JPH0893866A - Driving force supplying device - Google Patents

Abstract

PURPOSE: To provide a driving force supplying device capable of constantly providing proper thrust and smoothing movement of a shaft. CONSTITUTION: A fluid in a cylinder chamber 2 is made to flow through a check valve 9 by allowing a front part 18 and a rear part 19 of the cylinder chamber 2 to communicate with, each other by the check valve 9 provided in a shaft 4. As the fluid passes the check valve 9 when the shaft 4 moves forward and backward, the shaft 4 can speedily advances in the A direction and slowly retreats in the B direction. A floating piston to partition outside air is provided in the cylinder chamber 2, and volume change in the cylinder chamber 2 following advance and retreat of the shaft 4 is absorbed by movement of the floating piston.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a propulsive force applying device for applying a propulsive force to a shaft in order to give a tension to a timing chain for an engine.

[0002]

2. Description of the Related Art Conventionally, this type of propulsive force applying device is disclosed in, for example, Japanese Utility Model Laid-Open No. 58-6034. That is, in this technique, as shown in FIG. 3, a shaft chamber 44 having openings at both ends is provided through a case 43 inserted into the insertion hole 42 of the engine case 41, and one end of the shaft chamber 44 has an inner peripheral surface. Screw 45 is engraved, shaft chamber 4
A shaft 46 that is non-rotatable and slidable in the axial direction is inserted into the shaft 4, and a large number of rack teeth 47 in the direction orthogonal to the axial direction are formed in the axial flat portion formed on a part of the outer peripheral surface of the shaft 46. The shaft 46 is engraved and meshes with the rack teeth 47.
A pawl member 49, which is biased by a spring 48 so as to allow sliding in one direction, and which blocks sliding in the other direction of the shaft 46, is pivotally supported on the case 43, and one end of the shaft 46 is provided with a timing chain. A shoe 51 that presses against 50 to give a constant tension thereto is attached, and a push-out spring 53 having a length longer than that length is inserted into a bottomed hole 52 at the other end opening provided in the shaft center of the shaft 46, and the screw A bolt 55 is screwed into 45 with a gasket 54 interposed therebetween, and the push-out spring 53 is elastically mounted between the bolt 55 and the bottom portion of the bottomed hole 52 to provide a shaft 46.
It is designed to give propulsion to.

[0003]

However, in the conventional propulsive force applying device, the shaft is always urged in such a direction as to be ejected from the case. There is the inconvenience of having to release the urging force of. In addition, since it has a ratchet mechanism consisting of rack teeth and claw members to prevent the shaft from retracting, when the chain, belt, etc. are stretched, the shaft cannot retract and the tension becomes abnormally high. There is a defect.

Further, since it is a ratchet mechanism, in order to maintain the strength in the meshed state, it is necessary to open the rack teeth and enlarge the claw members, which inevitably causes the shaft to move in stages. is there. Furthermore, since it is a ratchet mechanism, there is inevitably rattling, and this rattling causes noise. On the other hand, since the shaft is ejected by a single spring, there is a problem that the biasing force is different between when the shaft is extended and when the shaft is contracted.

Therefore, the present invention eliminates the need for disassembling at the time of assembling, and always provides the chain or belt with an appropriate tension.
An object of the present invention is to provide a propulsion force imparting device which enables smooth movement of the shaft, always keeps the biasing force of the spring constant, improves the strength at low cost, and enhances the flexibility of spring design.

[0006]

In order to achieve the above-mentioned object, according to the present invention, a shaft is inserted into a case so as to be able to advance and retreat in the axial direction by being biased by an extruding spring, and the propulsive force is applied to the shaft by the extruding spring. In the propulsive force applying device, a cylinder chamber is provided with a sealing member interposed between the shaft and the case, a piston portion is provided on the shaft, and a cylinder chamber front portion is provided on the cylinder chamber front portion. And a floating piston that separates the outside air from each other, and the inside of the shaft communicates between the front and rear portions of the cylinder chamber partitioned by the piston portion to move the fluid from the rear portion to the front portion of the cylinder chamber. And a check valve for preventing movement in the opposite direction is provided.

Further, the present invention is characterized in that the cylinder chamber of this propulsive force applying device is filled with silicone grease. Furthermore, the present invention is characterized in that the check valve is provided with an orifice so that a small amount of fluid can pass through the orifice even when the valve is closed.

[0008]

The propelling force is applied to the shaft that can move back and forth by the pushing spring. Therefore, a constant tension is applied to the chain, timing belt, etc. by the propulsive force of this shaft.
In the advancing direction of the shaft, the check valve allows the fluid (silicone grease or the like) in the cylinder chamber to freely pass therethrough, so that the shaft can always be advanced by the urging force of the pushing spring. However, when the shaft is overloaded to push it back, the shaft tries to retract. At this time, since the check valve impedes the movement of the fluid in the cylinder chamber in the backward movement direction of the shaft, the check valve is slightly moved backward by an amount corresponding to the leakage of the fluid in the check valve (claim 1).

Further, in the invention of claim 2, since silicon grease is used as the fluid in the cylinder chamber,
It stabilizes against temperature changes, especially temperature rise, and the forward and backward movements of the shaft become particularly smooth. In the invention of claim 3, since the orifice of the check valve determines the amount of movement of the fluid when the shaft retreats, that is, restricts the movement of the shaft, the dimensional shape of the orifice is changed so that the movement of the shaft retreat is used. Can be adjusted to suit.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view showing an embodiment of a propulsion force applying device of the present invention, and FIG. 2 is a perspective view showing a check valve of this device. In FIG. 1, reference numeral 1 denotes a cylindrical case provided with a cylinder chamber 2, and a flange 3 for attaching to an engine case or the like (not shown) is provided on the outer periphery of an intermediate portion thereof. A shaft 4 having an outer end provided with a shoe portion 4a that is in sliding contact with a chain, a belt or the like is housed in the cylinder chamber 2 so as to be movable in the axial direction. A piston portion 5 is provided at an intermediate portion of the shaft 4 so as to be slidable on the inner surface of the cylinder chamber 2. The shaft 4 penetrates the front portion of the case 1 and slides in the through hole 6. It is held movably.

Reference numeral 7 denotes an end ring that closes the rear portion of the cylinder chamber 2. An extruding spring 8 is mounted between the inner end surface of the end ring 7 and the rear end surface of the piston portion 5 to push the shaft 4 in the forward direction ( It is biased to arrow A). A check valve 9 is provided inside the shaft 4. That is, a conical valve seat 11 is formed in the bottom of a hole 10 bored in the shaft 4 from the rear side, and a valve body 12 is formed in the valve seat 12 there.
3 (see FIG. 2) are opposed to each other, and the valve body 1 is provided by a spring 15 elastically mounted between the valve body 12 and the holed bush 14.
2 is biased to the valve seat 11. The holed bush 14 is press-fitted and fixed in the hole 10.

The relationship between the check valve 9 and the cylinder chamber 2 will be further described. The shaft 4 is provided with holes 16 and 17 which are connected to the valve seat 11 and communicates with the front portion 18 of the cylinder chamber 2, while the rear end of the shaft 4 is provided with the holes 1 and 17.
0 and the rear part 1 of the cylinder chamber 2 containing the pushing spring 8
The groove 20 communicates with the groove 9. Therefore, the cylinder chamber front part 18 and the rear part 19 are connected to each other through the holes 16 and 17, the check valve 9, the hole of the bush 14 with holes, the hole 10 containing the bush 14 with holes, and the groove 20. Become.

Further, in order to maintain airtightness between the cylinder chamber 2 and the outside, a sliding surface between the shaft 4 and the cylinder chamber 2,
A sealing member 22 such as an O-ring is fitted between the end ring 7 and the case 1, and the end ring 7 is prevented from being pulled out by a retaining ring 23 attached to the case 1. 24 is an O-ring 25 at the center of the end ring 7,
This screw 24 is a screw that is screwed with a washer 26.
Can be removed to replenish the fluid in the cylinder chamber 2.

Reference numeral 21 is a floating piston which divides the cylinder chamber front portion 18 from the outside air, and 27 is a piston portion 5
And an O-ring fitted on the outer circumference of the piston 21.
Further, between the floating piston 21 and the shaft 4, there is an O-ring 29 on the inner circumference of the piston 21. This floating piston 2
The first purpose is to absorb the volume change of the cylinder chamber 2 as the shaft 4 moves back and forth. In addition, 30 is a passage leading to the outside air.

In this embodiment, the fluid used to fill the cylinder chamber 2 is silicon grease whose properties do not change much even when the temperature changes. The valve body 12 of the check valve described above is provided with an orifice 28 as shown in FIG. 2, and fluid is allowed to gradually pass through the valve through the orifice 28 even when the valve is closed.

The propulsive force applying device having the above structure is assembled to the engine case or the like with the flange 3, the shoe portion 4a is brought into contact with the chain or the like, and the chain or the like is given a required tension by the spring force of the pushing spring. When the chain or the like becomes loose, the shaft 4 is further advanced by the pushing spring 8 (arrow A in FIG. 1) to maintain the contact between the chain and the shoe portion 4a.
Silicon grease in the front part 18 of the cylinder chamber will move to the rear part 19 through the check valve 9. During this movement, the silicon grease passing through the check valve 9 pushes the valve body 12 against the spring 15 to widen the passage, but the passage is not so wide, and the viscous resistance makes the movement of the shaft 4 less agile. . Changing the silicone grease to another fluid will change the way it works.

When the chain or the like stretches and presses the shoe portion 4a, the shaft 4 tries to retract (arrow B in FIG. 1), but the silicone grease moves backward from the rear portion of the cylinder chamber 2 to the front portion. There must be. At this time, the silicone grease presses the valve body 12 against the valve seat 11 in the hole 10 and can flow only through the orifice 28. Since the cross-sectional area of the orifice 28 is small, the movement of the silicone grease is slow and therefore the shaft 4
In the B direction is much slower than in the A direction. This movement can be variously changed by changing the silicone grease to another fluid or changing the size and shape of the orifice 28. The movement of the shaft 7 in either direction is smooth and smooth due to the viscous resistance of the fluid (silicon grease) in the cylinder chamber 2, and when a gap is formed between the shoe portion 4a and the chain, the gap is quickly and smoothly followed to fill the gap. When the shoe portion 4a is overloaded from a chain or the like, the shoe portion 4 retracts little by little while generating a cushioning force.

[0018]

As described above, according to the propulsion force imparting device of the present invention, the check valve provided on the shaft controls the movement of the fluid in the cylinder between the front and rear of the piston portion, and when the shaft moves forward. It follows smoothly with moderate damping force, and when it retreats, it gradually retreats with stronger damping force, so a smooth propulsion force can always be applied. In addition, the low frequency component of the external excitation force is well tracked to maintain the propulsion force, and the high frequency component is stopped to be absorbed to prevent expansion of noise and loosening and damage of various parts of the machine.

If silicon grease is used as the fluid in the cylinder chamber, the damping force is strong, and the damping force does not fluctuate even when the temperature of the chain or the like becomes high, so that a more stable propulsive force can be applied. If the check valve is provided with an orifice, the damping force at the time of retreating the shaft can be changed by adjusting the size and shape of the orifice, so that an optimum damping force can be provided.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an example of a propulsive force applying device of the present invention.

FIG. 2 is a perspective view of the valve body in FIG.

FIG. 3 is a vertical sectional view showing an example of a conventional propulsive force applying device.

[Explanation of symbols]

 1 Case 2 Cylinder Chamber 4 Shaft 5 Piston Section 8 Extrusion Spring 9 Check Valve 21 O Ring (Sealing Member) 22 O Ring (Sealing Member) 28 Orifice

Claims (3)

[Claims] 1. A propulsion force applying device in which a shaft is inserted into a case by an extruding spring so as to be able to advance and retreat in the axial direction, and a propulsive force is applied to the shaft by the extruding spring. A cylinder chamber with a sealing member interposed between the shaft and a piston part on the shaft, and a floating piston for partitioning the cylinder chamber front part and the outside air at the cylinder chamber front part. Is a check valve that communicates between the front and rear parts of the cylinder chamber partitioned by the piston part to prevent the fluid from moving from the rear part of the cylinder chamber to the front part and to freely move in the opposite direction. A propulsion force imparting device characterized by being provided with. 2. The propulsion device according to claim 1, wherein the cylinder chamber is filled with silicon grease. 3. The propulsive force applying device according to claim 1, wherein the check valve is provided with an orifice so that a small amount of fluid can pass through the orifice even when the valve is closed.