WO2013112048A1

WO2013112048A1 - Starting device for starting a combustion engine

Info

Publication number: WO2013112048A1
Application number: PCT/NL2013/050036
Authority: WO
Inventors: VAN Roëll Marie DRUTEN; Alexander Franciscus Anita Serrarens; Bas Gerard Vroemen
Original assignee: Dti Group B.V.
Priority date: 2012-01-23
Filing date: 2013-01-23
Publication date: 2013-08-01

Abstract

A starting device 1 for starting a combustion engine 5 has an output 3, which can be coupled to a crankshaft 7 of the combustion engine, an auxiliary drive source, which is connected to the output, and - a clutch 11, which comprises two clutch sections 13a and 13b one of which is connected to the auxiliary drive source and the other to the output. The clutch 11 further includes a spring 17 which couples the two clutch sections 13a and 13b together to become a friction clutch, as well as an actuator 19, which can move the two clutch sections apart and can pre-stress the spring during this operation, while the actuator can suddenly release the pre-stressed spring and can thus suddenly close the clutch.

Description

Starting device for starting a combustion engine

DESCRIPTION:

Field of the invention The invention relates to a starting device for starting a combustion engine, comprising:

an output, which can be coupled to a crankshaft of the combustion engine, an auxiliary drive source, which is connected to the output, and

a clutch, which comprises two clutch sections one of which is connected to the auxiliary drive source and the other to the output.

State of the art

A starting device for starting a combustion engine is generally known. Starting devices of this type are also used for starting combustion engines in vehicles that have a start- stop system in which the combustion engine, in case of standstill and under certain circumstances when the accelerator is released, is temporarily turned off so as to be re-started when the vehicle is launched. The re-starting is effected by means of an auxiliary drive source (starter motor) and is to happen fast. To this end the auxiliary drive source is to be coupled fast to the combustion engine and equally fast a high torque is to be realized on the crankshaft of the combustion engine.

Summary of the invention

It is an object of the invention to provide a starting device of the type defined in the opening paragraph in which the auxiliary drive source can be coupled in a simple manner and fast to the combustion engine without requiring much energy for this action. For this purpose the starting device according to the invention is characterized in that

- the clutch further includes a spring, which couples the two clutch sections together as a friction clutch, as well as an actuator which can move the two clutch sections apart and can pre- stress the spring in this operation, where the actuator can suddenly release the pre-stressed spring and can thus suddenly close the clutch.

By means of this spring and actuator the clutch can be closed fast, whereas only a relatively small electric motor is needed that needs to be able to produce only little power. This causes the cost of the clutch and actuator to be reduced considerably.

Preferably, the auxiliary drive source is formed by a flywheel. The combustion engine is in that case started by the kynetic energy from the flywheel, as a result of which also the auxiliary drive source asks for little power from the electric system of the vehicle. Preferably, the starting device further includes an auxiliary electric motor, which is connected to the flywheel. In an advantageous embodiment the flywheel is formed by the rotor of the auxiliary electric motor.

In a further advantageous embodiment the clutch is arranged as a friction clutch as a result of which the two clutches can be coupled together in a simple manner. The friction clutch is preferably arranged as a dry plate friction clutch. If the clutch is open, there are minimal or no slip losses while the flywheel is rotating.

In a further advantageous embodiment the two clutch sections each comprise various clutch plates or clutch discs, which can be pushed together.

An embodiment of the starting device according to the invention is characterized in that the starting device comprises a further clutch and/or freewheel bearing and/or centrifugal decoupling, which is present between the clutch and the output. As a result of this the clutch need not directly be opened after the starting of the combustion engine and it is avoided that the flywheel is revved up too much during driving.

Yet another advantageous embodiment of the starting device according to the invention is characterized in that the actuator comprises an electric motor as well as a transmission connected to the electric motor and a cam and pawl cooperating with each other, of which one of the parts is connected to the transmission and the other part to one of the clutch sections, where the pawl may suddenly slip off the cam. The transmission preferably has a high gear ratio (retarding from the electric motor onwards) so that the electric motor needs to produce only low torque resulting in a light and thus cost effective embodiment of the electric motor. The gear ratio preferably exceeds 5. An advantageous embodiment of a suitable transmission with a large gear ratio is a ring gear with internal splines in which a small pinion is traveling. A further advantageous embodiment of the starting device according to the invention is characterized in that the transmission is self -braking so that, in case of a breakdown of the auxiliary electric motor, the clutch is not closed unintentionally.

An embodiment of the starting device according to the invention is characterized in that the cam is wedge-shaped and the pawl forms a cam follower cooperating with the cam, for example a screw-line-shaped cam around a cylinder, where a rotation is converted into an axial displacement during which operation a spring is pre-stressed. If the wedge-shaped cam rotates past a specific angle, the cam follower slips off the cam and the spring is suddenly released, so that the clutch is rapidly closed.

The transmission is preferably a worm-worm gear transmission of which the worm is connected to the electric motor and the worm gear is provided with the pawl.

The clutch s preferably concentrically present within the flywheel thus forming a compact module. Furthermore, the clutch and the flywheel are preferably located within a single housing and preferably the clutch and the flywheel are directly connected to each other.

The output is preferably formed by a gear that cooperates with a starter ring gear of a combustion engine or by a pulley that cooperates with the timing belt of the combustion engine. This timing belt is mostly a multi V-belt or toothed belt.

In a further advantageous embodiment the starting device comprises a starter motor that is connected to the output. This starter motor may be helpful in case of cold starting.

A still further embodiment of the starting device according to the invention is characterized in that the starting device comprises one or more reduction gearings which are each present between two of the parts of the starting device. This reduction gearing may be a gear reduction, a planetary gear set having a single rotational member fixedly connected to the firm world, a belt or chain transmission etc. As a result, among other things the load (torque) on the clutch may be reduced, the torque produced by the flywheel increased, and the starting device may be of compact construction. Brief description of the drawings

The invention will be described in more detail based on examples of embodiment of the starting device according to the invention shown in the drawings while reference is made to the appended drawing figures, in which: Fig. 1 shows a first embodiment of the starting device according to the invention when the clutch is being opened;

Fig. 2 shows the starting device shown in Fig. 1 shortly before the closing of the clutch;

Fig. 3 shows the starting device shown in Fig. 1 immediately after the closing of the clutch;

Fig. 4 shows a second embodiment of the starting device according to the invention comprising a transmission and a further clutch;

Fig. 5 shows a third embodiment of the starting device according to the invention comprising a further transmission requiring less build-in length; and

Fig. 6 shows a fourth embodiment of the starting device according to the invention requiring even less build-in length.

Detailed description of the drawings

Figs. 1, 2 and 3 show a first embodiment of the starting device according to the invention, shown when the clutch is being opened, shortly before the closing of the clutch and immediately after the closing of the clutch, respectively. The starting device 1 has an output 3 which is connected to a crankshaft 7 of a combustion engine 5. The starting device comprises an auxiliary drive source, which is arranged as a flywheel 9 that is connected to the output via a clutch 11.

The clutch is arranged as a friction clutch and comprises two clutch sections 13a and 13b one of which is connected to the flywheel 9 and the other is connected to the output 5 via a splined connection 15. The clutch 11 further has a spring 17 that is capable of coupling the two clutch sections together as a friction clutch, and an actuator 19. This actuator is formed by an electric motor 21 and a worm-worm gear transmission of which the worm 23 is connected to the electric motor and the worm gear 25 is provided with a pawl 27 which can catch on a protuberance/cam (flange) 29 on the clutch section 13b.

This actuator can move the two clutch sections 13a and 13b apart and, while doing this, pre-stress the spring 17 (see Fig. 1). In pre-stressed condition of the spring 17 (see Fig. 2) the pawl 27 will slip off the protuberance 29 when the worm gear 25 rotates further, as a result of which the spring 17 is suddenly released and thereby suddenly pushes the clutch sections 13a and 13b against each other and thus closes the clutch (see Fig. 3). As a result, the combustion engine 5 can be started rapidly with the energy from the flywheel 9. The starting device further includes an auxiliary electric motor 31 which is connected to the flywheel 9 to keep the flywheel at the right speed. The flywheel may then be arranged as the rotor of the auxiliary electric motor.

Fig. 4 shows a second embodiment of the starting device according to the invention. This starting device 33 further includes a further clutch which is arranged as a freewheel bearing 35, which is located between the clutch 11 and the output 3. Further the starting device includes a reduction gearing 37 which is present between the clutch and the further clutch and which is formed by a planetary gear set of which one of the rotational members is fixed to the firm world (for example the bodywork of the vehicle).

To the crankshaft 7 of the combustion engine 5 is fixed near one end 7a a motor flywheel 39 (either provided or not with a starter gear ring) and near the other end 7b is fixed to the crankshaft a pulley of the distributor transmission 41. The other pulley of the distributor transmission is connected to a generator 43. The starting device 33 is connected to the end 7b of the crankshaft.

Fig. 5 shows a third embodiment of the starting device according to the invention. This starting device 45 is provided with a further transmission (reduction gearing) which is formed by a belt transmission 47 and is present between the flywheel 9 and the auxiliary electric motor 31. This allows of a more compact construction, so that less build-in length is required.

Fig. 6 shows a fourth embodiment of the starting device according to the invention. In this starting device 49 the belt transmission 47 is located between the reduction gearing 37 and the clutch 11, so that the starting device is even more compact and requires even less build-in length.

Albeit the invention has been described in the foregoing with reference to the drawings, it should be pointed out that the invention is not by any manner or means restricted to the embodiments shown in the drawings. The invention also extends over any embodiment deviating from the embodiment shown in the drawing Figures within the spirit and scope defined by the claims. For example, the further clutch may also be arranged as a centrifugal decoupling in lieu of a freewheel bearing.

Claims

CLAIMS:

1. A starting device (1; 33; 45; 49) for starting a combustion engine (5), comprising:

an output (3), which can be coupled to a crankshaft (7) of the combustion engine, - an auxiliary drive source, which is connected to the output, and

a clutch (11), which comprises two clutch sections (13a, 13b) one of which is connected to the auxiliary drive source and the other to the output,

characterized in that

the clutch (1 1 ) further includes a spring (17), which couples the two clutch sections (13a, 13b) together as a friction clutch, as well as

an actuator (19), which can move the two clutch sections apart and can pre-stress the spring in this operation, where the actuator can suddenly release the pre-stressed spring and can thus suddenly close the clutch.

2. A starting device (1; 33; 45; 49) as claimed in claim L characterized in that the auxiliary drive source is formed by a flywheel (9).

3. A starting device (1; 33; 45; 49) as claimed in claim 2, characterized in that the starting device further includes an auxiliary electric motor (31), which is connected to the flywheel (9).

4. A starting device (1; 33; 45; 49) as claimed in any one of claims 1, 2 or 3, characterized in that the flywheel (9) is formed by the rotor of the auxiliary electric motor (31).

5. A starting device (1; 33; 45; 49) as claimed in any one of the preceding claims, characterized in that the clutch (11) is a friction clutch.

6. A starting device (1; 33; 45; 49) as claimed in claim 5, characterized in that the clutch (11) is a dry plate friction clutch.

7. A starting device (1; 33; 45; 49) as claimed in any one of the claims 5 or 6, characterized in that the two clutch sections (13a, 13b) each comprise various clutch plates or clutch discs which can be pushed together.

8. A starting device (33; 45; 49) as claimed in any one of the preceding claims, characterized in that the starting device comprises a further clutch and/of freewheel bearing (35) and/or centrifugal decoupling, which is present between the clutch (11) and the output (3).

9. A starting device (1; 33; 45; 49) as claimed in any one of the preceding claims, characterized in that the actuator (19) comprises an electric motor (21) as well as a transmission connected to the electric motor and a cam (29) and pawl (27) cooperating with each other, of which one of the parts is connected to the transmission and the other part to one of the clutch sections (13b), where the pawl may suddenly slip off the cam.

10. A starting device (1; 33; 45; 49) as claimed in claim 9, characterized in that the transmission is a self-braking transmission.

11. A starting device as claimed in claim 10, characterized in that the cam is wedge-shaped and the pawl forms a cam follower cooperating with the cam.

12. A starting device (1; 33; 45; 49) as claimed in claim 10, characterized in that the transmission forms a worm-worm gear transmission of which the worm (23) is connected to the electric motor (21) and the worm gear (25) is provided with the pawl (27).

13. A starting device (1; 33; 45; 49) as claimed in claim 2 or any one of the preceding claims 3 to 12 and claim 2, characterized in that the clutch (11) is concentrically present within the flywheel (9).

14. A starting device (1; 33; 45; 49) as claimed in claim 2 or any one of the preceding claims 3 to 12 and claim 2, characterized in that the clutch (11) and the flywheel (9) are located within a single housing.

15. A starting device (1; 33; 45; 49) as claimed in claim 2 or any one of the preceding claims 3 to 12 and claim 2, characterized in that the clutch (11) and the flywheel (9) are directly connected to each other.

16. A starting device as claimed in any one of the preceding claims, characterized in that the output is formed by a gear that cooperates with a starter ring gear of a combustion engine.

17. A starting device as claimed in any one of the preceding claims 1 to 15, characterized in that the output is formed by a pulley that cooperates with the timing belt of the combustion engine.

18. A starting device as claimed in any one of the preceding claims, characterized in that the starting device comprises a starter motor which is connected to the output.

19. A starting device (33; 45; 49) as claimed in any one of the preceding claims, characterized in that the starting device comprises one or more reduction gearings (37, 47) which are each present between two of the parts of the starting device.