JP2003139206A - Hydraulic belt tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic belt tensioner stabilizing the compression side damping force. SOLUTION: The hydraulic belt tensioner 10 includes a piston 15 furnished with an oil passage 31 to communicate the piston rod side oil chamber 16A with the piston side oil chamber 16B, wherein the oil passage 31 is equipped with a pressure side damping force generation device 32 to work when the piston rod 14 is in the contraction stroke, and further the arrangement includes an oil passage 41C which communicates the piston side oil chamber 16B in with an oil sump chamber 17, a check valve 44 to be opened when the piston rod 14 is elongated, and also an oil passage 18D to communicate the piston rod side oil chamber 16A in with the oil sump chamber 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic belt tensioner for applying an appropriate tension to a winding member such as an endless V-shaped belt, toothed belt, flat belt or chain.

[0002]

2. Description of the Related Art As a hydraulic belt tensioner, as described in JP-A-9-203447, a bottomed cylindrical casing, a cylindrical cylinder concentrically provided in the casing, and a casing A piston rod that slidably enters the cylinder through the open end and the open end of the cylinder with a predetermined clearance; a high-pressure chamber formed between the inner peripheral surface of the cylinder and the end surface of the piston rod; It has been proposed to provide a low pressure chamber formed between the outer peripheral surface and the inner peripheral surface of the casing. When the tension of the belt suddenly increases and the piston rod is about to be compressed, the working oil in the high pressure chamber is configured to flow out to the low pressure chamber through the clearance, and a damper effect is generated. When the tension of the belt suddenly decreases and the piston rod tries to expand, the hydraulic oil in the low-pressure chamber flows into the high-pressure chamber through the check valve provided on the end wall of the cylinder, so that the oil in the high-pressure chamber is quickly oiled. Is replenished.

As another hydraulic belt tensioner, as described in Japanese Utility Model Laid-Open No. 5-14712, a cylinder that is internally filled with oil and is arranged vertically is provided. The oil chamber is slidably fitted to a portion of the cylinder below the first oil chamber.
A piston divided into an oil chamber and a lower third oil chamber, a piston rod provided on the third oil chamber side of the piston and penetrating an end wall of the cylinder on the third oil chamber side, and protruding downward, a first oil chamber, and A first oil passage provided between the second oil chambers to allow an oil flow in the direction from the first oil chamber to the second oil chamber but to block an oil flow in the opposite direction;
Is provided between the second oil chamber and the third oil chamber to allow the oil flow in the direction from the third oil chamber to the second oil chamber but block the oil flow in the opposite direction. It has been proposed to have a second one-way valve. When the tension of the belt suddenly increases and the piston rod is about to be compressed, the two one-way valves close, the second oil chamber between them becomes high pressure, and the high pressure oil causes the piston and the cylinder to move. Slowly flows to the first oil chamber and the third oil chamber through the gap and the like, and the damper effect is generated. When the tension of the belt suddenly decreases and the piston rod tries to expand, the pressure of the third oil chamber rises, and the oil flows from the third oil chamber to the second oil chamber through the second one-way valve. Thus, the second oil chamber is quickly replenished with oil.

[0004]

The hydraulic belt tensioner disclosed in Japanese Patent Laid-Open No. 9-203447 has the following problems.

The compression side damping force is generated by the piston rod compressing the oil in the high pressure chamber, but it is difficult to increase the cross-sectional area of the piston rod forming the pressure receiving surface for the oil in the high pressure chamber, which is large. It is difficult to generate the compression side damping force. Therefore, the belt tension cannot be reliably suppressed.

During compression of the piston rod, the oil in the high pressure chamber flows through the clearance (gap) between the cylinder and the piston rod into the low pressure chamber at a high flow velocity and flow rate, and is vigorously ejected into the air above the oil in the low pressure chamber. Then, the air is entrained, and the oil entrained in the air may soon enter the high pressure chamber from the low pressure chamber, and the pressure side damping force may become unstable. Therefore,
Special measures are required to prevent air from getting into the oil.

Further, the hydraulic belt tensioner disclosed in Japanese Utility Model Laid-Open No. 5-14712 has the following problems.

When the piston rod 20 extends, the flow of the hydraulic oil opens the two second one-way valves 29, and the third
It flows from the oil chamber 19 to the second oil chamber 18, and the piston rod 20
At the time of compression of, through the part between the second oil chamber 18 and the piston 17 and the peripheral wall of the cylinder 10, the part between the piston 17 and the piston rod 20 and the nut 21, and the part of the second one-way valve 29. It slowly flows into the third oil chamber 19. As a result, the flow of the hydraulic oil is reversed between the time when the piston rod 20 is extended and the time when the piston rod 20 is compressed with the piston 17 interposed therebetween, and a bidirectional flow occurs.

Similarly, when the piston rod 20 extends, the flow of hydraulic fluid opens the two first one-way valves 26 to flow from the first oil chamber 16 to the second oil chamber 18, and the piston rod 20 At the time of compression of 20, the portion between the second oil chamber 18 and the cylindrical member 15 and the rivet 27, the first one-way valve 2
It slowly flows through the portion 6 to the first oil chamber 16. Therefore, the flow of the hydraulic oil is reversed between the time when the piston rod 20 is extended and the time when the piston rod 20 is compressed with the cylindrical member 15 interposed therebetween, and a bidirectional flow occurs.

As a result, in the hydraulic belt tensioner described in Japanese Utility Model Laid-Open No. 5-14712, it is easy to mix air into the oil or to deposit air from the oil, which makes the compression side damping force unstable. There is a risk.

Both the hydraulic belt tensioner described in Japanese Patent Laid-Open No. 9-203447 and the hydraulic belt tensioner described in Japanese Utility Model Laid-Open No. 5-14712 use a piston rod or a piston and a cylinder as a compression side damping force generating mechanism. The clearance between them is used. Therefore, the damping force can be generated only by the clearance, and the variation of the damping force characteristic is small. Further, when used in an environment such as an internal combustion engine where the temperature changes drastically, the compression damping force is affected by the change in the viscosity of the oil passing through the clearance and is not stable.

An object of the present invention is to stabilize the compression side damping force in a hydraulic belt tensioner.

[0013]

According to a first aspect of the present invention, in a hydraulic belt tensioner, an inner cylinder is provided in an outer cylinder whose one end is closed, and an inner cylinder is provided from an opening on the other end side of the outer cylinder. The piston rod is slidably inserted, and the piston fixed to the insertion end of the piston rod into the inner cylinder allows the piston rod side oil chamber to accommodate the piston rod inside the inner cylinder and the piston side oil chamber not to accommodate the piston rod. Partition the room,
An oil reservoir is formed between the inner cylinder and the outer cylinder, and a seal member that seals the piston rod-side oil chamber and the oil reservoir is provided in the opening on the other end side of the outer cylinder, and the piston rod-side oil chamber is attached to the piston. And an oil passage that communicates with the piston-side oil chamber, a pressure-side damping force generator that operates when the piston rod contracts is provided in the oil passage, and an oil passage that connects the piston-side oil chamber and the oil reservoir chamber is provided, A check valve that opens when the piston rod extends is provided in the oil passage, and an oil passage that connects the piston rod side oil chamber and the oil reservoir chamber is provided.

According to a second aspect of the present invention, in addition to the first aspect, the compression side damping force generating device is a plate valve.

According to a third aspect of the present invention, in addition to the second aspect of the invention, the plate valve has an annular shape and its inner peripheral side is fixed.

According to a fourth aspect of the present invention, in addition to the first aspect of the invention, the check valve is a plate valve.

According to a fifth aspect of the present invention, in addition to the fourth aspect of the invention, the plate valve has an annular shape, and flow passages can be formed on both the outer peripheral side and the inner peripheral side.

According to a sixth aspect of the present invention, the coil spring for urging the piston rod in the extension direction is interposed between the outer cylinder and the piston rod in the first aspect. A protective cover is provided on the outer circumference of the coil spring.

[0019]

According to the invention of claim 1, the following effects are obtained. The cross-sectional area of the piston that compresses the oil in the piston-side oil chamber to generate the compression-side damping force is larger than the cross-sectional area of the piston rod, so that the pressure receiving area of the piston can be increased and a large compression-side damping force can be generated. Therefore, the tension of the winding member can be surely suppressed.

Oil in the piston side oil chamber, which becomes high pressure when the piston rod is compressed, indirectly flows into the oil reservoir chamber via the piston rod side oil chamber. Therefore, the oil does not jet into the air above the oil reservoir, the air is prevented from being caught in the oil, and the compression-side damping force can be stabilized.

The flow of the hydraulic oil is a one-way flow that returns from the piston side oil chamber to the piston side oil chamber via the piston rod side oil chamber and the oil reservoir chamber both when the piston rod is compressed and when it is extended. Therefore, it is difficult for air to mix with oil,
The compression side damping force can be stabilized.

According to the invention of claim 2, there is the following action. By adopting the plate valve as the compression side damping force generating device, the damping force characteristic depends only on the oil pressure. Therefore, the variation of the damping force characteristic can be diversified by selecting the deflection characteristic of the plate valve. Further, since the damping force characteristic of the plate valve depends only on the oil pressure and does not depend on the oil viscosity, it is possible to stabilize the compression side damping force even in a use environment in which the viscosity of the internal combustion engine changes drastically.

According to the invention of claim 3, there is the following action. Since the inner peripheral side of the above-mentioned annular plate valve is fixed, a high compression side damping force can be generated and the tension of the winding member can be surely suppressed. Further, the closing force of the plate valve is strong, the responsiveness when the piston rod changes from the compression side to the extension side is good, and the looseness of the winding member can be quickly followed.

According to the invention of claim 4, there is the following action. By using a plate valve as a check valve, a larger pressure receiving area can be secured as compared with a ball valve, and the responsiveness when the piston rod extends is good, and the looseness of the winding member can be swiftly followed. Further, the negative pressure in the piston-side oil chamber can be quickly released, and the generation of bubbles can be reduced.

According to the invention of claim 5, there is the following action. Since the flow passages are formed on both the outer peripheral side and the inner peripheral side of the above-mentioned annular plate valve, the return flow passage from the oil reservoir chamber to the piston side oil chamber becomes the inner and outer peripheral two regions, and the flow passage area increases, Negative pressure in the piston side oil chamber can be quickly eliminated. Further, the looseness of the winding member can be quickly followed.

According to the invention of claim 6, there is the following action. A protective cover was provided on the outer circumference of the coil spring. Therefore, the coil spring is not exposed, and the workability of attaching and adjusting the hydraulic belt tensioner can be improved. Also,
Dust can be prevented from entering and scratches on the outer peripheral surface of the piston rod can be prevented.

[0027]

1 is a sectional view showing a compressed state of a hydraulic belt tensioner, FIG. 2 is a sectional view showing an expanded state of a hydraulic belt tensioner, and FIG. 3 is an enlarged sectional view showing a compression side damping force generator. FIG. 4 is an enlarged cross-sectional view showing the check valve, FIG. 5 shows a rod guide, (A) is a cross-sectional view,
(B) is a bottom view, FIG. 6 shows a piston, (A) is a sectional view, (B) is a plan view, and FIG. 7 shows a bottom piece.
(A) is a cross-sectional view, (B) is a plan view, (C) is a bottom view, and FIG. 8 is a schematic view showing an example of a usage state of a hydraulic belt tensioner.

The hydraulic belt tensioner 10 is used, for example, as shown in FIG. In FIG. 8, 1 is a winding member, 2 is a pulley, 3 is an arm, and 4 is an idler pulley. A hydraulic belt tensioner 10 is connected to an intermediate point of the arm 3 supported by a fulcrum 3A, and A play pulley 4 is pivotally attached to the other end. The hydraulic belt tensioner 10 applies an appropriate tension to the wrapping member 1 via the idle pulley 4 while being supported by the fixed portion 5.

The hydraulic belt tensioner 10 is shown in FIG.
As shown in FIG. 2, the inner cylinder 1 is placed inside the outer cylinder 11 whose one end is closed.
2 is provided, and from the opening 13 on the other end side of the outer cylinder 11 to the inner cylinder 12
The piston rod 14 is slidably inserted into the inside of the. The piston 15 fixed to the insertion end of the piston rod 14 into the inner cylinder 12 allows the piston rod-side oil chamber 16A for accommodating the piston rod 14 inside the inner cylinder 12.
And the piston-side oil chamber 1 that does not house the piston rod 14.
6B, and the oil storage chamber 17 is provided between the outer cylinder 11 and the inner cylinder 12.
Is formed.

The hydraulic belt tensioner 10 includes an outer cylinder 1
In a state in which the inner cylinder 12 in which a bottom piece 41 to be described later is fitted is seated upright inside 1, the rod guide 18 and the seal member 19 are inserted into the opening 13 of the outer cylinder 11,
The rod guide 18 and the seal member 19 are sandwiched between the retaining ring 21 attached to the inner periphery of the inner cylinder 12 and the end surface of the inner cylinder 12.

The rod guide 18 is constructed as shown in FIG. 5, and has an outer peripheral portion 18A fitted to the outer cylinder 11, an annular recess 18B fitted to the inner cylinder 12, and an inner portion slidably supporting the piston rod 14. Circumferential portion 18C, piston rod side oil chamber 16
An oil passage 18D is formed by cutting out at a plurality of positions (4 positions) in the circumferential direction of the outer peripheral portion 18A so that A and the oil storage chamber 17 are communicated with each other.

The seal member 19 is composed of an oil seal, is arranged outside the rod guide 18, and seals the piston rod side oil chamber 16A and the oil reservoir chamber 17.

The hydraulic belt tensioner 10 includes an outer cylinder 1
1 is provided with one end attachment portion 22, and the piston rod 14 is provided with the other end attachment portion 23. Further, a spring receiver 24 is formed on the outer circumference of the outer cylinder 11, and the other end attachment portion 2 of the piston rod 14 is formed.
3 is formed on the outer periphery of the spring support 25, and the spring support 2
A coil spring 26 for urging the piston rod 14 in the extending direction is interposed between the No. 4 and the spring receiver 25. Further, a cylindrical protective cover 27 is provided on the outer circumference of the coil spring 26, and an annular mounting portion 27A provided at the end of the protective cover 27 is attached to the spring receiver 25 and the coil spring 2.
The pressure is held between 6 points.

In the hydraulic belt tensioner 10, the piston 15 is provided with an oil passage 31 for communicating the piston rod side oil chambers 16A and 16B, and the oil passage 31 is provided with a pressure side damping force generating device 32 which operates when the piston rod 14 is contracted. ing.
As shown in FIG. 3, the compression-side damping force generating device 32 is configured such that an annular plate valve 35 and a piston 15 are inserted into a small diameter portion of the tip of the piston rod 14 via a spacer 33 and a valve stopper 34 so that the piston rod 14 has a small diameter. The spacer 33, valve stopper 34, and
The plate valve 35 and the piston 15 are fixed. As a result, the plate valve 35 has a valve stopper 34 on the inner side of the ring.
It is sandwiched and fixed by the piston 15. Incidentally, piston 1
5 is configured as shown in FIG.
On the outer circumference.

The hydraulic belt tensioner 10 includes an outer cylinder 1
The bottom piece 41 is fitted to the inner cylinder 12 provided inside the inner casing 1. The bottom piece 41 is configured as shown in FIG. 7, and has an outer peripheral portion 41A that fits into the inner cylinder 12, a flange portion 41B that abuts on the end surface of the inner cylinder 12 and can be seated on the bottom surface of the outer cylinder 11, Plural (4) oil passages 41C and flanges 41B opening to the piston side oil chamber 16B side
An oil groove 41D that is engraved on the end face and that communicates each oil passage 41C with the oil reservoir chamber 17 is provided. That is, the bottom piece 41 connects the piston side oil chamber 16B and the oil reservoir chamber 17 by the oil passage 41C and the oil groove 41D.

The hydraulic belt tensioner 10 includes an inner cylinder 1
Oil chamber 16B on the piston side of the bottom piece 41 fitted in 2
An annular valve seat 43 sandwiched between an outer peripheral stepped portion 42A and an inner peripheral stepped portion 42B is formed on the open end surface of the oil passage 41C facing the check valve 4 which opens when the piston rod 14 extends.
4 is provided on this valve seat 43. Check valve 44
As shown in FIG. 4, a disc spring 47, which is composed of an annular plate valve 45 and is backed up by a retaining ring 46 attached to the inner circumference of the inner cylinder 12, can apply a closing direction force to the plate valve 45. . At this time, the annular plate valve 45 forms a flow path that communicates the oil passage 41C with the piston side oil chamber 16B on both the outer peripheral side and the inner peripheral side in the valve open state.

The hydraulic belt tensioner 10 operates as follows. (1) The hydraulic belt tensioner 10 presses the idler pulley 4 against the winding member 1 by the biasing force of the coil spring 26, and applies a predetermined tension to the winding member 1.

(2) When the tension of the winding member 1 suddenly increases and the piston rod 14 is about to be compressed by the winding member 1, the plate valve 45 of the check valve 44 is closed and the piston side oil chamber 16B is closed. High pressure. The high-pressure oil in the piston-side oil chamber 16B pushes open the plate valve 35 of the pressure-side damping force generator 32 of the piston 15 and slowly flows from the piston rod-side oil chamber 16A to the oil reservoir chamber 17, whereby the pressure-side damping force is increased. Occurs.

(3) When the tension of the winding member 1 is suddenly reduced and the piston rod 14 is about to expand due to the coil spring 26, the piston side oil chamber 16B becomes negative pressure, but the plate valve 45 of the check valve 44 is used. Is immediately opened, and the oil in the oil reservoir 17 is quickly supplied to the piston side oil chamber 16B.

Therefore, according to this embodiment, there are the following effects. The cross-sectional area of the piston 15 that compresses the oil in the piston side oil chamber 16B to generate the compression side damping force is equal to the piston rod 14
It is possible to increase the pressure receiving area of the piston 15 and to generate a large compression side damping force. Therefore, the tension of the winding member 1 can be reliably suppressed.

The oil in the piston side oil chamber 16B, which becomes high pressure when the piston rod 14 is compressed, indirectly flows into the oil reservoir chamber 17 via the piston rod side oil chamber 16A. Therefore, the oil does not jet into the air above the oil reservoir chamber 17, the air is prevented from being caught in the oil, and the compression side damping force can be stabilized.

The flow of hydraulic oil returns from the piston side oil chamber 16B to the piston side oil chamber 16B via the piston rod side oil chamber 16A and the oil reservoir chamber 17 regardless of whether the piston rod 14 is compressed or extended. It becomes a directional flow. Therefore, it is difficult for air to be mixed with oil, and the compression side damping force can be stabilized.

A plate valve 35 is used as a compression side damping force generator.
By adopting, the damping force characteristic depends only on the oil pressure. Therefore, the variation of the damping force characteristic can be diversified by selecting the deflection characteristic of the plate valve 35. Further, since the damping force characteristic of the plate valve 35 depends only on the oil pressure and does not depend on the oil viscosity, it is possible to stabilize the compression side damping force even in an operating environment in which the viscosity changes drastically, such as an internal combustion engine.

Since the inner peripheral side of the above-mentioned annular plate valve 35 is fixed, a high compression side damping force can be generated and the tension of the winding member 1 can be surely suppressed. Further, the valve closing force of the plate valve 35 is strong, the responsiveness is good when the piston rod 14 changes from the compression side to the extension side, and the looseness of the winding member 1 can be quickly followed.

Plate valve 45 as check valve 44
By adopting, it is possible to secure a larger pressure receiving area than that which uses a ball valve, and the piston rod 14
Has good responsiveness when stretched, and can quickly follow looseness of the winding member 1. Further, the negative pressure in the piston side oil chamber 16B can be quickly released, and the generation of bubbles can be reduced.

Since the flow passages are formed on both the outer peripheral side and the inner peripheral side of the annular plate valve 45, the return flow passage from the oil reservoir chamber 17 to the piston side oil chamber 16B becomes the inner and outer peripheral two regions. The road area becomes large, and the negative pressure in the piston-side oil chamber 16B can be quickly eliminated. Further, the looseness of the winding member 1 can be quickly followed.

A protective cover is provided on the outer circumference of the coil spring 26. Therefore, the coil spring 26 is not exposed, and the workability of attaching and adjusting the hydraulic belt tensioner can be improved. Further, it is possible to prevent dust from entering, and prevent the outer peripheral surface of the piston rod 14 from being scratched.

The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and the design can be changed without departing from the gist of the present invention. Etc. are included in the present invention.

[0049]

As described above, according to the present invention, the compression side damping force can be stabilized in the hydraulic belt tensioner.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a compressed state of a hydraulic belt tensioner.

FIG. 2 is a cross-sectional view showing a stretched state of a hydraulic belt tensioner.

FIG. 3 is an enlarged cross-sectional view showing a compression side damping force generating device.

FIG. 4 is an enlarged cross-sectional view showing a check valve.

FIG. 5 shows a rod guide, (A) is a sectional view,
(B) is a bottom view.

FIG. 6 shows a piston, (A) is a sectional view,
(B) is a plan view.

FIG. 7 shows a bottom piece, (A) is a sectional view,
(B) is a plan view and (C) is a bottom view.

FIG. 8 is a schematic view showing an example of a usage state of a hydraulic belt tensioner.

[Explanation of symbols]

10 Hydraulic belt tensioner 11 outer cylinder 12 inner cylinder 14 Piston rod 15 pistons 16A Piston rod side oil chamber 16B Piston side oil chamber 17 oil reservoir 19 Seal member 26 coil spring 27 Protective cover 31 oil passage 32 Pressure side damping force generator 35 plate valve 41C oil passage 44 check valve 45 plate valve

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Claims (6)

[Claims] 1. In a hydraulic belt tensioner, an inner cylinder is provided in an outer cylinder whose one end is closed, and a piston rod is slidably inserted into the inner cylinder from an opening on the other end side of the outer cylinder. The piston fixed to the insertion end of the rod into the inner cylinder separates the piston rod-side oil chamber that houses the piston rod and the piston-side oil chamber that does not house the piston rod inside the inner cylinder. An oil storage chamber is formed between the piston rod side oil chamber and the oil storage chamber, and a seal member for sealing the piston rod side oil chamber and the oil storage chamber is provided in the opening on the other end side of the outer cylinder. An oil passage communicating with the oil passage, a compression side damping force generating device that operates when the piston rod is contracted is provided in the oil passage, an oil passage communicating between the piston side oil chamber and the oil reservoir chamber is provided, and the piston is provided in the oil passage. Check valve that opens when the rod extends The provided hydraulic belt tensioner, characterized in that the piston rod side oil chamber and the oil reservoir chamber is provided an oil passage communicating. 2. The hydraulic belt tensioner according to claim 1, wherein the compression side damping force generating device is a plate valve. 3. The hydraulic belt tensioner according to claim 2, wherein the plate valve has an annular shape, and the inner peripheral side thereof is fixed. 4. The hydraulic belt tensioner according to claim 1, wherein the check valve is a plate valve. 5. The hydraulic belt tensioner according to claim 4, wherein the plate valve has an annular shape, and flow passages can be formed on both the outer peripheral side and the inner peripheral side of the plate valve. 6. A coil spring for urging the piston rod in an extending direction is interposed between the outer cylinder and the piston rod, and a protective cover is provided on an outer periphery of the coil spring. The hydraulic belt tensioner according to any one.