Patent Application
20160115934
Exemplary embodiments pertain to the art of motor vehicles and, more particularly, to an internal combustion engine having a starter system.
Internal combustion engines generally include a starter motor. The starter motor is electrically energized to initiate operation of the internal combustion engine. A typical starter includes a starter motor that generates torque that is passed to a pinion gear and a solenoid. The solenoid shifts the pinion gear into engagement with a ring gear on the internal combustion engine. Once engaged, the starter motor rotates the pinion to spin the ring gear and initiate operation of the internal combustion engine.
In a standard starter motor a generally stationary pinion is shifted into engagement with a stationary ring gear. The pinion is shifted such that pinion teeth enter a gap between ring gear teeth for engagement. While shifting, the pinion gear may experience a small rotation. Once engaged, the pinion gear rotates the ring gear. To ease this engagement, it is common to chamfer the pinion teeth on the trailing edge. In some cases, the leading edge of the ring gear teeth is also chamfered.
Also disclosed is an internal combustion engine including a ring gear having a plurality of ring gear teeth. Each of the plurality of ring gear teeth includes a leading edge surface and a trailing edge surface. A starter motor is mounted to the internal combustion engine. The starter motor includes a pinion gear having a plurality of pinion gear teeth configured and disposed to selectively engage with the plurality of ring gear teeth. Each of the plurality of pinion gear teeth includes a leading edge surface portion and a trailing edge surface portion. The pinion gear is configured and disposed to engage with the ring gear while the ring gear is coasting. At least one of the trailing edge surface of each of the plurality of ring gear teeth and the leading edge surface portion of each of the plurality of pinion gear teeth includes a chamfer.
Also disclosed is a method of engaging a pinion gear with a rotating ring gear to start an internal combustion engine including shifting the pinion gear having a plurality of pinion gear teeth towards the ring gear having a plurality of ring gear teeth, and guiding a leading edge surface portion of one of the plurality of pinion gear teeth along a trailing edge surface of one of the plurality of ring gear teeth. At least one of the leading edge surface portion and trailing edge surface includes a chamfer. The method also includes contacting the trailing edge surface portion of the one of the plurality of pinion gear teeth with a leading edge surface of another one of the plurality of ring gear teeth along the chamfer, and rotating the pinion gear to initiate operation of the internal combustion engine.
The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
Recently, manufacturers have started to develop start-stop vehicles to enhance fuel economy. In a start-stop vehicle, an engine is automatically shut off when the vehicle comes to a stop, near stop, or is coasting. The engine is then automatically restarted by the starter motor when an auto restart signal is received. For a short period after the engine is shut off, the engine will continue to coast in a forward direction. This engine coasting may cause a change-of-mind (COM) condition in which an operator changes his mind rather quickly and causes an auto restart signal to be generated while the engine is still coasting. In this COM condition, a starter motor may be signaled to engage the pinion while the engine is coasting in the forward direction. Consequently, the pinion, which may not be rotating, is shifted axially forward to engage a rotating ring gear. Relative motion of the ring gear and the pinion when the ring gear rotates in the forward direction (COM start) is the same as if the pinion was rotating in the reverse direction. In such cases, the pinion gear, with the trailing edge chamfer, cannot engage with the ring gear until a pinion gear tooth aligns with a gap between ring gear teeth. Therefore the trailing edge chamfer on the pinion does not cause a smoother engagement with the ring gear and, milling, or wear on the pinion gear teeth may occur. As will be detailed below, the present invention alleviates milling or wear on the pinion gear during a COM start.
An internal combustion engine, in accordance with an exemplary embodiment, is indicated generally at 2, in
Electrical energy passing through terminals 53 energizes one or more of coils 40 and 42. The one or more of coils 40 and 42 create a magnetic flux that draws in actuator 44 causing lever 46 to shift pinion gear 34 along output shaft 30 and into engagement with ring gear 6, as will be detailed more fully below. In accordance with an aspect of the exemplary embodiment, actuator 44 is also coupled to contacts 55. As actuator 44 is drawn in, contacts 55 electrically connect with terminals 53 to deliver current to a motor portion (not shown) of starter motor 4 causing a driving torque to be delivered to pinion gear 34. Of course, it should be understood that pinion gear 34 could be caused to rotate prior to engagement with ring gear 6.
In accordance with another aspect of the exemplary embodiment, starter motor 4 is configured to guide pinion gear 34 into engagement with a rotating ring gear 6. Specifically, in many hybrid vehicles, an actuation of a brake may cause the internal combustion to cease operation. While operation may be ceased, ring gear 6 may continue to rotate. In the event a driver decides not to stop, and depresses an accelerator or simply releases the brake, a change of mind (COM) signal may be triggered. The COM signal activates starter motor 4 to re-initiate operation of the internal combustion engine. That is, in the event that the internal combustion engine is not rotating at a speed that would allow for re-ignition, starter motor 4 is activated. As will be detailed more fully below, starter motor 4 is configured to shift pinion gear 34 into engagement with ring gear 6 even if ring gear 6 is still rotating. Starter motor 4 may be activated to re-initiate operation when the ring gear 6 is rotating faster than 200 RPM.
As shown in
In accordance with an aspect of the exemplary embodiment, chamfer 87 extends at least 5% along an axial length (not separately labeled) of pinion gear teeth 36. In accordance with another aspect of the exemplary embodiment, chamfer 87 extends between about 5% and about 20% along the axial length of pinion gear teeth 36. In accordance with still another aspect of the exemplary embodiment, chamfer 87 extends about 13% along the axial length of pinion gear teeth 36. In the exemplary embodiment shown, chamfer 87 includes an axial dimension 92 of about 2 mm.
In accordance with another aspect of the exemplary embodiment, chamfer 89 extends at least 5% along an axial length (not separately labeled) of ring gear teeth 8. In accordance with another aspect of the exemplary embodiment, chamfer 89 extends between about 5% and about 20% along the axial length of ring gear teeth 8. In accordance with still another aspect of the exemplary embodiment, chamfer 89 extends about 18% along the axial length of ring gear teeth 8. In the exemplary embodiment shown, chamfer 89 includes an axial dimension 94 of about 2 mm. In further accordance with an aspect of the exemplary embodiment, chamfer 87 includes an angle 97 of between about 30° and about 70°. In accordance with another aspect, angle 97 is about 45°. Similarly, chamfer 89 includes an angle 99 of about 30° and about 70°. In accordance with another aspect, angle 99 is about 45°. With this arrangement, chamfer 87 and or chamfer 89 facilitate inter-engagement of one or more of the plurality of pinion gear teeth 36 and the plurality of ring gear teeth 8. Specifically, chamfer 87 and/or chamfer 89 facilitate one of the plurality of pinion gear teeth 36 passing into gap 75 while ring gear 6 is rotating, as shown in
As shown in
At this point it should be understood that the chamfer on a trailing edge surface of the ring gear teeth and/or the chamfer on a leading edge surface portion of the pinion gear teeth facilities engagement of a stationary, e.g., non-rotating pinion gear with a ring gear that may be rotating at 200 RPM or above. It should also be understood that the axial dimension of the pinion gear teeth may vary. For example, if a chamfer is provided on one or the other of the ring gear teeth and the pinion gear teeth, the axial dimension of the pinion gear teeth may be 15 mm. If, on the other hand, both the trailing edge surface and the leading edge surface portion include a chamfer, the axial dimension of the pinion gear teeth may be 17 mm. In this manner, the ring gear teeth and pinion gear teeth include robust mating surfaces.
While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims.
