Valve timing adjustment device

Abstract

To provide an inexpensive and light valve timing adjusting device.SOLUTION: A valve timing adjusting device 1 is equipped with an annular sprocket 11 that is rotated by being transmitted rotation force from a crank shaft, and a cam shaft gear 12 that is assembled to the sprocket 11, is rotated by being transmitted rotation force from a motor, and is relatively rotated with respect to the sprocket 11. The sprocket 11 has a bridging part 21 formed so as to linearly connect two points on an inner peripheral edge. The cam shaft gear 12 has a stopper portion 12a disposed on the inside of the inner peripheral edge of the sprocket 11. The bridging part 21 is provided at a position on which the stopper portion 12a abuts when a valve timing is in a retard angle state, on the inner peripheral edge of the sprocket 11.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a valve timing control device for an internal combustion engine. [Background technology]

[0002] A valve timing controller is a device for adjusting the timing of opening and closing the intake valve and exhaust valve of an internal combustion engine. In the valve timing controller, a stopper structure is provided on the sprocket and the camshaft to limit their relative rotational motion. This stopper structure functions when, for example, an abnormality occurs in a motor that drives the camshaft to control its position, making it impossible to control the camshaft's position.

[0003] For example, Patent Document 1 discloses the following technology: A retaining plate fixed to a sprocket has a first outer surface and a second outer surface that are inclined with respect to the collision direction. Also, an adapter fixed to a camshaft has an inclined first inner surface and a second inner surface that respectively abut against the first outer surface and the second outer surface of the retaining plate. This type of stopper structure limits the relative rotational movement of the camshaft with respect to the sprocket by the first outer surface and the first inner surface or the second outer surface and the second inner surface abutting against each other. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 071038 Summary of the Invention [Problem to be solved by the invention]

[0005] The stopper structure described above requires a design that ensures rigidity so that it can withstand a load greater than a collision load that may occur in the event of an abnormality. In order to ensure rigidity, it is possible to enlarge the components that make up the stopper structure, for example by increasing their thickness to increase the collision surface. However, if an attempt is made to ensure rigidity by enlarging the size of each component, there is a risk that mounting constraints cannot be satisfied. In addition, there is a problem that the mass and manufacturing costs of the components increase.

[0006] Therefore, an object of the present disclosure is to provide an inexpensive and lightweight valve timing adjusting device. [Means for solving the problem]

[0007] The valve timing adjustment device disclosed herein is a valve timing adjustment device for an internal combustion engine, and includes: an annular sprocket that rotates as a result of rotational force being transmitted from a crankshaft; and a camshaft gear that is assembled to the sprocket, rotates as a result of rotational force being transmitted from a motor, and rotates relative to the sprocket, wherein the sprocket has a bridging portion formed to connect two points on its inner periphery in a straight line, and the camshaft gear has a stopper portion that is positioned inside the inner periphery of the sprocket, and the bridging portion is provided on the inner periphery of the sprocket at a position where the stopper portion abuts when the valve timing is in a retarded state. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide an inexpensive and lightweight valve timing adjusting device. [Brief description of the drawings]

[0009] [Figure 1] 1 is an exploded perspective view showing a configuration of a main part of a valve timing adjusting device according to a first embodiment. FIG. [Diagram 2] 1 is an exploded perspective view showing a part of a main configuration of a valve timing adjusting device according to a first embodiment. FIG. [Diagram 3]1 is a front view showing a stopper structure of a valve timing adjusting device according to a first embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] First embodiment <Configuration of valve timing adjustment device> Hereinafter, an embodiment will be described with reference to the drawings. FIG. 1 is an exploded perspective view showing a main configuration of a valve timing adjusting device 1. FIG. 2 is an exploded perspective view showing a sprocket 11 and a camshaft gear 12 as part of the main configuration of the valve timing adjusting device 1. FIG. 3 is a front view showing a stopper structure of the valve timing adjusting device 1. As shown in FIG. 1, the valve timing adjusting device 1 includes a sprocket 11, a camshaft gear 12, an input rotor 13, a snap ring 14, a first bearing 15, a planetary gear 16, a housing 17, and a second bearing 18. The valve timing adjusting device 1 is a device that adjusts the timing of opening and closing of an intake valve and an exhaust valve of an internal combustion engine. The valve timing adjusting device 1 arbitrarily changes the phase of the camshaft gear 12 relative to the sprocket 11 to adjust the advance or delay of the valve timing.

[0011] The sprocket 11 has a gear portion with which a timing chain meshes on its outer circumferential surface. The sprocket 11 rotates when the torque of the crankshaft is transmitted via the timing chain.

[0012] The sprocket 11 is formed in an annular shape on the inside of which a stopper portion 12a (described later) of the camshaft gear 12 can be arranged. As shown in Figures 2 and 3, the sprocket 11 has an inner circumferential edge that is substantially circular, but a part of the inner circumferential edge is formed in a shape that can cooperate with the stopper portion 12a of the camshaft gear 12 to limit the relative rotational movement with the camshaft gear 12. Specifically, the sprocket 11 has a bridging portion 21 provided on the inner circumferential edge, a linear portion 22 formed to be paired with the bridging portion 21, and a curved portion 23 formed between the bridging portion 21 and the linear portion 22.

[0013] The bridging portion 21 cooperates with the stopper portion 12a of the camshaft gear 12 to form a stopper structure that limits relative rotation with the camshaft gear 12 when the rotation of the camshaft gear 12 stops. The bridging portion 21 is provided at a position on the inner periphery of the sprocket 11 where it abuts against the stopper portion 12a of the camshaft gear 12 when the valve timing is in a retarded state. The bridging portion 21 is also configured to be able to reduce the impact load when the stopper portion 12a collides. The bridging portion 21 is provided on the inner periphery of the sprocket 11 and is formed so as to connect two points on the inner periphery in a straight line. The bridging portion 21 forms a gap with the inner periphery in a middle portion excluding both ends.

[0014] The straight-line portion 22 is formed in a straight line shape as a part of the inner peripheral edge of the sprocket 11. The straight-line portion 22 is a portion that comes into contact with the stopper portion 12a of the camshaft gear 12 when the valve timing is in an advanced state. The straight-line portion 22 is formed symmetrically with the portion of the bridge portion 21 that comes into contact with the stopper portion 12a with respect to a straight line in the radial direction of the sprocket 11 that passes through the center of the curved portion 23, for example.

[0015] The curved portion 23 is formed in a smooth curved shape as a part of the inner peripheral edge of the sprocket 11. The curved portion 23 is located between the bridge portion 21 and the straight portion 22, and is formed to smoothly connect to both the bridge portion 21 and the straight portion 22. The curved portion 23 is formed so that the stopper portion 12a can rotate along the curved portion 23. In other words, the curved portion 23 is formed in a shape corresponding to the trajectory of the tip of the stopper portion 12a when it rotates relative to the camshaft gear 12. The curved portion 23 is formed in a substantially arc shape corresponding to the range in which the stopper portion 12a rotates when the advance or retard is repeated.

[0016] The camshaft gear 12 is fixed to a camshaft (not shown). The camshaft gear 12 is also assembled to a sprocket 11. The camshaft gear 12 has an internal gear portion with which the planetary gear 16 meshes. The camshaft gear 12 rotates by receiving a rotational force from the planetary gear 16. The camshaft gear 12 rotates in conjunction with the camshaft. As shown in Figs. 2 and 3, the camshaft gear 12 has a stopper portion 12a that cooperates with each component of the sprocket 11 to stop relative rotational movement with respect to the sprocket 11 that exceeds a predetermined range.

[0017] The stopper portion 12a is formed integrally with, for example, the camshaft gear 12. As shown in FIG. 3, the stopper portion 12a is disposed inside the inner peripheral edge of the sprocket 11 when assembled with the sprocket 11. The stopper portion 12a rotates relative to the sprocket 11 within a predetermined angular range as the camshaft gear 12 rotates. The stopper portion 12a exerts a stopper function in cooperation with each component provided on the inner peripheral edge of the sprocket 11. As shown in FIG. 3, the stopper portion 12a is formed in an egg shape in a plan view. In other words, the stopper portion 12a is formed in a tapered shape with rounded leading and trailing ends in a plan view. Specifically, the stopper portion 12a has a first side portion 31, a second side portion 32, a leading end portion 33, and a trailing end portion 34, which will be described below.

[0018] The first side portion 31 is formed in a linear shape that abuts against the bridging portion 21. The first side portion 31 is located on the retard side when assembled to the sprocket 11. The first side portion 31 abuts against the bridging portion 21 of the sprocket 11 when the valve timing is in a retarded state. By abutting against the bridging portion 21, the first side portion 31 limits the relative rotational movement of the camshaft gear 12 that exceeds the maximum retard position. For example, when an abnormality occurs in the motor and the rotation of the camshaft gear 12 stops, the first side portion 31 collides with the bridging portion 21 of the rotating sprocket 11, thereby limiting the rotational movement of the camshaft gear 12 relative to the sprocket 11.

[0019] The second side portion 32 is formed in a linear shape that abuts against the linear portion 22. The second side portion 32 is located on the advance side when assembled to the sprocket 11. The second side portion 32 abuts against the linear portion 22 of the sprocket 11 when the valve timing is in an advanced state. By abutting against the linear portion 22, the second side portion 32 limits the relative rotational movement of the camshaft gear 12 that exceeds the maximum advanced position.

[0020] The tip portion 33 is formed in a curved shape with a predetermined curvature. The curvature of the tip portion 33 is set to be larger than the curvature of the curved portion 23. The tip portion 33 is formed to smoothly connect with the first side portion 31 and the second side portion 32. The tip portion 33 is in contact with the curved portion 23, and rotates along the curved portion 23 during relative rotation with the sprocket 11.

[0021] When the first side portion 31 abuts against the bridging portion 21, the tip portion 33 continuously abuts against the bridging portion 21 and a part of the curved portion 23 from one end continuing from the first side portion 31. The tip portion 33 abuts against a part of the bridging portion 21 and a part of the curved portion 23 with almost no gap, for example, at the maximum retard position. For example, the portion of the tip portion 33 continuing from the first side portion 31 is formed in substantially the same shape as the portion of the sprocket 11 that continues from the bridging portion 21 to the curved portion 23.

[0022] Furthermore, for example, when the second side portion 32 abuts against the straight portion 22, the tip portion 33 continuously abuts against part of the straight portion 22 and part of the curved portion 23 from one end continuing from the second side portion 32. For example, at the maximum advance angle position, the tip portion 33 abuts against part of the straight portion 22 and part of the curved portion 23 with almost no gap. For example, the portion of the tip portion 33 continuing from the second side portion 32 is formed in substantially the same shape as the portion of the sprocket 11 that continues from the straight portion 22 to the curved portion 23.

[0023] The rear end 34 is formed in an arc shape. The rear end 34 is formed to smoothly connect to the first side portion 31 and the second side portion 32. The rear end 34 has an arc shape that does not interfere with the structure of the inner circumferential edge of the sprocket 11 during relative rotational movement. In other words, the rear end 34 forms a gap with respect to the inner circumferential edge of the sprocket 11 when assembled to the sprocket 11.

[0024] The input rotor 13 is rotated by the drive of a motor (not shown). The input rotor 13 has a cylindrical eccentric portion whose rotation axis is eccentric with respect to the rotation axis of the camshaft. A snap ring 14 is disposed on an end face of the input rotor 13. The input rotor 13 rotatably supports a planetary gear 16 via a first bearing 15.

[0025] The planetary gear 16 is formed in a cylindrical shape into which the eccentric portion of the input rotor 13 fits. The planetary gear 16 rotates by receiving a rotational force from the input rotor 13. The planetary gear 16 rotates about an axis that is eccentric with respect to the rotation axis of the camshaft. The planetary gear 16 has a large diameter gear portion and a small diameter gear portion on its outer periphery. The large diameter gear portion meshes with an internal gear portion of the housing 17. The small diameter gear portion meshes with an internal gear portion of the camshaft gear 12. Here, the number of teeth of the large diameter gear portion is less than the number of teeth of the internal gear portion of the housing 17, and the number of teeth of the small diameter gear portion is less than the number of teeth of the internal gear portion of the camshaft gear 12.

[0026] The housing 17 has an internal gear portion that meshes with the large diameter gear portion of the planetary gear 16. The housing 17 rotatably supports the input rotor 13 via a second bearing 18. The housing 17 is attached to the sprocket 11 by a plurality of bolts 19. The housing 17 rotates integrally with the sprocket 11.

[0027] <Valve timing adjustment device operation> In the above-described valve timing adjusting device 1, the input rotor 13 is controlled by the motor so as to rotate at the same rotation speed as the sprocket 11. At this time, the camshaft gear 12 does not rotate relative to the sprocket 11, and the camshaft is held at a predetermined phase with respect to the sprocket 11.

[0028] On the other hand, when changing the phase, the input rotor 13 is controlled by the motor to rotate at a rotation speed different from that of the sprocket 11. By making the rotation speed of the input rotor 13 different from that of the sprocket 11, the planetary gear 16 rotates about an eccentric rotation axis and revolves about the rotation axis of the camshaft. This causes the camshaft gear 12 to rotate relative to the sprocket 11. As a result, the phase of the camshaft changes, and the valve timing is adjusted to the advance or retard side.

[0029] Here, the phase of the camshaft changes to the advance side by making the rotation speed of the input rotor 13 greater than the rotation speed of the sprocket 11, and to the retard side by making it smaller. After changing the phase of the camshaft in this way, the rotation speed of the input rotor 13 is made the same as that of the sprocket 11 again, thereby maintaining the phase of the camshaft at a predetermined phase and adjusting the valve timing according to the phase relative to the sprocket 11.

[0030] Here, for example, if an abnormality occurs in the motor driving the input rotor 13 and the rotation speed of the camshaft gear 12 cannot be controlled, the camshaft gear 12 will rotate relatively to the retard side with respect to the sprocket 11. As a stopper structure for the retard side, the first side portion 31 of the stopper portion 12a collides with the bridging portion 21, thereby stopping the relative rotation of the camshaft gear 12 with respect to the sprocket 11. At this time, the bridging portion 21 of the sprocket 11 bends toward the inner peripheral edge side, exerting the effect of a leaf spring, thereby mitigating the impact load at the time of collision. Note that the effect of the leaf spring can be enhanced by ensuring a large length of the bridging portion 21.

[0031] Since such a valve timing adjusting device 1 can withstand the impact load of the stopper structure when it hits the stopper structure, it is not necessary to increase the size of each component constituting the stopper structure, and therefore the valve timing adjusting device 1 can be made inexpensive and lightweight.

[0032] It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0033] 1 Valve timing adjustment device 11 Sprocket 12 Camshaft gear 12a Stopper part 13 Input Rotor 14 Snap ring 15 No. 1 bearing 16 Planetary Gear 17 Housing 18 No. 2 bearing 19 Volts 21 Crosslinked part 22 Straight line section 23 Curved section 31 First side 32 Second Side 33 Tip 34 Rear end

Claims

1. A valve timing control device for an internal combustion engine, comprising: an annular sprocket that rotates when torque from a crankshaft is transmitted; a camshaft gear that is attached to the sprocket and rotates when a rotational force from a motor is transmitted thereto, and that rotates relative to the sprocket; The sprocket has a bridge portion formed so as to linearly connect two points on an inner peripheral edge, the camshaft gear has a stopper portion disposed inside an inner circumferential edge of the sprocket, the bridge portion is provided on an inner peripheral edge of the sprocket at a position where the stopper portion comes into contact when the valve timing is in a retarded state; Valve timing adjustment device.

2. The stopper portion has a linear first side portion that abuts against the bridge portion in the retarded state. The valve timing control device according to claim 1 .

3. The inner peripheral edge of the sprocket has a linear portion formed in a straight line at a position where the stopper portion abuts when the valve timing is in an advanced state.

3. The valve timing adjusting device according to claim 1 or 2.

4. The stopper portion has a linear second side portion that abuts against the linear portion in the advance angle state. The valve timing control device according to claim 3.

5. The gap formed between the bridge portion and the inner peripheral edge is arc-shaped.

3. The valve timing adjusting device according to claim 1 or 2.

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