EP0253856A1

EP0253856A1 - Drive system for supercharged internal combustion engines

Info

Publication number: EP0253856A1
Application number: EP87900796A
Authority: EP
Inventors: Günter Mehnert
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-01-20
Filing date: 1987-01-15
Publication date: 1988-01-27
Also published as: WO1987004490A1; DE3611171C2; US4825839A; DE3611171A1

Abstract

Système de transmission, notamment pour véhicules à moteur etc, pourvus d'un moteur à combustion interne classique, avec au moins un train d'engrenages planétaires et un système permettant de compresser mécaniquement le moteur et comportant un compresseur volumétrique, une chambre de dépression située en amont et une chambre de suralimentation située en aval, lesquelles sont reliées l'une à l'autre par des passages de retour et des soupapes d'étranglement. La transmission de puissance, la variation de la vitesse de rotation et la suralimentation du moteur sont effectuées pendant le fonctionnement réel par l'étranglement de l'écoulement d'air, et de ce fait le compresseur entraîné par l'intermédiaire de la boîte de transfert spécifique au système, et jouant le rôle d'un organe de réaction, retransmet la puissance à ladite boîte de transfert et commande ainsi automatiquement le couple de sortie ou le régime de sortie, tandis que d'autre part, en tant que compresseur, il délivre de l'air de suralimentation. La dépression statique dans la chambre de dépressurisation du côté aspiration permet un refroidissement autonome du système. Des passages de retour entre les chambres de pression permettent de maintenir, par exemple, le régime de marche à vide. Afin de renforcer le couple, un ou plusieurs étages réducteurs mécaniques sont utilisés en particulier avec des trains planétaires, avec superposition en phase des étages réducteurs et changement de phases automatiques.Transmission system, in particular for motor vehicles, etc., provided with a conventional internal combustion engine, with at least one planetary gear train and a system for mechanically compressing the engine and comprising a positive-displacement compressor, a vacuum chamber located upstream and a downstream boost chamber, which are connected to each other by return passages and throttle valves. Power transmission, speed variation and engine supercharging are effected during actual operation by throttling the air flow, and thereby the compressor driven through the gearbox. system-specific transfer, and playing the role of a reaction member, transmits the power back to said transfer case and thus automatically controls the output torque or the output speed, while on the other hand, as a compressor, it delivers charge air. Static negative pressure in the vacuum chamber on the suction side allows autonomous cooling of the system. Return passages between the pressure chambers make it possible to maintain, for example, the idling speed. In order to reinforce the torque, one or more mechanical reduction stages are used in particular with planetary gears, with phase superposition of the reduction stages and automatic phase change.

Description

Drive system

description

The invention relates to a drive system for systems operated with an internal combustion engine, for example motor vehicles, with control and regulating elements for setting and maintaining predeterminable operating states, with a mechanical compressor of the displacer type, with a transmission with which the driving force of the engine in two components is distributable, one of the components being transferable to the output shaft of the system and being drivable with the other component of the compressor and the compressor sucking in and compressing air for charging the engine on the one hand and transferring power back to the transmission on the other hand and the output speed steplessly by means of throttle valves is adjustable.

Such drive systems, in particular with the listed components, are known and have been tried and tested in many variations. This applies to continuously variable transmission types as well as to the various processes for engine fertilizer However, each of the known designs also has specific disadvantages.

Continuously variable transmissions, with the advantage, for example, of keeping the range of the maximum drive torque or the minimum fuel consumption permanently usable, face the fundamental problem that a change in the speed ratio of two shafts is principally only possible with a temporary or permanent partial cancellation of the Power transmission between them is possible. The form and time course of the system-related slip in the case of translation changes ultimately also result in the specific disadvantages of the mechanical and hydraulic types and designs of continuously variable transmissions according to the prior art, be they defined or undefined slip intervals of a mechanical or hydraulic type. Also pneumatic transmissions were easy to insert into this outline.

With compressed air, special compressed air gearboxes, for example for tools or for hoists, which are driven with compressed air have become known. They play no role for drive systems with internal combustion engines. On the other hand, a pneumatic transmission with several propellers, a turbine and circulating air flow for power transmission is proposed with DE-OS 1 945 905. With undefined, permanent slip, however, its efficiency and maximum transmissible torque are low. Furthermore, for example in DE-PS 920 220 an assembly is proposed which generates compressed air for charging the engine with the purpose of increasing the air throughput in the combustion chambers and thus increasing the output or reducing the fuel consumption. The use of such units, however, also has specific disadvantages, such as mechanical loaders with compressors of the displacer type, directly driven by the crankshaft, branch off a relatively high part of the useful power and exhaust gas loaders, for example pressure wave and

Turbo-chargers, which are operated with the energy of the exhaust gas, work under considerable thermal stress and achieve their effect in a manner that is strongly dependent on the engine speed. All known charger systems have in common that they consume energy and are operated independently of the power transmission. The problem of drive systems with internal combustion engines of converting the limited range of the cheapest engine speed to a larger speed range of the drive shaft is not addressed.

The invention has for its object to integrate gearboxes and loaders so that they complement each other in their effect, the disadvantages of the known continuously variable transmission types to be avoided and the designed drive system compared to the known systems with comparable efficiency easier to set up and adjust should be. This object is achieved in that the compressor has an overpressure chamber on the engine side and a vacuum chamber on the intake side and the vacuum chamber has a throttle valve, that the overpressure chamber and the vacuum chamber are connected to one another in parallel with their conveying path via at least one return flow channel with a throttle valve With the help of another throttle valve, part of the compressor drive torque is used to generate negative pressure in the negative pressure chamber and a pneumatic device transmits a retroactive torque to the output shaft, this retroactive torque being proportional to the pressure difference between the pressure in the pressure chamber and in the vacuum chamber.

These measures create a drive system consisting of power transmission, speed change and air compression for supercharging the engine, which can also be provided with system-specific cooling, takes place in a mechanically and pneumatically acting functional unit and can be steplessly controlled using simple throttle valves.

Further advantageous measures are described in the subclaims. The invention is illustrated in the accompanying drawing and is described in more detail below; it shows:

Figure 1 shows the structure of the action of the drive system. 2 shows a preferred embodiment of the system-specific transfer case as a system component in the simplest form;

3 shows the structure of the pneumatic device and its interaction with the system component shown in FIG. 2, the mechanical force flow being represented by double lines, the air flow by single lines and the fuel and exhaust gas flow by dash-dot lines;

Fig. 4 is a schematic representation of a three-stage embodiment for a switchable torque amplification with superposition of the stages and automatic phase change, as an extension of the system component shown in Fig. 2, in interaction with the system component shown in Fig. 3, with drive on one Sun gear and output to the reverse gear, not shown, from the associated planetary web.

The system component shown in FIG. 1 is a conventional internal combustion engine as a drive source, with fuel and air supply. According to the invention, the required air can be conveyed into the combustion chambers in various ways, depending on the structural design and use of the vehicle, namely via the system-specific compressor of the pneumatic device 3 and only above or in addition, in bypass operation, via a suction valve 5 from the outside or additionally or exclusively via a further charger 4, which is advantageously driven by the system component 2.

Other designs in which the engine is charged via a separate device or omitted entirely are also within the scope of the invention, provided that they contain a subsystem of the type 2-3.

The rotational energy of the crankshaft is first transferred to the system component 2 in a form-fitting manner. The system component 2, consisting of at least one transfer case, can also be used in various designs. In Fig. 2, a simple epicyclic gear transmission with spur gears and an internally toothed wheel is shown schematically.

In this case, the drive takes place via the planet web 21. The planet gears thus distribute the driving force into a component that is available via the internally toothed wheel 23, for example for the output, and into a component that via the sun gear 22 onto the Device 3 acts.

In principle, the reverse distribution is also possible. As far as constructively possible, however, it is advantageous to run the higher speed via the inner central wheel. The Kinematics of the planetary gearbox is known: Let q be the (variable) ratio of the angular velocities w (22) to w (21). Then there is exactly one ratio q * with q *> 1 for each size ratio of the gearwheels in engagement such that the driven gear 23 stands still (idling constellation). At q = 1, ie in the case w (22) = w (21), the input and output speeds are the same (direct translation).

With the help of system component 3, this ratio q can be changed continuously during operation and set to the optimum value. A clutch as starting or shifting aid is therefore not required.

The system component 3 shown in FIG. 3 consists of at least one mechanical compressor 32 with a displacement effect, preferably a Roots loader or a half-roller compressor, with a special seal against penetrating oil, and an upstream vacuum chamber 31 on the intake side , a downstream pressure chamber 33 on the engine side as well as return flow channels 34 and the associated throttle valves D1, D2, D3.

With this simple structure, supplemented by control devices, acting on the valves D1, D2, D3, the system is technically functional. In principle, components 2 and 3 act as pneumatically controllable superposition gears with particularly low friction losses and with partial recovery of the energy used to change the speed. On the other hand, the combination can also be viewed as a device for mechanically charging the engine with the side effect of a stepless change in the speed ratio during power transmission.

Which aspect dominates depends above all on the intended use or the situation of the driven vehicle. For example, if the vehicle is to be accelerated at a constant drive speed, in particular at maximum engine torque, the angular velocity w (23) must be increased by an amount Δ w (23)> 0. According to the invention, the result at w (21) = const.> 0 by simply reducing the mass flow

achieved on the throttle valves D1 or D2. The backflow valves D3 are mainly needed for idling and part-load operation; they are closed during the acceleration process. For the air mass that can flow in per unit time, for example through valve D1, there is a maximum value according to the flow theory (with a monotonously tapering nozzle) with the relationship in which the outlet cross section of the nozzle at D1 and p the maximum possible value of current density is with the air density and the

Flow velocity u. is to be regarded as a constant specific for air for the current flow process; because Y applies

with '~ -maximum inflow speed- speed, as well = Density of outside air, = Outside temperature, , with = spec. Heat (air), / (Cf. Becker, Technical Fluid Dynamics, Teubner-Verlag

1977, pages 134-145). It follows that the maximum current density , regardless of negative pressure, with, ie can be varied with the throttle valve D1

The relationships also apply analogously to the overpressure chamber 33, but here also as a function of the variable density and temperature. When the throttle valves D1 or D2 are reduced, the delivery volume of the compressor (32) is steadily reduced. A vacuum is created in the intake -sided vacuum chamber 31 and an overpressure in the engine-side pressure chamber 33, namely acts on the Rotary piston of the compressor 32 total pressure

The compressive force F _p = Δ P. A (32) against the cross-sectional area A of the compressor 32, and the angular velocity w (32) is reduced by the amount Δ w (32).

The mechanical coupling of the rotary piston axes with the epicyclic gear mechanism 2 therefore necessarily results in a reduction or limitation of the sun gear speed w (22); and finally, via the planet gears, the drive is transferred to the internally toothed wheel (23), depending on the valve position D1, D2, D3 with the output speed 0 up to the ratio 1: 1 or above.

In this simple design, as described with system component 2, the idling while the engine is running results from the kinematics of the planetary gearbox, as a limit case of the relation q = w (22) / w (21), with w (22) > w (21)>0; and a reversing gear is provided for reversing the direction of the drive, preferably a downstream planetary gear reversing gear with switchable locking devices. The qualitative relationship is: w (21)> 0 → w (22) hw (32) → - m (3);

Δ a (3) → Δm (3) → Δp (3) → FP ₍₃₎ → Δw (32);

Δ w (32) → Δ w (22) → Δw (23)> 0. The machine works with a permanent but defined one

Slip and with little friction. This is their specific advantage. The full drive torque can be transmitted in each phase.

The thermals of the system always remain adjustable; because the vacuum chamber 31 serves, among other things. as a cooling device against the temperature increase in the pressure chamber 33 when the engine is charging. This autonomous cooling is also advantageous when there is little external cooling, e.g. at low vehicle speed. In addition, both this negative pressure and the excess pressure of the air chamber 33 can be used for servo units outside the drive system.

The boost pressure p ₃ ≤ P ₂ arises depending on the speed of the compressor 32 and the valve setting D1, D2, D3. Determining and controlling the optimal opening of the individual valves depending on the driving situation is technically easy, in particular with the help of a microprocessor and by expanding an already existing motor electronics

The efficiency of the drive system is only determined by affects the heat flow between the air chambers 33 and 31 negatively - more precisely: by the part of the heat released in 33 that cannot be dissipated to the chamber 31. Through a suitable shape and arrangement of the pressure chambers 31 and 33 shown schematically next to one another in FIG. 3, in particular through a spatial penetration, for example with a number of pressure-resistant tubes integrated in the air flow, this part can be additionally restricted by constructional means.

The overall construction effort remains low. Since the delivery rate of the system-specific compressor does not necessarily have to be maximized, its speed, size and gap losses remain uncritical. Independently of this, high-performance vehicles can be operated with an additional, separate engine charge.

Mechanical reduction stages, in particular planetary gear sets, which are known in this function, for example with brakes and clutches, can be activated to amplify the drive torque.

However, an arrangement of planetary gear sets can also be used for the drive system according to the invention, which - as an extension of the system component 2 - can advantageously be combined with the pneumatic device 3 and which does not have any for changing the individual torque phases Switching elements such as brakes, clutches and the like, and no separate switching control is required. Such an arrangement is essentially realized with one or more coaxially engaged group gears, the ring gear of which is supported on the housing via a freewheel, preferably according to the diagram shown in FIG. 4.

The individual planetary gear sets are connected to the pneumatic device 3 via the sun gear 442 of the system-specific transfer case 44 and via a hollow shaft. The drive through the crankshaft of the engine is guided via the sun gear 421 into the collective gear 42, which is coupled to the preceding collective gear 41.

The ring gear 413 is blocked by the freewheel 461 against reverse running, so that the drive is initially passed on only via the planetary web 422, and is reduced.

The type of coupling and the constructively selectable design of the planetary gear sets 41 and 42 influence the degree of reduction and the adjustment range of the individual reduction phases. The wheel 422 conducts the correspondingly increased force via the sun gear 431 into a further collective gear 43, the ring gear 433 of which likewise cannot avoid the drive torque, due to the freewheel 463 The resulting, in turn, increased force is thus transmitted to the planetary web 441 of the transfer case 44 and to the sun gear 451 of the inner gear set 45. The power transmission takes place at idle as long as the hollow 453 and the ring gear 443 firmly connected to it can move backwards.

In an operating state in which the engine speed is constant, with the braking of the sun gear 442 by the pneumatic device 3, the reverse rotation of the ring gears 443, 453 is also throttled, with the result that the increased drive torque is finally 441 to the output gear 452 and the reversing gear, not shown, is transmitted. As soon as the angular velocity w (443) = 0, the freewheel 464 switches on and the ring gear 433 is carried along. The output speed is increased further.

When the sun wheel 442 is braked further - synchronously with the acceleration of the vehicle - from the point at which w (433) = w (423)> 0, the freewheel 462 then switched on and the planetary gear set 42 are used the ring gear 413 released from the lock of the freewheel 461 and also driven.

In the case w (441) = w (442) there is also w (441) = w (443), and because of the now active connection of all external ones Central wheels is thus also w (421) = w (423) etc., analogously for all wheels; ie all planetary gear sets rotate like a closed shaft (ratio 1: 1).

In principle, any number of reduction stages, in particular fewer reduction stages, can be combined. A 2-stage embodiment results e.g. 4 without the planetary gear sets 41 and 42. More planetary gear sets are required in each case than when using brakes and clutches, i.e. with alternative switching of individual stages, but for this - with the exception of the sun gear 442, which drives the compressor 32 - the speed of all central gears, especially the outer, most massive central gears, and the planet carrier up to the ratio 1: 1 is always lower than that Engine speed; the relative speed of the individual wheels disappears in the course of vehicle acceleration, and the activation or deactivation of the individual reduction stages takes place autonomously, i.e. without external aids, solely depending on the speed ratio between the crankshaft and compressor, depending on the position of the throttle valves D1, D2, D3.

The phase-wise superimposition of the individual reduction stages also has the advantage over the switching of alternative stages that a phase change additionally activates or deactivates a stage with a constant, in particular with a constant course of the engine speed is possible.

Regardless of the torque gain, another important point for use in practice has to be considered. The drive of the compressor 32 via a transfer case, e.g. 2 or 44, assumes the braking effect of the output; and it is always there when the vehicle is to be driven. However, if the vehicle is to be braked, especially downhill, the drive and output switch sides. In order to still be able to use the braking force of the engine during operation and at a standstill, the evasive movement of the gearbox must be limited in this case by constructional means. The easiest way to do this is with a special freewheel, e.g. 47, which prevents the advance of the outer central wheels and thus the output shaft.

So that the vehicle can also be moved with a gear ratio greater than 1: 1 or with the engine stopped, e.g. for towing or starting by pushing, this freewheel is equipped with a locking element that can be released from the outside, e.g. 48, provided. A separate parking lock is therefore not necessary.

Claims

Expectations

1. Drive system for systems operated with an internal combustion engine, for example motor vehicles, with control and regulating elements for setting and maintaining predeterminable operating states, with a mechanical compressor of the displacer type, with a transmission with which the driving force of the motor can be distributed into two components, wherein one of the components can be transferred to the output shaft of the system and can be driven with the other component of the compressor, and on the one hand the compressor draws in and compresses air to charge the engine and on the other hand transfers power back to the transmission and the output speed can be adjusted continuously using throttle valves characterized in that the compressor (32) has an overpressure chamber (33) on the engine side and a vacuum chamber (31) on the intake side and the vacuum chamber (31) has a throttle valve (D 1) that the overpressure chamber (33) and the vacuum chamber (31 ) parallel to their Förderstr corner via at least one return flow channel (34) with a throttle valve (D 3) are connected to each other that with the help of a further throttle valve (D 1) part of the compressor drive torque is used to generate negative pressure in the negative pressure chamber (31) and a pneumatic device (3) transmits a retroactive torque to the output shaft (23), this retroactive torque being proportional to the pressure difference between the pressure in the pressure chamber (33) and in the vacuum chamber (31).

2. Drive system according to claim 1, characterized in that the average temperature between the pressure chamber (33) and the vacuum chamber (31) is approximately constant.

3. Drive system according to claim 1 and 2, characterized in that the average temperature between the pressure chamber (33) and the vacuum chamber (31) by means of throttle valves (D 1, D 2, D 3) is kept approximately constant.

4. Drive system according to claims 1 to 3, characterized in that a temperature compensation predominantly within the system by a flow of conveying air from the vacuum chamber (31) to the pressure chamber (33) and a return flow from the pressure chamber (33) to the vacuum chamber (31) via a Reverse flow channel (34) takes place.

5. Drive system according to one or more of claims 1 to 4, characterized in that the vacuum chamber (31) is provided with connection points for servo units operated with vacuum.

6. Drive system according to one or more of claims 1 to 5, characterized in that the throttle valves (D 1, D 2) are provided with nozzles which are in the direction of

Monotonously taper the air flow so that a maximum current density occurs at the respective nozzle end.

7. Drive system according to one or more of claims 1 to 6, characterized in that at least one return flow channel (34) is provided which can be used in both directions of the air flow in the compressor (32) for forward and reverse running.

8. Drive system according to one or more of claims 1 to 7, characterized in that one or more reduction stages can be switched on depending on the engine power by means of coaxial planetary gear sets.

9. Drive system according to claims 1 and 8, characterized in that the reduction stages overlap in phases in their effect, can be activated or deactivated one after the other.

10. Drive system according to claim 9, characterized in that the change of the individual reduction phases of the speed ratio between the crankshaft of the internal combustion engine and the compressor (32) takes place without external switching elements.

11. Drive system according to one or more of claims 1 to 10, characterized in that an additional freewheel is provided which blocks the advance of the output shaft relative to the drive shaft and this freewheel is assigned to one of the planetary gear sets used.

12. Drive system according to claim 11, characterized in that the freewheel can be switched on via a locking element (48) and this lock can be released by external intervention with the engine stopped.