DESCRIPTION

Field of the invention.

The invention relates to a start system for a combustion engine, comprising: a first auxiliary drive source, which is constituted by an electromotor, - a second auxiliary drive source, which is constituted by a flywheel, and a clutch, which is capable of coupling one of the auxiliary drive sources to a crankshaft of the combustion engine when there is cooperation between the system and a combustion engine.

State of the art

A system of this type is known from EP-A-I 486 666. In this system the flywheel can be coupled by the clutch to the crankshaft and the electromotor forms part of a start module which is directly coupled to the crankshaft of the combustion engine. The clutch is configured here as a sliding clutch which can slide a flywheel-coupled gear along a shaft, so that this gear can be caused to engage a further gear mounted on the crankshaft. The purpose of the flywheel and the clutch in the known system is to support the start module.

Summary of the invention.

It is an object of the invention to provide a system of the type defined in the opening paragraph which takes up hardly any additional space or no additional space at all compared to a conventional start device, where an electromotor, by means of a slidable gear, can be brought into contact with a crown gear present on an engine flywheel. For this purpose the system according to the invention is characterised in that the system further includes a further clutch which can clutch-connect the two auxiliary drive sources together. As a result, the flywheel can be revved up by means of the electromotor prior to the combustion engine being started, ao while there is no coupling yet to the crankshaft. When, subsequently, the combustion engine is started, the pre-rewed flywheel is coupled to the crankshaft with the flywheel delivering additional torque. In consequence, with unmodified specifications of the electromotor the combustion engine can be taken to higher revolutions per minute (RPM) in a faster way before a start is made with the injection and combustion. As a result, the (re)start of the combustion engine is faster and more comfortable and there are fewer harmful emissions during the starting operation. Furthermore, this may improve driving away and when the combustion engine is turned off this combustion engine may be assisted by one or both auxiliary drive sources to render the turning off more comfortable.

The further clutch may be executed as a friction clutch. However, in an advantageous embodiment of the system according to the invention this further clutch is arranged as a freewheel bearing clutch. As a result, the flywheel need not take along the rotor of the electromotor if the combustion engine is started only by the use of the flywheel. In a further advantageous embodiment of the system according to the invention this further clutch is arranged as a magnetic clutch or electromagnetic clutch.

An embodiment of the system according to the invention is characterised in that the clutch is a friction clutch or claw clutch which is positioned between the auxiliary drive source to be coupled to the crankshaft and a gear that forms part of the system and is coupled to the crankshaft of the combustion engine when there is cooperation between the system cooperates and a combustion engine. When the system is applied to a vehicle, the gear can engage a further gear positioned on the crankshaft or may be coupled to a further gear on the crankshaft by means of a transmisison member, for example a timing belt.

A further embodiment of the system according to the invention is characterised in that in parallel with the clutch a planetary gear set having three rotational members is present, of which a first rotational member is connected to a first clutch half of the clutch, a second rotational member is connected to the second clutch half of the clutch and the third rotational member is connected to a brake. As a result, the torque delivered by the electromotor and/or the flywheel can be transmitted to the crankshaft at an enhanced level.

Another embodiment of the system according to the invention is characterised in that the clutch is a sliding clutch which can slide a gear along a shaft, which gear forms part of the system and is coupled to the auxiliary drive source to be coupled to the crankshaft, so that this gear is caused to engage a further gear positioned on the crankshaft of the combustion engine when there is cooperation between the system and a combustion engine.

Preferably the gear, the clutch, the further clutch, the flywheel and the electromotor are positioned in one housing concentrically to one another. Furthermore, preferably one of the auxiliary drive sources is positioned concentrically around the other auxiliary drive source or one of the auxiliary drive sources is positioned concentrically around a shaft which is connected to the other auxiliary drive source. Furthermore, preferably a reduction is present between the two auxiliary drive sources and/or between an auxiliary drive source and the clutch. The reduction is preferably constituted by a planetary gear set having at least three rotational members. Preferably, a lock-up clutch is then positioned between two out of three rotational members to provide a direct coupling between these two rotational members, so that one-to-one transmission is achieved.

The clutch and/or the further clutch may then be operable in an electromechanic, hydraulic, pneumatic, magnetic or electromagnetic way. In the case where the clutch and/or the further clutch is operable in a hydraulic way, the hydraulic pressure is preferably obtained from an oil pump of a transmission or power steering the vehicle is equipped with.

In the case where the clutch and the further clutch is operable in an electromechanic way, there preferably exists a mechanical connection between the two clutches.

The invention also relates to a vehicle comprising a combustion engine which comprises a crankshaft, as well as a system according to the invention.

An embodiment of the vehicle according to the invention is characterised in that there is a mechanical transmission between the clutch and the crankshaft.

This transmission is preferably constituted by a gear which is coupled to the auxiliary drive source to be coupled to the crankshaft, and a further gear positioned on the crankshaft.

The invention also relates to a method for turning off a combustion engine of a vehicle according to the invention, where the clutch is positioned between the electromotor and the crankshaft. With respect to this method the invention is characterised in that the electromotor initially synchronises the clutch after which the clutch is closed and subsequently the further clutch is energized, subsequent to which the combustion engine is turned off. In this way the combustion engine can be turned off in a controlled way. The electromotor can optionally act as a generator and assist in turning off the combustion engine in a controlled way. Another method for turning off a combustion engine of a vehicle according to the invention, where the clutch is positioned between the electromotor and the crankshaft, is characterised in that prior to the combustion engine being turned off, the flywheel is revved up by the combustion engine and/or the electromotor. The invention further relates to a method for restarting a combustion engine of a vehicle according to the invention, where the clutch is positioned between the electromotor and the crankshaft. With respect to this method the invention is characterised in that immediately after the combustion engine has been turned off, the flywheel is revved up by the electromotor with a slip clutch or closed further clutch, after which the further clutch is opened and the electromotor is turned off and then the clutch is closed subsequent to which the combustion engine is started.

Furthermore, the invention relates to a method for starting a combustion engine of a vehicle according to the invention, where the clutch is positioned between the electromotor and the crankshaft. With respect to this method the invention is characterised in that the moment the driver indicates that he wishes to start driving, which may be the moment he lets go of the brake pedal or clutch pedal or when he depresses the clutch pedal or accelerator or when he moves the gearchange lever, the further clutch is closed or the further clutch is closed and the electromotor is turned on, after which the combustion engine is started and subsequent to this the clutch and/or further clutch is opened. The invention also relates to a method for turning off a combustion engine of a vehicle according to the invention, where the clutch is positioned between the flywheel and the crankshaft. With respect to this method the invention is characterised in that the clutch is closed after which the combustion engine is turned off. In this way the combustion engine can be turned off in a controlled way. The electromotor can optionally act as a generator, and with a closed further clutch, assist in turning off the combustion engine in a controlled way.

Another method for turning off a combustion engine of a vehicle according to the invention where the clutch is positioned between the flywheel and the crankshaft is characterised in that prior to the combustion engine being turned off the flywheel is revved up by the combustion engine and/or the electromotor. Further the invention relates to a method for restarting a combustion engine of a vehicle according to the invention, where the clutch is positioned between the flywheel and the crankshaft. With respect to this method the invention is characterised in that immediately after the combustion engine has been turned off the flywheel is revved up by the electromotor with a slip-clutch or closed further clutch, after which the further clutch is opened and the electromotor is turned off while the clutch remains open and subsequent to this the combustion engine is started.

The invention further relates to a method for starting a combustion engine of a vehicle according to the invention, where the clutch is positioned between the flywheel and the crankshaft. With respect to this method the invention is characterised in that the moment the driver indicates that he wishes to start driving, which may be the moment he lets go of the brake pedal or clutch pedal or when he depresses the clutch pedal or accelerator or when he moves the gearchange lever, the clutch is closed or the clutch is closed and the electromotor is turned on, while a further clutch is closed, after which the combustion engine is started and subsequent to this the clutch is opened.

Brief description of the drawings.

The following description relating to the appended drawings, the whole given by way of non-limiting example of the start system for a combustion engine according to the invention, will provide better understanding of how the invention can be realised, in which: Fig. 1 shows the lay-out of a conventional start system; Fig. 2 shows a basic circuit diagram of a first embodiment of the system according to the invention; Fig. 3 shows a lay-out of a first variant of the first embodiment;

Fig. 4 shows a lay-out of a second variant of the first embodiment; Fig. 5 shows a basic circuit diagram of a second variant of the system according to the invention;

Fig.6 shows a lay-out of a first variant of the second embodiment; Fig. 7 shows a lay-out of a second variant of the second embodiment;

Fig. 8 shows a lay-out of a third variant of the second embodiment; Figs. 9, 10, 11 and 12 show alternative constructions of systems of the systems shown in Figs. 3, 4, 6 and 7; and

Fig. 13 shows an embodiment of the system according to the invention in concrete form.

Detailed description of the drawings Fig. 1 shows the lay-out of a conventional start system 1 for starting a combustion engine 3. In this conventional start system 1 an electromotor 5 can be brought into contact with a crown gear 11 by means of a gear 9 which can axially slide over a shaft 7 and is fixed to the sahft in the direction of rotation, which crown gear 11 belongs to an engine flywheel 15 positioned on a crankshaft 13 of the conbustion engine 3. A planetary gear set 17 having three rotational members is positioned between the electromotor 5 and the gear 9. From this planetary gear set a first rotational member is connected to the electromotor 5, a second rotational member is coupled to the gear 9 and the third rotational member is connected to mass 19, for example the housing of the electromotor. The gear 9 is connected via a freewheel bearing 21 to a sliding clutch. This sliding clutch is constituted by a bus 23 which is connected to the shaft 7 which is a splined shaft, and an actuator 25 which can slide the bus 23 over the shaft 7 by means of a lever 27. The planetary gear set 17 constitutes an additional reduction in addition to the reduction constituted by the gear and the crown gear as a result of which the required torque for starting the combustion engine 3 can be delivered by the electromotor 5.

Fig. 2 shows a basic circuit diagram of a first embodiment of the system according to the invention for starting a combustion engine. In addition to the electromotor 33 which can be coupled via a clutch 35 to the crankshaft 37 of the combustion engine, this system 31 comprises another flywheel 41 which can be coupled to the electromotor 33 via a further clutch 43.

Fig. 3 shows the lay-out of a first variant of this embodiment. In this system 45 the clutch 35 is arranged as a sliding clutch which can cause a gear 47 which is slidable along a shaft to engage a crown gear of an engine flywheel 49 positioned on the crankshaft 37. The further clutch 43 in this system is arranged as a friction clutch. Starting the combustion engine 39 in case of a cold start or a restart after the combustion engine has been turned off at a low vehicle speed (coasting) or brief standstill (for example at a traffic light) is performed in the following way. While the gear 47 is disengaged from the crown gear of the engine flywheel 49 and the clutch 43 is closed, the electromotor 33 is turned on. The electromotor then brings the flywheel 41 to the desired (maximum) RPM. It is alternatively possible to first rev up the electromotor 33 with an open clutch 43 and close this clutch afterwards. After the flywheel 41 has been revved up, the electromotor 33 can be turned off and the clutch 43 opened and the gear 47 can be made to engage the crown gear of the engine flywheel 49. If the combustion engine 39 is to be started, the clutch 43 is closed as a result of which the flywheel 41 delivers the required torque for the combustion engine to start. If so desired, the electromotor 33 can also be activated to support the start. After the combustion engine 39 has been started the gear 47 can again be disengaged from the engine flywheel 49. Fig. 4 shows the lay-out of a second variant of the first embodiment of the system according to the invention. All component parts that are equal to those of the first variant shown in Fig. 3 have like reference numerals. In this system 51 the flywheel 41 is concentrically pivotable around the shaft 53 to which the electromotor 33 is connected. The clutch 43 is arranged as a friction clutch here too and can connect the flywheel 41 to the shaft 35.

Fig. 5 shows a basic circuit diagram of a second embodiment of the system according to the invention for starting a combustion engine. All component parts that are equal to those of the first embodiment shown in Fig. 2 have like reference numerals. In this system 55 the flywheel 41 can be coupled to the crankshaft 37 of the combustion engine 39 via the clutch 35, and the electromotor 33 can be coupled to the flywheel 41 via the further clutch 43.

Fig. 6 shows the lay-out of a first variant of this embodiment. In this system 57 the gear 47 continuously engages the crown gear of the engine flywheel 49 and the gear 47 can be coupled by means of the clutch 35 arranged as a fiiction clutch to the flywheel 41 which is fixedly mounted on the shaft 59. The flywheel 41 is coupled to the electromotor 33 via the further clutch 43 arranged as a freewheel bearing clutch.

When the combustion engine 39 is started by means of the flywheel 41, the electromotor 33 is disengaged from the flywheel by the freewheel bearing clutch, so that this combustion engine need not take along the rotor of the electromotor. If so desired, when the combustion engine is started the electromotor can be switched on to deliver additional torque, for example in the case of a cold start.

Fig. 7 shows the lay-out of a second variant of the second embodiment of the system according to the invention. All component parts that are equal to those of the first variant shown in Fig. 6 have like reference numerals. In this system 61 the electromotor 33 is concentrically pivotable around the shaft 63 to which the flywheel 41 is connected and the flywheel 41 can be coupled to the gear 47 via the clutch 35. The clutch 43 is again arranged as a friction clutch and can couple the electromotor 33 to the flywheel 41.

Fig. 8 shows the lay-out of a third variant of the second embodiment of the system according to the invention. All component parts that are equal to those of the second variant shown in Fig. 7 have like reference numerals. In this system 63 there is a possibility to insert an additional reduction between the gear 41 and the gear 47 as a result of which it is possible for the torque delivered by the gear 41 and/or the electromotor 33 ro be transmitted to the gear 47 in enhanced form. The additional reduction is formed by a planetary gear set 65 which is in parallel with the clutch 35. The planetary gear set 65 has three rotational members a first rotational member of which is connected to a first clutch half 35a, a second rotational member of which is connected to the second clutch half 35b and the third rotational member of which is connected to a brake 69. Figs. 9, 10, 11 and 12 show alternative constructions of systems 45', 51% 57' and 61' of the systems shown in Figs. 3, 4, 6 and 7 respectively, with the flywheel and the clutch and the optional further clutch being positioned in a housing 71 which is in essence airtight and in which there is a partial vacuum so as to reduce the air resistance set up by the flywheel. Fig. 13 shows an embodiment of the system according to the invention in concrete form. The further clutch is here arranged as a conical clutch. The flywheel 73 has a conical surface 75 which constitutes part of the further clutch and the other part of the further clutch is constituted by a clutch member 77 which has a further conical surface 79. By adding oil through the oil pipe 81 the piston 83 will move to the right so that the two conical surfaces are pressed together. The clutch member is connected via a spline connection 85 to an intermediate member 87 which in its turn is connected via a further spline connection 89 to the shaft 91 of the electromotor 93.

Although the invention has been described in the foregoing based on the drawings, it should be observed that the invention is not by any manner or means restricted to the embodiment shown in the drawings. The invention also extends to all embodiments deviating from the embodiment shown in the drawings within the spirit and scope defined by the claims.