JPH04185921A - Roller clutch for starter - Google Patents

Abstract

PURPOSE:To secure stable clutch function to increase durability of a clutch by keeping balance of the rigidities of a clutch outer unit and clutch inner unit so that load distribution applied to rollers in axial direction becomes uniform when these units are engaged with wedges. CONSTITUTION:An axial load applied to rollers 5 during transmission of torque is uniformed by keeping balance of the rigidities of an clutch outer unit 2a and clutch inner unit 3 in accordance with analysis by finite element method so that the seconds of arc of these units become equal when a unit load is applied onto a clutch. By this, the rollers 5 are fitted closely and engaged with an wedge chamber, which is formed with the clutch outer unit 2a and clutch inner unit 3, at a uniform surface pressure to transmit torque uniformly. When an engine is combusted completely and a pinion 4 and the clutch inner unit 3 are rotated together, these units are disengaged and, even when the engine operation is brought to overrunning condition, disengagement of the clutch can be made stably without causing seizure since surface pressure during engagement of the rollers is set uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a roller clutch for a starter, and particularly to improving torque transmission characteristics and overrun performance.

[Conventional technology]

Conventionally, a roller clutch installed in a starter for starting an internal combustion engine such as an automobile has a structure as described in Japanese Utility Model Application No. 59-195231. In FIG. 3 showing the structure, the clutch sleeve 2 includes a spline tube 2b that is helically spline engaged with the pinion shaft 1, which is a rotating output shaft, and a clutch outer 2a that has a wedge-shaped profile on its inner peripheral surface. Since it is integrally molded, it has an open structure on the pinion side.

Therefore, when the roller clutch is transmitting torque, that is, the clutch outer 2a and the clutch inner 3 are connected to the roller 5.
In the wedge-engaged state, the rollers 5 roll in the narrow direction of the wedge within the profile of the clutch outer 2a, causing relative torsion between the clutch outer 2a and the clutch inner 3.

At that time, a load proportional to the transmitted torque is applied to the clutch outer 2.
a and the roller contact portion of the clutch inner 3, that is, distributed in the axial direction. According to FIG. 4, since the rigidity of the roller 5 is greater than that of the clutch outer 2a and the clutch inner 3, if the deformation of the roller 5 is ignored, the clutch outer 2a and the clutch inner 3 are shown in cross-sectional view. The clutch outer 2a is displaced like a cantilever wedge, and when viewed as a whole, the clutch outer 2a expands outward in a lattice shape, and the clutch inner 3 has a concave shape inward. Therefore, the roller 5 is tilted in the axial direction, and the load distribution in the axial direction of the roller 5 is not uniform but is determined by the difference in rigidity between the clutch outer 2a and the clutch inner 3. Put it away.

[Problem to be solved by the invention]

In the above conventional technology, the design of the clutch outer 2a and the clutch inner 3 is such that the stress value under the actual working load is within the allowable value of the material, or rather, it is determined based on the dimensions with the surrounding parts. For these reasons, not much consideration was given to the rigidity balance between the two. As a result, the roller 5 receives a partial heavy load due to the unbalanced rigidity between the clutch outer 2a and the clutch inner 3 during normal rotation torque transmission, and falls down, resulting in uneven contact. In such a state, good torque transmission is not carried out, and this may lead to impressions on the clutch inner 3 and uneven wear of the rollers. Furthermore, even when transitioning from normal rotation engagement to overrun state, since the roller 5 bites into the wedge unevenly, it is not possible to disconnect with stable torque, making it possible to obtain smooth overrun performance. The object of the present invention is to take clutches into consideration and obtain good torque transmission characteristics and overrun performance. Conventionally, in order to improve the clutch function, eccentricity and inclination of the clutch outer 2a and clutch inner 3 were often restricted, but the present invention aims to make the load distribution caused by the inclination of the roller 5 uniform. The aim is to ensure stable clutch function and improve durability.

[Means to solve the problem]

In order to achieve the above object, an analysis using the finite element method was performed to determine the stiffness of the clutch outer 2a and the clutch inner 3, and to balance them.

As mentioned above, during torque transmission, since the clutch outer 2a and the clutch inner 3 have different rigidities, the rigidity is unevenly distributed in the axial direction as shown in the figure, resulting in a state of partial contact between the rollers. In other words, the case where the clutch inner 3 is rigid and the clutch outer 2a is flexible corresponds to the case shown in FIG. 4, and since the displacement of the soft clutch outer 2a is large, most of the load is placed near the base, which is the rigid part. As a result, the contact pressure increases, and the open side, which is the soft part, is displaced greatly, resulting in a state where the contact pressure does not increase much.

Therefore, by controlling the rigidity of the clutch outer 2a and the clutch inner 3 so as to make these distributed loads uniform in the axial direction, it is possible to realize a roller clutch in which both of them are well-balanced. Specifically, the clutch outer 2a
The thickness of each part of the clutch outer 2a and the clutch inner 3 is reinforced or thinned so that the slopes of the respective displacements when a unit-wise distributed load is applied to the clutch inner 3 and the clutch inner 3 are reinforced or thinned. This results in an optimal design for the clutch as a whole.

[Effect]

Based on analysis using the finite element method, by balancing the rigidity of the clutch outer 2a and the clutch inner 3 so that the displacement angles of the clutch outer 2a and the clutch inner 3 are equal when a unit load is applied, the axial load that the roller 5 receives during torque transmission can be reduced. It becomes possible to make it -like.

As a result, the clutch outer 2a and the clutch inner 3
The roller 5 bites into and engages with the wedge chamber formed by the --like surface pressure, thereby transmitting torque evenly. Then, when the engine is fully exposed and the pinion 4 and clutch inner 3 are rotated, their engagement is released and even when transitioning to an overrun state, the surface pressure when the rollers are engaged is uniform. This allows the clutch to be disengaged stably without causing seizure or the like. Therefore, the present invention provides a smooth latch function.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a longitudinal sectional view of a starter roller clutch that best represents the features of the present invention.

In FIG. 1, 1 is a pinion shaft rotationally driven by a starter motor (not shown), 1a is a helical spline formed on the pinion shaft 1, 2 is a clutch sleeve, and 2a is a wedge-shaped profile on its inner peripheral surface. 2b is a spline tube integrally molded with the clutch outer 2a, 2c is a helical spline formed on the inner peripheral surface of the spline tube 2b, 3 is a clutch inner disposed inside the clutch outer 2a, 4 is a A pinion that is integrally molded with the clutch inner 3 and transmits the power of the pinion shaft 1 to an engine ring gear (not shown); 5 is a roller disposed in a wedge space formed by the clutch outer 2a and the clutch inner 3; 6;
is a washer fixed to the open side of the clutch outer 2a by a clutch cover 8 together with a seal member 7 in order to restrict the movement of the roller 5 in the axial direction and to close off the wedge space.

Next, the operation of the above configuration will be explained. A pinion shaft 1 is rotationally driven by a starter motor (not shown), and a helical spline la is rotated.

2c, it is transmitted to the clutch outer 2a integrated with the spline tube 2b. clutch outer 2a
When the roller 5 rotates, the roller 5 disposed in the wedge space rolls in the narrow direction of the wedge, engages the clutch inner 3, and transmits power to the pinion 4 integrated with the clutch inner 3, which drives the engine ring gear (not shown). drive and start the engine. During torque transmission, the roller clutch causes relative torsion in the clutch outer 2a and clutch inner 3 with respect to the transmission direction. It has the function of buffering the impact torque caused by pinion engagement during startup, and slipping in the forward rotation direction against excessive impact torque to protect mechanical parts such as the reducer (not shown) from damage. There is.

After the engine is started, the pinion 4 is rotated by a ring gear (not shown). At this time, the roller 5 is disengaged from the clutch outer 2a and the clutch inner 3, and the structure is such that the overrun torque from the engine is separated, thereby preventing burnout of the starter motor (not shown).

In the conventional roller clutch structure, as shown in FIG. 3, the stiffness of the clutch outer 2a and the clutch inner 3 is such that the displacement angles with respect to a unit distributed load are not equal and are not balanced. According to the example analyzed using the finite element method in FIG. 5, this corresponds to the solid lines marked with white circles and black circles. The white circles indicate the combination of the rigid clutch outer 2a and the soft clutch inner 3, and the black circles indicate the opposite combination. For this reason, as shown in FIG. 4, the load distribution in the axial direction of the roller is not uniform, and there are areas where the surface pressure is locally high, resulting in a state of uneven contact due to the fall of the roller 5.

This also causes uneven wear on the clutch outer 2a, clutch inner 3, roller 5, etc., which eventually leads to clutch slip, making it impossible to transmit motor power to the engine. Further, even in the case of transitioning to an overrun state, if the roller 5 bites unevenly, the roller 5 cannot be smoothly separated, which may result in seizing or motor burnout.

On the other hand, the clutch outer 2a shown in FIG.
and the rigidity balance of the clutch inner 3. That is, according to the analysis example shown in FIG.

This corresponds to the combination of the triangle marks and the solid line, and is designed to match the displacement angles of the clutch outer 2a and the clutch inner 3 with respect to the unit distributed load. As a result, roller 5
To provide a roller clutch that enables uniform load distribution, is effective in preventing the above-mentioned defects, has good torque transmission characteristics and overrun performance as a clutch function, and has excellent wear resistance. I can do it.

〔Effect of the invention〕

As shown in the present invention, by balancing the rigidity of the clutch outer and clutch inner, the axial load applied to the rollers during torque transmission is equalized, resulting in stable torque transmission and smooth transition to overrun. Effects such as improved wear resistance and prevention of seizure can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a starter roller clutch according to an embodiment of the present invention, Fig. 2 is an enlarged load distribution diagram of the main part of Fig. 1, and Fig. 3 is a longitudinal sectional view of a conventional roller clutch. FIG. 4 is a load distribution diagram that is an enlarged view of the main part of FIG. 3, and FIG. 5 is a displacement diagram when a unit distribution load is applied to the roller clutch, analyzed by the finite element method. 1... Pinion shaft, 2... Clutch sleeve, 2a... Clutch outer, 2b... Spline tube, 2c... Helical spline, 3... Clutch inner, 4... Pinion, 5... Laura, 6...
Washer, 7... Seal member, 8... Clutch cover.

Claims (1)

[Claims] 1. A clutch outer that is helically spline engaged with the output shaft driven by the motor of the starter for starting the engine, a clutch inner that forms a wedge space with the inner circumference of the clutch outer and is integrally molded with the pinion, and the wedge space. A starter roller that is housed in the wedge space and engages the clutch outer and the clutch inner in one rotation direction in a wedge manner, and a push spring that is housed in the wedge space and constantly presses the roller in the narrow direction of the wedge. The one-way roller clutch is characterized in that the rigidity of the clutch outer and clutch inner is balanced so that the load distribution received in the axial direction of the roller when the clutch outer and the clutch inner are engaged in wedge engagement is uniform. Roller clutch for starters.