JP2014190425A - Hydraulic auto tensioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic auto tensioner that can suppress drastic reduction in a contact area of a close contact part to a collar due to heat shrinkage of a spring seat after molding and can ensure good sealing performance in the close contact part.SOLUTION: A sleeve 5 is installed within a cylinder 1 in which working fluid is stored, and a spring seat 8 comprising a synthetic resin molded product is installed in an upper part of a rod 6 having a lower end slidably inserted into the sleeve 5. A seal member 14 incorporated into an opening of the cylinder 1 is brought into elastic contact with an outer diameter surface of a metallic collar 13 having an upper part insert-molded to the spring seat 8, so as to form a reservoir chamber 15 within the cylinder 1. An inverted part 13a folded back downwards at approximately 180° is installed at an upper end of the collar 13, so as to increase a contact area to the resin-molded spring seat 8. When the molded spring seat 8 is thermally shrunk, the shrunk resin is brought into close contact with the inverted part 13a to suppress drastic reduction in the contact area of the close contact part, so as to secure airtightness.

Description

  The present invention relates to a hydraulic auto tensioner used for adjusting tension of an auxiliary machine driving belt.

  In a belt transmission that transmits the rotation of the crankshaft of an engine to various automobile auxiliary machines such as an alternator, a water pump, and an air conditioner compressor, as shown in FIG. A movable pulley arm 43 is provided, and the adjustment force of the hydraulic auto tensioner A is applied to the pulley arm 43 so that the rotatable tension pulley 44 supported on the swing side end of the pulley arm 43 presses the belt 41. The pulley arm 43 is biased to keep the tension of the belt 41 constant.

  As a hydraulic auto tensioner A used for the belt transmission as described above, one described in Patent Document 1 has been conventionally known. In this hydraulic auto tensioner, a pressure chamber is formed in the sleeve by slidably inserting the lower part of the metal rod into the inside from the upper opening of the sleeve standing up from the bottom surface of the bottomed cylinder in which the hydraulic oil is accommodated. A return spring is incorporated between a spring seat provided on the upper portion of the rod and the bottom surface of the cylinder to urge the rod and the cylinder in the extending direction.

  In addition, a cylindrical collar that covers the upper part of the return spring is provided at the lower part of the spring seat, and the inner periphery of the seal member incorporated in the upper opening of the cylinder is brought into elastic contact with the outer periphery of the collar and sealed between the cylinder and the sleeve. A reservoir chamber is formed, and the reservoir chamber and the pressure chamber communicate with each other through an oil passage formed at the bottom of the cylinder, and the lower end opening of the sleeve is closed when the pressure in the pressure chamber rises, and the pressure chamber communicates with the oil passage. It incorporates a check valve that shuts off.

  The hydraulic auto tensioner configured as described above connects the connecting piece provided on the lower surface of the cylinder to the engine block so as to be rotatable, and connects the connecting piece provided on the upper surface of the spring seat to the pulley arm 43 shown in FIG. When a pressing force is applied from the belt 41 through the tension pulley 44 and the pulley arm 43 in the direction of contracting the cylinder and the rod, the check valve is closed, and the hydraulic oil sealed in the pressure chamber is supplied to the sleeve and the rod. The fluid is caused to flow through a leak gap formed between the sliding surfaces, and a hydraulic damper force is generated in the pressure chamber by the viscous resistance of the hydraulic oil at the time of the flow to buffer the pushing force.

JP 2009-52652 A

  By the way, in the hydraulic auto tensioner described in Patent Document 1, the spring seat is a molded product of thermosetting resin, and approximately 90 ° toward the outer side provided at the upper end of the collar when the spring seat is molded. The spring seat and the collar are integrated by insert molding the bent part of the spring, but the spring seat and the collar are made of different materials. There is a possibility that a minute gap may be formed between the seat and the collar.

  Here, when a minute gap occurs, when the pressure inside the cylinder rises and a large pressure difference occurs between the inside and outside of the cylinder, the hydraulic oil sealed inside the cylinder leaks outside through the minute gap. The hydraulic auto tensioner cannot function.

  An object of the present invention is to suppress a significant reduction in the contact area of the close contact portion with the collar due to thermal contraction of the spring seat after molding, and to make it possible to ensure a good sealing property at the close contact portion. It is to provide an auto tensioner.

  In order to solve the above problems, in the present invention, a sleeve fitting hole is formed in the bottom upper surface of a bottomed cylinder that contains hydraulic oil, and the lower end of the sleeve is press-fitted into the sleeve fitting hole. A lower end portion of the rod is slidably inserted into the inside from the opening to form a pressure chamber inside the sleeve, and a return spring between a spring seat made of a synthetic resin molded product provided on the upper portion of the rod and the upper surface of the bottom of the cylinder The cylinder and the rod are urged in the extending direction, and the upper part of the metal cylindrical collar covering the upper part of the return spring is insert-molded into the spring seat, and is inserted into the upper opening of the cylinder. An inner periphery of the seal member is elastically contacted with an outer periphery of the collar to form a reservoir chamber between the cylinder and the sleeve, and a fitting surface between the sleeve and the sleeve fitting hole Provided with an oil passage that communicates the reservoir chamber and the pressure chamber, and a check valve that closes when the pressure in the pressure chamber becomes higher than the pressure in the reservoir chamber and shuts off the communication between the pressure chamber and the oil passage in the lower end portion of the sleeve. In the built-in hydraulic auto tensioner, a configuration is adopted in which a reversing portion having a U-shaped cross section folded downward is provided at the upper end portion of the collar located in the spring seat.

  As described above, by providing an inverted portion having a U-shaped cross section at the upper end of the collar, the contact area of the collar with respect to the spring seat is increased compared to the case where the upper end of the collar is bent approximately 90 ° toward the outside. Can be achieved. Even after the resin molding of the spring seat, even if the spring seat contracts, the contraction is contraction in the inner diameter direction, so that the contracted resin is applied to the outer diameter surface of the reversing portion and the outer diameter surface of the upper end portion of the collar. The contact area of the contact portion is not significantly reduced due to the strong contact, and a good sealing property can be ensured at the boundary between the spring seat and the collar.

  Here, if a seal member is provided at the boundary between the inner diameter surface of the collar and the spring seat or the boundary between the outer diameter surface of the collar and the spring seat, the boundary between the spring seat and the collar can be sealed by the seal member. , Better sealing properties can be ensured.

  In addition, when a minute gap is generated at the boundary between the insert-molded collar and the spring seat due to heat shrinkage after the spring seat is molded, the minute gap is impregnated and closed with an impregnating material made of resin. A very good sealing property can be secured at the boundary between the seat and the collar.

  In the hydraulic auto-tensioner according to the present invention, the spring seat may have an inner cylinder portion that extends along the inner diameter surface of the collar and whose entire outer diameter surface is covered with the collar. In that case, a seal member is insert-molded in the lower end portion of the inner cylinder portion and is closely attached to the inner surface of the inward flange formed on the lower end portion of the collar, thereby forming a minute gap on the boundary surface between the inner cylinder portion and the collar. Even if it is made, since the minute gap can be sealed with the sealing member, the effect of preventing leakage of the hydraulic oil can be obtained.

  In the present invention, as described above, by providing the reversal portion having a U-shaped cross section at the upper end portion of the collar, even if the spring seat contracts after resin molding of the spring seat, a relatively large contact is made with the reversal portion. The area can be secured, and a good sealing property can be secured at the boundary between the spring seat and the collar.

1 is a longitudinal sectional view showing an embodiment of a hydraulic auto tensioner according to the present invention. Sectional drawing which expands and shows the insert molding part of the collar of FIG. Sectional drawing which shows the other example of the inversion part formed in the upper end part of a color | collar. (A) thru | or (c) is sectional drawing which shows each example of the sealing means of the boundary part of a spring seat and a collar | collar Sectional drawing which shows the other example of a spring seat Sectional drawing which expands and shows a part of FIG. Front view showing a tension adjusting device for an auxiliary machine driving belt

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the cylinder 1 has a bottom portion, and a connecting piece 2 connected to the engine block is provided on the bottom surface of the bottom portion. The cylinder 1 is made of an aluminum alloy and is formed by die casting.

  The connecting piece 2 is provided with a shaft insertion hole 2a penetrating from one side surface to the other side surface, a cylindrical fulcrum shaft 2b in the shaft insertion hole 2a, and a sliding bearing 2c for rotatably supporting the fulcrum shaft 2b. And the fulcrum shaft 2b is fixed by tightening the bolt 3 that is inserted into the fulcrum shaft 2b and screwed into the engine block E, and the cylinder 1 is swingable about the fulcrum shaft 2b. It is supposed to be installed.

  A sleeve fitting hole 4 is provided in the upper surface of the bottom of the cylinder 1, and a lower end portion of a steel sleeve 5 is press-fitted into the sleeve fitting hole 4. The upper side of the sleeve 5 is opened, and the lower part of the rod 6 is slidably inserted into the inside from the upper opening, and the pressure chamber 7 is provided in the sleeve 5 by the insertion of the rod 6.

  A spring seat 8 is fixed to an upper end portion of the rod 6 located outside the cylinder 1, and a return spring 9 incorporated between the spring seat 8 and the bottom surface of the cylinder 1 extends the cylinder 1 and the rod 6 relatively. It is energizing in the direction to do.

  A connecting piece 10 connected to the pulley arm 43 shown in FIG. 7 is provided at the upper end of the spring seat 8. The connecting piece 10 is formed with a through hole 10a penetrating from one side surface to the other side surface, and a connecting cylinder 10b and a sliding bearing 10c for rotatably supporting the connecting cylinder 10b are incorporated in the through hole 10a. The connecting piece 10 is rotatably connected to the pulley arm 43 by a bolt 11 inserted into the connecting cylinder 10b.

  The spring seat 8 is made of a synthetic resin molded product. Here, a thermosetting resin is employed as the synthetic resin, and a cylindrical dust cover 12 that covers the outer periphery of the upper portion of the cylinder 1 when the spring seat 8 is formed is integrally formed.

  Further, when the spring seat 8 is molded, the upper portion of the cylindrical collar 13 is insert-molded and integrated with the spring seat 8. As shown in FIG. 2, the collar 13 is made of metal, and as shown in FIG. 2, an outward inversion portion 13a having a U-shaped cross section that is folded downward by approximately 180 ° is provided, and the entire inversion portion 13a is a spring. Insert molding is performed in the seat 8.

  As shown in FIG. 1, an oil seal 14 as a seal member is incorporated in the upper opening of the cylinder 1, and the inner periphery of the oil seal 14 is in elastic contact with the outer peripheral surface of the collar 13. The hydraulic oil contained in the cylinder 1 is prevented from leaking to the outside, and the dust is prevented from entering the inside.

  Here, the outer diameter surface of the collar 13 is a sliding portion of the oil seal 14, and if there are scratches or minute protrusions on the sliding portion, the sealing performance is impaired. In order to ensure the sealing performance, after the collar 13 made of cold rolled steel plate (SPCC) is press-molded, it is subjected to surface roughness improvement treatment, and then heat-treated to obtain a surface roughness Ra of 0.4 to 0.6 μm. , Ry is 3 μm, and the surface hardness is 400 to 700 Hv.

  Examples of the surface roughness improving process include barrel polishing, shot blasting, and shot peening.

  By incorporating the oil seal 14, a sealed reservoir chamber 15 is formed between the cylinder 1 and the sleeve 5. The reservoir chamber 15 and the pressure chamber 7 include an oil passage 16 formed between the fitting surfaces of the sleeve fitting hole 4 and the sleeve 5, and an oil sump 17 formed of a circular recess formed at the center of the bottom surface of the sleeve fitting hole 4. It communicates through.

  A check valve 18 is incorporated in the lower end portion of the sleeve 5. When the pressure in the pressure chamber 7 becomes higher than the pressure in the reservoir chamber 15, the check valve 18 cuts off the communication between the pressure chamber 7 and the oil passage 16, and the hydraulic oil in the pressure chamber 7 passes through the oil passage 16 and is stored in the reservoir. The flow into the chamber 15 is prevented.

  The hydraulic auto tensioner shown in the embodiment has the above-described configuration. When adjusting the tension of the accessory drive belt 41 shown in FIG. 7, the connecting piece 2 provided at the closed end of the cylinder 1 is connected to the engine block E. In addition, the connecting piece 10 of the spring seat 8 is connected to the pulley arm 43, and an adjustment force is applied to the pulley arm 43.

  In the tension adjustment state of the belt 41 as described above, when the tension of the belt 41 changes due to the load fluctuation of the auxiliary machine and the tension of the belt 41 becomes weak, the cylinder 1 and the rod 6 are expanded by the pressing of the return spring 9. Relative movement in the direction absorbs slackness of the belt 41.

  Here, when the cylinder 1 and the rod 6 move relative to each other in the extending direction, the pressure in the pressure chamber 7 becomes lower than the pressure in the reservoir chamber 15, so that the check valve 18 is opened. For this reason, the hydraulic oil in the reservoir chamber 15 flows smoothly into the pressure chamber 7 through the oil passage 16, and the cylinder 1 and the rod 6 smoothly move relative to each other in the extending direction to immediately absorb the slack of the belt 41. .

  On the other hand, when the tension of the belt 41 is increased, a pushing force in a direction of contracting the cylinder 1 and the rod 6 of the hydraulic auto tensioner is applied from the belt 41. At this time, since the pressure in the pressure chamber 7 becomes higher than the pressure in the reservoir chamber 15, the check valve 18 is closed.

  Further, the hydraulic oil in the pressure chamber 7 flows into the leak gap 19 formed between the inner diameter surface of the sleeve 5 and the outer diameter surface of the rod 6 and flows into the reservoir chamber 15. A hydraulic damper force is generated in the pressure chamber 7 by the viscous resistance. The pushing force applied to the hydraulic auto tensioner is buffered by the hydraulic damper force, and the cylinder 1 and the rod 6 are slowly moved in such a direction that they are contracted to a position where the pushing force and the elastic force of the return spring 9 are balanced. Move relative.

  In the hydraulic auto tensioner shown in FIG. 1, the spring seat 8 is a molded product of a thermosetting resin, and the collar 13 whose upper portion is insert-molded to the spring seat 8 is made of metal. When heat shrinks, a minute gap that reduces the contact area may be formed in the close contact portion between the spring seat 8 and the collar 13 due to the difference in heat shrinkage. Here, if a gap is formed in the close contact portion between the spring seat 8 and the collar 13, hydraulic oil stored in the cylinder 1 may leak to the outside through the minute gap due to a pressure difference between the cylinder 1 and the outside. There is.

  However, in the embodiment, since the outward inversion portion 13a having a U-shaped cross section is provided at the upper end portion of the collar 13 and the entire inversion portion 13a is insert-molded in the spring seat 8, resin molding When the spring seat 8 is contracted later, the resin comes into close contact with the outer diameter side surface of the reversing portion 13a as shown by a thick dashed line a in FIG. For this reason, the contact area is not significantly reduced, and good sealing performance can be secured at the boundary between the spring seat 8 and the collar 13.

  In FIG. 2, the outward inversion portion 13a is provided at the upper end of the collar 13. However, the inversion portion 13a is not limited to the outward direction, and is an inward inversion portion 13a as shown in FIG. Also good. Even in the case where the reversing portion 13a is directed inward, a close contact portion having a large surface area can be secured between the collar 13 and the spring seat 8 due to thermal contraction of the spring seat 8.

  4A to 4C show an example in which the boundary between the spring seat 8 and the collar 13 is sealed by the sealing means 20. In FIG. 4A, a seal member 21 made of an O-ring is provided at the boundary between the collar 13 and the spring seat 8 on the inner diameter side of the collar 13, and the boundary between the collar 13 and the spring seat 8 is formed by the seal member 21. Is sealed.

  In FIG. 4B, a seal member 21 made of an O-ring is provided at the boundary between the collar 13 and the spring seat 8 on the outer diameter surface side of the collar 13, and the collar 13 and the spring seat 8 are separated by the seal member 21. The boundary is sealed.

  In FIG. 4C, when a minute gap is formed at the boundary between the collar 13 and the spring seat 8 due to thermal contraction after resin molding of the spring seat 8, the impregnation material 22 is made by impregnating the minute gap and made of resin. It is blocked by.

  In any of the sealing means 20 shown in FIGS. 4 (a) to 4 (c), a very good sealing property can be secured at the boundary between the spring seat 8 and the collar 13. FIG.

  4 (a) and 4 (b), the seal member 21 is made of rubber having excellent heat resistance and oil resistance. Examples of such rubber include nitrile rubber, acrylic rubber, silicon rubber, and fluorine rubber. Here, the seal member 21 may be fitted into a ring groove formed in the spring seat 8 or may be insert-molded simultaneously with the formation of the spring seat 8.

  5 and 6 show another example of the spring seat 8. In the spring seat 8 shown in this example, an inner cylinder portion 23 that extends along the inner diameter surface of the collar 13 and is entirely covered with the collar 13 is provided, and a seal member 24 is provided in the lower end portion of the inner cylinder portion 23. The seal member 24 is brought into close contact with the upper surface of the inward flange 13 b formed at the lower end portion of the collar 13 to seal between the lower end portion of the inner cylinder portion 23 and the lower end portion of the collar 13.

  As described above, the inner cylinder portion 23 is provided in the spring seat 8, and the seal member 24 is insert-molded in the lower end portion of the inner cylinder portion 23. Even if a minute gap is formed at the boundary, the sealing member 24 can ensure airtightness. In addition, the length of the minute gap becomes long, and an effect can be obtained in suppressing leakage of hydraulic oil.

DESCRIPTION OF SYMBOLS 1 Cylinder 4 Sleeve fitting hole 5 Sleeve 6 Rod 7 Pressure chamber 8 Spring seat 9 Return spring 13 Collar 13a Reverse part 14 Oil seal (seal member)
15 Reservoir chamber 16 Oil passage 18 Check valve 21 Seal member 22 Impregnating material 23 Inner cylinder portion 24 Seal member

Claims (4)

A sleeve fitting hole is formed in the bottom upper surface of the bottomed cylinder containing the hydraulic oil, and the lower end of the rod is slidably inserted into the sleeve fitting hole from the upper opening of the sleeve press-fitted into the sleeve fitting hole. A pressure chamber is formed inside the sleeve, and a return spring is installed between the spring seat made of a synthetic resin molded product provided on the upper part of the rod and the bottom upper surface of the cylinder to urge the cylinder and rod in the extending direction. Then, the upper part of the metal cylindrical collar covering the upper part of the return spring is insert-molded into the spring seat, and the inner periphery of the seal member incorporated in the upper opening of the cylinder is brought into elastic contact with the outer periphery of the collar. A reservoir chamber is formed between the cylinder and the sleeve, and an oil passage communicating the reservoir chamber and the pressure chamber is provided between the fitting surfaces of the sleeve and the sleeve fitting hole. Only, in the lower end portion of the sleeve, the hydraulic auto-tensioner incorporating a check valve for blocking communication between the pressure chamber and the oil passage is closed and the pressure in the pressure chamber becomes higher than the pressure in the reservoir chamber,
A hydraulic auto tensioner, wherein a reversing portion having a U-shaped cross-section folded downward is provided at an upper end portion of the collar located in the spring seat.   The hydraulic auto tensioner according to claim 1, wherein a seal member for sealing the boundary portion is provided at a boundary portion between the inner diameter surface of the collar and the spring seat or a boundary portion between the outer diameter surface of the collar and the spring seat.   2. The hydraulic auto tensioner according to claim 1, wherein a minute gap formed at a boundary portion between the collar and the spring seat is impregnated by heat shrinkage after resin molding of the spring seat and closed with an impregnating material made of resin.   The spring seat has an inner cylinder portion that extends along the inner diameter surface of the collar and is entirely covered with the collar, and is formed in the lower end portion of the inner cylinder portion at the lower end portion of the collar. The hydraulic auto tensioner according to claim 1, wherein a seal member that is in close contact with the upper surface of the facing flange is insert-molded when the spring seat is molded.

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