts

For equipment, such as tractors and other off-road vehicles, operated in extremely dusty conditions, a filter may have to be fitted over the outer end of the fuel tank vent pipe to prevent dust particles larger than about 7 m from entering it. The size of the vent needs to be severely restricted because, with the fuel swilling around in the tank, air is continuously flowing in and out. A road-going commercial vehicle, on the other hand, generally does not need a vent filter, but usually has a...

82 Perkins Prima DI engine

The alternative to reducing the number is, of course, to reduce the size of the cylinders. This had, until 1986, been impracticable for the reasons given in Section 6.12. Though, as mentioned previously, Perkins was first with its Prima engine, Ford had about a year earlier introduced a 2.5-litre DI diesel engine rated at 4000 rev min for their Transit van. Some of the disadvantages of indirect injection are outlined in Section 6.12 and the problems to which it is a solution in Section 6.18. As...

642 Lucas electronic unit injection EUI system

In the early 1980s, Lucas developed their EUI system to obtain high rates of injection,with precise timing and sharp cut-off, for satisfying emissions regulations. Pressures up to the 1500 bar needed for adequate rates of injection are virtually impracticable with the traditional in-line or distributor type pumps. This is mainly because the large spill port areas needed to obtain sharp cut-off with high flow rates would lead to cavitation erosion in the relatively long fuel delivery lines....

53Advantages and disadvantages of sleeve valves

The great advantages of the sleeve valve are silence of operation and freedom from the necessity for the periodical attention which poppet valves require, if the engine is to be kept in tune. Hence sleeve valves have been used in cars of the luxury class where silence is of primary importance. The average sleeve-valve engine has not shown quite such a good performance as its poppet valve rival in maintenance of torque at high speeds, owing chiefly to the somewhat restricted port openings...

124 Injector design

Because of the low pressures involved, pintle-type injectors lifted off their seats by the fuel pressure are impracticable for petrol injection. Most of those currently to be found in road vehicle engines are illustrated in Figs 12.3 to 12.8. All are electronically controlled and, since extreme accuracy of metering is essential, a prime requirement is a linear relationship between quantity of fuel delivered and the pulse width of the control signals. Moreover, this linearity has to be...

4212 Steering effects of leaf springs

Although leaf springs have the advantage of performing the two functions of springing and axle guidance, they have steering effects on their axles. These effects arise from two sources the first is simply by the motion they induce in the axle, and the second is attributable to the effect of this motion on the steering linkage. The motion of the axle, if it is not regulated by any other linkage, is controlled by the motion of the spring acting as if it were a solid link pivoting about the end...

1419Reduction of emissions conflicting requirements

Measures taken to reduce NOx tend to increase the quantity of particulates and HC in the exhaust, Fig. 14.20. This is primarily because, while NO is Fig. 14.20 Tests done in the late 1980s to demonstrate how NOx increases when measures are taken to reduce particulates in different types of engine Fig. 14.20 Tests done in the late 1980s to demonstrate how NOx increases when measures are taken to reduce particulates in different types of engine reduced by lowering the combustion temperature, both...

346 Multivalve heads

Three valves per head, two inlet to facilitate breathing, have been used, though not widely, for many years. A typical three-valve arrangement, with a toothed belt driven single overhead camshaft, Fig. 3.35, is that of the 1342 cm3 engine for the Rover 200 range. Although four valves per head have been virtually universal in aero engines of the reciprocating piston type since the First World War, and common in racing cars, it was not until the beginning of the nineteen-eighties that this layout...

2423 Fluid flywheel

This consists of two castings (called rotors), almost identical in form, one of which is fixed to the crankshaft of the engine and the other to the gearbox shaft. These castings are roughly circular discs in which passages XX, Fig. 24.18, are formed. Since the areas of these passages perpendicular to their centre line (XXX in the sectional view) must be kept approximately constant and since the circumferential width of the opening a is less than that of b the radial size of the opening A is...

4323 Active suspension

Conventional suspension systems, comprising spring, damper and resilient tyre, Fig. 42.1, can be termed passive they are self-contained and react automatically to the loads applied to them at the road surface. However, Fig. 43.28 The Alfa 6 rear suspension in elevation (top) and plan (bottom) Fig. 43.28 The Alfa 6 rear suspension in elevation (top) and plan (bottom) there is absolutely no active control over these reactions. An active suspension system, on the other hand, is one in which the...

637 Torque control

Modern governors are generally designed not only to control speed but also to change the shape of the torque curve. The torque control requirements of naturally aspirated and turbocharged engines differ. As the speed of a naturally aspirated engine increases, the rate of air induction tends to fall off relative to that of the fuel injected. This arises because of increases in both viscous drag and that due to obstructions such as the valves and their guides. Other factors, including thermal...

137 Crankshaft and cylinder layout in relation to valve timing

As previously indicated, an interference effect, charge robbery, arises because the inertia of, and depression in, the air flowing into two adjacent cylinders during overlapping induction phases can cause one to draw in, from the manifold or plenum chamber, some of the air that should be flowing into the other. Consequently, the filling of both cylinders is adversely affected. Charge-robbing potential decreases with engine speed but, because all cylinders have to fire within two revolutions of...

185Change of viscosity with temperature viscosity index

To meet all the conflicting requirements as regards its viscosity, a lubricant should have a high viscosity index (VI), which means that its viscosity changes little with variations in temperature. The higher the VI the less is the effect of temperature on the viscosity of the lubricant. Methods of determining VI are set out in ASTM D2270 and IP 226. Originally two reference oils were used, one derived from Pennsylvania crude and defined as having a VI of 0 at 100 C and the other, derived from...

4211 Taperleaf springs

Despite the measures taken to improve the stress distribution throughout the depth of a semi-elliptic spring, by dividing it into a multiplicity of separate leaves, the maximum stresses in each leaf still occur only adjacent to where it is supported between the adjacent leaf or leaves and its seating pad on the axle, Fig. 42.10(a). Therefore, because so much of the material remains relatively lightly stressed, such a spring is heavier than it otherwise might be. In recent years, therefore, the...

75 DPS fuel supply and distribution system

Dpa Transfer Pump

Fuel is drawn by the tansfer pump from the tank, through a sedimenter and filter, to the regulating valve 10 in Fig. 7.9. In some instances, a feed pump may be required between the sedimenter and filter. In others, a manually actuated pump may be installed after the filter, so that the system can be primed following a filter element change or if the tank has been emptied. Immediately before entering the transfer pump, the fuel passes though a fine mesh filter thimble in the upper end of the...

312 Spur or planetary type differential

Most planetary type differentials have spur instead of bevel gears, as in Fig. 31.4, and therefore are often called the spur type. The wheels A, B are splined to the driveshafts that drive the road wheels. Meshing with the wheel A is a spur pinion E1, whose teeth extend nearly across the gap between the wheels A and B. The spur pinion F1 meshes in a similar way with the wheel B, and at the centre the two pinion mesh together. The pinions are carried on pins which are supported by the ends of...

361 Crash testing

Not only have costly cars to be tested to destruction but also the equipment with which they are tested is costly too. Indeed, for test facilities alone, the investment required is about 50 million. Consequently, many manufacturers all over the world sub-contract some or all of their testing. The Motor Industry Research Association (MIRA) at Nuneaton has the advantage of being a protection frontal, lateral, dynamic roll-over. FMVSS 301 Fuel system integrity frontal, lateral, rear impacts FMVSS...

2815 Voith Diwamatic transmission

This is shown in Fig. 28.23 and is an example of a 'split-torque' transmission, the engine power being transmitted partly by a single-stage torque converter and partly by direct mechanical action through an epicyclic gear. A forward and reverse gearbox of conventional form is also employed. The converter is somewhat different from the usual arrangement in that the impeller I discharges directly into the fixed casing R whose passages lead the fluid into the driven member D. The division of the...

38Piston rings

Piston rings tax the skills mainly of the metallurgists and production engineers. The main functions of piston rings are (1) To form a pressure seal, preventing blow-by of the gases, including combustion products at high temperatures. (2) The transfer of heat from the piston to the cylinder walls. (3) Control of the flow of oil in adequate quantity to the skirt and to the rings themselves, while preventing excessive amounts from entering the combustion chamber. Fine-grain alloy cast iron has...

1215 Bosch LJetronic system

In the L-Jetronic system, Fig. 12.21, the electronic control unit performs the same function as the mixture control unit of the K system. It does this, however, by controlling the duration of opening of the solenoid-actuated valves in the injectors. The advantage of electronic control is that there are fewer mechanical components liable to wear or to stick and thus to malfunction. Moreover, ultimately, more accurate control is possible because the system can be made more easily to respond to a...

1110 Constantdepression carburettors

In Sections 10.10 and 10.11 an explanation was given as to why compensation devices and multi-jet systems are necessary with a carburettor having a choke of fixed diameter. With this type, the choke diameter in any case is a compromise if it is too small, engine performance is limited by the restriction on its breathing on the other hand, if it is too large, the accuracy of metering of the fuel and atomisation and mixing are poor at the lower end of the range. In principle, these disadvantages...

446 Spring stresses in rigid sixwheelers

The suspension systems of six-wheelers must be considered from another point of view than that of weight distribution, namely, the effect of axle or wheel movements on the springs themselves. When the springs are rigidly bolted or are pivoted by pins to the axle and are connected to the frame by pin joints, then clearly when the axles assume angular positions relatively to the frame, as indicated in Fig. 44.12, the springs will be twisted. While this twisting is unimportant in vehicles...

393 Ford Escort and Orion antilock systems

For the Ford front-wheel-drive Escort and Orion, the Lucas-Girling, low cost system is used. It has sensors for detecting wheel-lock on only the front wheels, locking of the rear wheels being initially inhibited by a pressure-limiting valve. These models have an X-split brake control system, as described in Section 38.14 so, when operating, the anti-lock system alternatively relieves and reapplies the pressure to the brake not only on the front wheel that is about to lock but also on the...

2614 BL cars overdrive fiveratio gearbox

With fuel economy now a prime requirement, most car manufacturers have turned to five-speed gearboxes with overdrive top gear and, usually, direct-drive fourth speed. Formerly, four-speed boxes were the general rule for all but the more expensive cars, some sports models, and medium weight commercial vehicles, the last-mentioned of course because of the wide range of their weights, from empty to fully laden. A particularly good five-speed design is that developed by the former British Leyland,...

125 Some other injectors

The lightweight valves in the injectors for the Bosch K- and KE-Jetronic systems, Fig. 12.6, are opened by relatively low fuel pressures (3.3 to 3.6 bar). In fact, they vibrate axially at a rate of about 1500 Hz, to atomise the fuel as it is injected continuously into the manifold. When the engine, and therefore the electric pump, is switched off, the valve is seated by its light spring. As the valve opens, the area exposed to the fuel pressure suddenly increases, allowing the fuel to gush...

723 Boost pressure and altitude compensation modules

The principal difference between these two modules is that the boost control version is based on the use of a diaphragm type actuator while that for altitude control has an aneroid instead. Consequently, it is necessary here to describe only the boost control unit, Fig. 7.52. Fig. 7.51 For exercising negative torque control, a torque control lever entirely different from that in Fig. 7.50 is needed Fig. 7.51 For exercising negative torque control, a torque control lever entirely different from...

410 Rover 2326litre E series engines

In this design, the aim has been to reduce the number of components to a minimum consistent with the achievement of a high level of performance and reliability. The alternative swept volumes have been obtained by the use of crankshafts having different throws. Consequently, the bore is 81 mm for both, while the strokes are 76 mm for the 2350 cm3 version and 84 mm for the 2597 cm3 unit. Their compression ratios are common at 9.25 1, the pistons having dimensions different from their...

92 Reverseflow scavenge DKW engine

An interesting and successful example of the three-port engine using 'reverse-flow' or 'inverted' scavenge is the German DKW small car engine. This is a twin cylinder unit of 76 mm bore and 76 mm stroke, using crankcase displacement, but having twin transfer ports, one each side of the exhaust port, and imparting a tangential and upward flow to the entering charge. The piston deflector is dispensed with, thus eliminating pressure and inertia tilt due to lack of symmetry - a source of two-stroke...

122 Effect of supercharging on bmep and power

Figure 1.9 illustrates two aspects of supercharging and its effect on bmep (or torque) and power. The full lines represent the performance curves of an unblown engine with a somewhat steeply falling bmep characteristic. The broken lines (a) 1000 2000 3000 4000 5000 Speed-rev min 1000 2000 3000 4000 5000 Speed-rev min Fig. 1.7 Typical performance curves for an overhead camshaft, spark-ignition engine. High speeds are obtainable with the ohc layout Fig. 1.8 Performance curves of a diesel engine....

4311 Slider or pillar type

Lancia were probably the first to introduce this type of suspension, which has been used for many years too on Morgan cars. The principle is illustrated in Fig. 43.18, in which, for steering, the stub axle A, on pillar B, swivels in plain bearings in the housing C for the coil spring D. Broulhiet produced a similar suspension but with the lower end of the pillar carried in bearings, for accommodating steering motions, in the end of a rigid transverse member secured to the frame. The slider...

131 Mixture distribution and manifold pressure

Distribution of the mixture uniformly as regards both quantity and quality to each of the cylinders was the overriding design consideration so long as either carburettors or throttle barrel injection were used. However, on diesel and port injected spark ignition engines, the fuel distribution is taken care of by the injection equipment, so the manifold is left with only the air distribution function. With single-barrel carburettors on four-cylinder engines, manifold layouts such as those in...

22 Balance of reciprocating parts

The movement of the piston backwards and forwards in the cylinder is known as a reciprocating movement as opposed to the rotative movement of the crankshaft, flywheel, etc. The reciprocating parts of a motor engine are the piston, gudgeon pin and as much of the connecting rod as may be considered to move in a straight line with the piston (usually about one-third of the connecting rod is regarded as reciprocating, the remainder, including the big end, being considered as a revolving mass). Now...

191 Temperature control

There are broadly two methods of regulation in use, the first being practically universal in automobile practice (1) Control over water flow by means of a thermostat valve. (2) Control over air flow by means of radiator shutters actuated either manually or automatically by a thermostatic device. The thermostat consists of a concertina or bellows-like vessel of thin metal, similar to those employed in the aneroid barometer but filled with a suitable liquid. In some cases expansion is magnified...

1417 Vapour collection and canister purge systems

Carbon-filled canisters for storing vapours emitted from fuel tanks and float chambers are of either the open- or closed-bottom type. The filter in the base of the open-bottom type, Fig. 14.15 has to be changed regularly, generally every 24 months or 30 000 miles. On the other hand, the purge air for the closed-bottom type, Fig, 14.16, is drawn through the engine air intake before Very high manifold vacuum from Decel Atmospheric bleed Manifold vacuum Fig. 14.12 The Rochester Normal Diverter...

424 Dampers in practice

A characteristic common to all telescopic dampers is that, as the piston moves into the cylinder, its whole area is effective in transmitting the load, and thus pressurising, the fluid but, as it moves outwards, the effective area of the piston is reduced to that of the annulus between its periphery and that of the piston rod. If equal damping is required in both directions, therefore, some compensation is obtained by adjusting, to a different value for each direction of flow, the pressures at...

4216 Rubber springs

Various forms of rubber springs are used, mainly for commercial vehicles. They have been employed in passenger-carrying vehicles too, but the precise control of ride essential for comfort is difficult to achieve with such springs. A reasonably successful system was that used on the first Minis introduced by BMC. This had rubber springs similar to those in the Hydrolastic system described in Section 42.21, but each actuated directly by a rod attached to its centre, and of course without the...

398 Braking force coefficient and slip factor

If the brakes are fully applied, the retarding force rises rapidly to a maximum and then, if the wheels lock and the vehicle therefore slides, falls off initially progressively but almost immediately followed by a rapid drop to a low level although not to zero. During sliding, the coefficient of friction between the tyre and road is therefore significantly lower than that when the wheel is rolling. Where a film of water covers the road, aquaplaning can occur, Section 36.5, resulting in loss of...

304 Constantvelocity joints

The Hooke's type of universal joint suffers from a disadvantage which is obviated in some other types of joint. It is that supposing one of the shafts connected by a Hooke's joint is revolving at an absolutely constant speed then the other shaft will not revolve at a constant speed but with a speed that is, during two parts of each revolution, slightly greater and, during the other two parts of the revolution, slightly less than the constant speed of the first shaft. The magnitude of this...

648 Components of the Bosch system

The ECU is served by sensors as follows temperature and mass flow of the air passing through the intake filter pressure of the fuel in the rail engine speed and crank angle, which can be sensed from teeth on the rim of the flywheel a sensor in the throttle pedal unit transmits signals indicting throttle position and rate of change of position and another senses the temperature of the coolant in the engine. Illustrated in Fig. 6.58 is the fuel lift pump, which Bosch term the pre-supply pump. It...

620Pintaux nozzle

The term Pintaux is derived from the words pintle and auxiliary jet. This type of nozzle was developed jointly by CAV Ltd and Ricardo & Co. Engineers (1927) Ltd, and is applicable only to the Ricardo Comet type cylinder head. It was designed primarily to enable cold starting to be obtained without the use of heater plugs. With the normal type of pintle nozzle the spray is coaxial with the injector, and the direction of injection found most advantageous for all-round engine performance is...

296 Van Doorne Transmissive BV steel CVT

The Van Doorne Transmatic continuously variable transmission (CVT), further developed by Fiat and Ford and adapted for the Uno and Fiesta models in 1987, is similar in principle to the single-belt Variomatic but is much more compact and has a single segmented metal drive-belt, Figs 29.12 and 29.13. Again the pulley ratio spread is about 4 1 but the maximum overall ratio is only about 25 1. This is for an experimental installation in the Fiat Strada. From the illustration it can be seen that it...

1325 The Helmholtz resonator in combination with tuned pipes

A naturally aspirated application has been explored in detail, by Shimamoto et al., in Vol. 30, No. 259, 1987, of the JSME. A diagrammatic representation of the induction system used for this work is shown in Fig. 13.35. The effects of varying the geometry of the resonator are shown in Fig. 13.36, which illustrates the calculated results obtained by these authors when applying the Helmholtz principle to a single-cylinder engine. Diagram (a) shows that increasing the diameter of the neck of the...

113 Zenith IZ Carburettors

Each carburettor in the IZ series, Fig. 10.28, has an offset manual strangler, for cold starting, a prolonged-action-type accelerator pump, a depression-actuated economy device and volume control of idle mixture. Other refinements include a filter for the slow running tube, and jets and passages designed for the avoidance of fouling by foreign matter in the fuel. For starting from cold, operation of the choke control closes the strangler flap A. Simultaneously, a cam interconnection opens the...

374Types of brake

Brakes may be classified into three groups as follows The last two types are, in practice, confined to heavy vehicles and are not used in cars. The principle of the fluid brakes is that a chamber has an impeller inside it that is rotated by the motion of the road wheels so that if the chamber is filled with fluid, usually water, a churning action occurs and kinetic energy is converted into heat thereby providing a braking effort. To dissipate the heat the water may be circulated through a...

4222 Moulton Hydragas suspension

The Moulton Hydragas suspension, Fig. 42.21, superseded the Hydrolastic system on the BL car models. Moreover, since September 1977, its use has not been restricted, as it was by original agreement, solely to this vehicle manufacturer. Now, a constant volume of nitrogen gas has replaced the rubber springs of the Hydrolastic system. The spring unit, Fig. 42.32, is manufactured for Moulton Developments Ltd by Dunlop. It comprises a fabricated pressed-steel container, divided into three chambers,...

91 Threeport twostroke engine

Figure 9.1 shows in simple diagram-form the Day three-port engine. The exhaust port is shown at E, this being uncovered by the piston after completion of about 80 of its stroke. The transfer port T, through which the charge is pumped from the crankcase, opens slightly later than the exhaust port, as shown in 1, to reduce the risk of hot exhaust gas passing into the crankcase and igniting the new charge. It follows that the transfer port is closed by the rising piston slightly before the exhaust...

2811 Borg Warner Models 45 and 55 transmissions

The demands for increasing fuel economy have tended to expand the market for cars having smaller engines. Consequently it is in this area that manufacturers of automatic transmissions must look for volume sales. This led to the introduction by Borg-Warner of a transmission specifically designed for cars in the 1- to 2-litre categories, as opposed to the 1.5- to 3-litre range associated with the Models 35, 65 and 66. The Model 45 has four speeds and the ratio spread between top and bottom gears...

641 Unit injection

In a unit injection system, each cylinder has its own combined injection pump and nozzle. Consequently, there are no long, high pressure lines from a separate pump to the injectors, so the associated compressibility and wave problems are avoided and very high injection pressures become practicable. With high injection pressures, air swirl can be reduced. In turn, this reduces both the energy consumed in producing swirl and the heat loss to coolant. Unit injection offers many advantages. A...

616Evolution of the Perkins range of diesel engines

Perkins Ltd was acquired by Massey Ferguson and, in 1984, by Rolls-Royce Diesel. In 1986, Massey Ferguson changed its name to Varity Corporation and, in the same year, Perkins acquired L. Gardener & Sons. Ten years later, in 1996, Perkins changed its name to Varity Perkins and merged with Lucas Industries under a new UK holding company called Lucas Varity plc. Perkins introduced their Aeroflow indirect injection system prior to the Second World War. This had a pre-chamber in...

716 DPC boost controller

If a boost controller, Fig. 7.34, is fitted to the DPC pumps, a modified fuel delivery carriage must be fitted. A wedge-shaped profile on the roller shoes, Fig. 7.35, is substituted for the tongue and slot arrangement of the other pumps, for obtaining excess fuel for starting. At cranking speeds, because the excess fuel valve is closed, the transfer pressure is cut off from the actuator pistons. In the naturally aspirated version, these pistons are the excess fuel delivery pistons, 4 in Fig....

351 Camshaft drive

Whatever the type of valve used it is necessary in the four-stroke engine to drive it from a camshaft which runs at half the speed of the crankshaft, as each valve is required to function only once in two revolutions of the crankshaft. The necessary gearing for this purpose is placed, with few exceptions, at the front of the engine, that is, at the end remote from the flywheel and clutch. The camshaft or camshafts may be driven by gears, chains or toothed belts, while a few overhead camshafts...

1113 Zenith Stromberg CD and CDS carburettors

The design of the Stromberg carburettors is basically similar to that of the SU types, but they differ structurally, as can be seen from Fig. 11.26. Among the major differences is the use in the Stromberg units of a diaphragm-, instead of piston-actuated, air valve. The concentric float chamber beneath the jet assembly is a feature of all the current Zenith-Stromberg designs. On the CD carburettor, provision for cold starting is as follows a semi- cylindrical bar seats in a groove across the...

448 Scammell Routeman

Many of the principles described in this book are exemplified in the Scammell Routeman and Constructor 8 tandem drive bogie, Fig. 44.18. The drive is taken by the propeller shaft to a four-pinion, lockable, inter-axle differential unit in the top of the final-drive casing of the front axle, and then split two ways one is through a pair of spur gears down to the final drive pinion of the front axle, and the other straight through to the rear, through a short propeller shaft, to the trailing...

649 Injectors

Injection is controlled by an electromagnetically actuated valve housed within Fig. 6.59 The high pressure pump is actuated by an eccentric with a ring type follower which does not rotate. A tappet beneath each plunger seats on each of three flats spaced 120 around the periphery of the ring. Calibrated restrictors, the function of which is to damp out pulsations in the flow, can be selected to suit the engine to which the pump is to be fitted Fig. 6.59 The high pressure pump is actuated by an...

192 Waxelement thermostats

Thermostats of the wax-element type are incorporated in most pressurised cooling systems. Western-Thomson Controls Ltd of Reading were the first to introduce this type of unit into the UK, for the British diesel and gasoline engine manufacturers. The waxes used are broadly in the microcrystalline group which covers the higher melting point range of paraffin waxes. In many cases the wax is mixed with a very finely divided copper to increase the thermal conductivity of the charge as a whole. This...

4315 Torque reaction and axle guidance

Methods that have been used to obviate torque-reaction effects and for axle guidance include the provision of a torque-reaction tube coaxial with the propeller shaft and attached at its front end to the vehicle structure or the gearbox casing and at its rear end to the nose of the differential gear carrier. Alternatively, if a torque-reaction rod as described in Secton 35.8 is used, the reaction point, at its forward end, can be offset to the right of the vehicle so that the lift due to the...

643 Penske Detroit Diesel electronic unit injection

The injection unit of the electronically controlled version of the GM unit injection system Detroit Diesel Electronic Control (DDEC I) introduced in 1984 was, because of the incorporation of a solenoid, rather bulky. However, an improved, second generation version (DDEC II) went into production in 1988. An electronic control module (ECM) for injection control monitors some of the sensors that send signals to the ECM for the engine and sends command pulses directly to the solenoids in the...

4115 Manufacture

A Michelin manufacturing process is illustrated diagrammatically in Fig. 41.18. First, the raw rubbers, both natural and synthetic, are removed from their bales and fed individually, according to type, into a premastication machine from which they are delivered into what is termed a batch box. Here the various compounding materials are added. The materials in the batch box are then fed into a Banbury mixing machine, whence the rubber mix is delivered to a mill for forming into sheet material....

285 Torque converter performance

How torque converter performance should be matched to engine performance depends on the type of vehicle. For instance, in a family saloon the emphasis might be placed on attaining a high top speed whereas, for sports cars, high torque at low speed, for good acceleration from take-off, might be more desirable. The latter was the requirement for the Porsche Carrera 2, described in detail in Section 28.9, which exemplifies the problems and their solutions. In this instance, to obtain the desired...

1318Harmonics of standing waves

In addition to the standing wave at the fundamental frequency, harmonics are generated too by the initial impulse, Fig. 13.26, so a number of modes of vibration, superimposed on each other, occur simultaneously. Consequently, the initial reflection at the fundamental frequency is accompanied by a ripple of reflections at the smaller wavelengths of the overtone frequencies. The successive reflected pulses are of progressively smaller amplitudes owing to attenuation by viscous friction and...

121 Torque curve

If a suitable scale is applied, the bmep curve becomes a 'torque' curve for the engine, that is, it represents the value, at different speeds, of the mean torque developed at the clutch under full throttle conditions - for there is a direct connection between the bmep and the torque, which depends only on the number and dimensions of the cylinders, that is, on the total swept volume of the engine. This relationship is arrived at as follows If there are n cylinders, the total work done in the...

3912 Wheels on one side on ice and on the other on tarmac

Another special feature of the Bosch systems is compensation for the yawing effect that occurs if, for example, the two nearside wheels are on mud or ice and the two offside on tarmac, or vice versa. This is a yawing moment delay system, abbreviated by Bosch to GMA. When the brakes are applied, the braking effect on the two wheels on the tarmac is, of course, considerably greater than that of the two on the slippery side, and therefore causes a pronounced tendency to yaw. The effect is more...

4012 The Nissan Super HICAS system

The latest version of the Nissan system, Fig. 40.16, is a good example of how the principles of rear wheel steering are applied in practice. Essentially it comprises an electronic control unit (ECU), which controls a solenoid valve, a hydraulic pump and a power cylinder. An optical sensor mounted on the steering column transmits to the ECU signals representing steering direction and angle, and the rate of change of steering angle, and it receives signals representing vehicle speed from an...

915 GM twostroke diesel

For automotive applications, General Motors offer their 53 and some of their Fig. 9.12 Foden ci engine performance curves Fig. 9.12 Foden ci engine performance curves Fig. 9.13 External view of Foden two-stroke ci engine Fig. 9.13 External view of Foden two-stroke ci engine 71 and 92 Series two-stroke diesels, these figures representing, in each instance, the capacity (in3) of one cylinder. The 53 Series are available as three- and four-cylinder in-line, and V6 units, and the 71 Series as...

291 AP semiautomatic gearbox

This is a four-speed and reverse gearbox in which bevel gears are used as ordinary gearing for some of the ratios and as epicyclic trains for the other ratios. It incorporates a single-stage torque converter whose reaction member is held by a one-way clutch up to the change-over point. The automatic changes are controlled by the speed of the vehicle through a governor driven by the output shaft of the box and by the position of the accelerator pedal. The selector lever has seven positions...

2626Multispeed splitter gearbox

A multi-speed splitter gearbox termed the 'Twin Splitter' was introduced by Eaton in 1985. Its gear shift lever is in an H-gate and, at each of its four stations, a three-position splitter switch near the top end of that lever can be used so that, in addition to the ratio into which the main box was initially shifted, two more can be obtained. The driver preselects the splitter ratios, and therefore does not need to use the clutch, except for starting and stopping. It was termed the Twin...

293 Ricardo ALT automatic transmission

Late in 1987, the Ricardo Automatic Layshaft Transmission (ALT) unit, Fig. 29.7, was announced. It was designed by Peter Windsor-Smith and developed by Ricardo Consulting Engineers. Peter Windsor-Smith also played a major part in the design and development of the Maxwell transmission for buses, which is described in detail in Section 29.7. Although the ALT transmission is being developed, in the first instance, for cars, it has potential also for heavy duty applications. 0 10 20 30 40 50 60 70...