JP5086171B2 - Hydraulic auto tensioner - Google Patents

Description

  The present invention relates to a hydraulic auto-tensioner used for adjusting the tension of a belt for driving an automobile auxiliary machine such as an alternator, a water pump, and an air conditioner compressor.

  As shown in FIG. 4, in a belt transmission device for transmitting the rotation of the crankshaft of an engine to various automobile accessories, a swingable pulley arm 33 for supporting a tension pulley 32 is provided on the slack side of the belt 31, and the pulley arm The adjustment force of the hydraulic auto tensioner A is applied to 33 to urge the pulley arm 33 in the direction in which the tension pulley 32 presses the belt 31 so that the tension of the belt 31 is kept 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, the lower part of the rod is slidably inserted into the sleeve rising from the inner bottom surface of the bottomed cylinder filled with hydraulic oil to form a pressure chamber in the sleeve, which is provided at the upper part of the rod. A return spring is incorporated between the spring seat and the bottom surface of the cylinder to urge the rod and the cylinder in the extending direction.

  Also, a cylindrical dust cover that covers the upper outer periphery of the cylinder and a cylindrical spring cover that covers the upper part of the return spring are 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 elastically contacted with the outer periphery of the spring cover to form a reservoir chamber hermetically sealed between the cylinder and the sleeve, the lower portion of the reservoir chamber communicates with the pressure chamber through a passage, a check valve is provided in the passage, and the belt 31 When a pressing force in the direction of contracting the cylinder and rod is applied to the hydraulic auto tensioner A via the tension pulley 32 and the pulley arm 33, the check valve is closed and the hydraulic oil sealed in the pressure chamber is removed from the inner diameter surface of the sleeve. In the pressure chamber due to the viscous resistance of the hydraulic fluid at the time of flow. By generating a pressure damper force is adapted to buffer the pushing force.

Japanese Patent Laid-Open No. 10-141453

  By the way, in the conventional hydraulic auto tensioner, since the dust cover and the spring cover are separate from the spring seat, there are many inconveniences such as a large number of parts, troublesome assembly, and high cost.

  An object of the present invention is to provide a hydraulic auto tensioner that reduces the number of parts and is easy to assemble and inexpensive.

  In order to solve the above-mentioned problems, in the present invention, a sleeve rising from the inner bottom surface is provided in a cylinder having a closed end at the lower part and filled with hydraulic oil, and the lower end of the rod is provided in the sleeve. A pressure spring is formed in the sleeve by slidably inserting the part, and a return spring that urges the cylinder and rod in the extending direction is incorporated between the spring seat provided on the top of the rod and the inner bottom surface of the cylinder. A cylindrical dust cover that covers the upper outer periphery of the cylinder is provided on the spring seat, and a cylindrical spring cover that covers the upper portion of the return spring, and the inner periphery of the sealing member incorporated in the upper opening of the cylinder is a spring cover. The reservoir chamber and the pressure chamber are communicated with each other by closing the upper opening of the reservoir chamber formed between the cylinder and the sleeve. In a hydraulic auto tensioner provided with a check valve that closes the passage when the pressure in the pressure chamber becomes higher than the pressure in the reservoir chamber, the spring seat is a molded product of aluminum or resin, and the dust cover is formed when the spring seat is molded. And a spring cover are integrally formed, the entire outer periphery of the spring cover is covered with a press-formed steel plate cylinder, and an outward flange formed at the upper end of the cylinder is inserted into the spring seat. Adopted.

  Here, if a tapered portion that is inclined obliquely upward is provided on the outer periphery of the flange, since the tapered portion is embedded in the spring seat, the coupling force between the spring seat and the cylindrical body can be increased. This is effective in preventing the drop-out of the material. Moreover, it can suppress that the burr | flash of aluminum or resin generate | occur | produces in the lower surface outer peripheral part of a flange.

  In addition, if an inward flange that covers the lower end surface of the spring cover is provided at the lower end of the cylinder, and a roundness is provided at the intersection of the lower surface of the flange and the outer peripheral surface of the cylinder, the inner side of the seal member The spring cover can be easily inserted, and when the sealing member has a dust lip on the inner periphery, it is possible to prevent the dust lip from curling inward and to provide good sealing performance. Can be secured.

  Furthermore, the durability can be improved and the sealing performance can be improved by subjecting the cylindrical body to rust prevention and anticorrosion treatment or wear resistance treatment. Here, electroplating, electroless plating, chemical conversion treatment, etc. can be adopted as rust prevention and anticorrosion treatment, and gas soft nitriding, salt bath soft nitriding, carburizing, carbonitriding as wear resistance treatment. Such processing can be adopted.

  As described above, in the present invention, since the spring seat is a molded product of aluminum or resin, and the dust cover and the spring cover are integrally molded when the spring seat is molded, the number of parts is reduced, and the assembly performance is reduced. It is possible to provide an inexpensive hydraulic auto tensioner with excellent cost.

  In addition, since the entire outer periphery of the spring cover is covered with a press-formed steel tube cylinder, the entire inner periphery of the seal member can be brought into good elastic contact with the outer peripheral surface of the cylinder body and has excellent sealing properties. A hydraulic auto tensioner can be obtained.

  Furthermore, by inserting an outward flange provided at the top of the cylinder into the spring seat, the cylinder does not separate from the spring seat, and a hydraulic auto tensioner with excellent durability can be obtained. it can.

  Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the cylinder 1 is closed at the lower portion, and a connecting piece 2 that is rotatably connected to the engine block is provided at the closed end portion.

  A sleeve fitting hole 3 is provided on the inner bottom surface of the cylinder 1, and a lower end portion of the sleeve 4 is press-fitted into the sleeve fitting hole 3. The lower part of the rod 5 is slidably inserted into the sleeve 4, and the pressure chamber 6 is provided in the sleeve 4 by the insertion of the rod 5.

  A spring seat 7 is fixed to an upper end portion of the rod 5 located outside the cylinder 1, and a return spring 8 incorporated between the spring seat 7 and the bottom surface of the cylinder 1 extends relative to the cylinder 1 and the rod 5. It is energizing in the direction to do.

  A connecting piece 9 connected to the pulley arm 33 shown in FIG. 4 is provided at the upper end of the spring seat 7. The spring seat 7 is formed of a molded product, and a cylindrical dust cover 10 covering the outer periphery of the upper portion of the cylinder 1 and a cylindrical spring cover 11 covering the upper portion of the return spring 8 are simultaneously molded to form the spring seat 7. It is integrated.

  Here, the spring seat 7 may be an aluminum die-cast molded product, or may be a molded product of a resin such as a thermosetting resin.

  The entire outer periphery of the spring cover 11 is covered with a cylindrical body 12 that is insert-molded when the spring seat 7 is molded. The cylinder 12 is made of a press-formed product of a steel plate. As shown in FIGS. 2 and 3, the cylindrical body 12 is insert-molded so that an outward flange 13 is provided at the upper end thereof, and the lower surface of the flange 13 is flush with the lower surface of the spring seat 7, A tapered portion 14 provided on the outer peripheral portion of the flange 13 and facing obliquely upward is embedded in the spring seat 7.

  Further, an inward flange 15 that covers the lower end surface of the spring cover 11 is provided at the lower end of the cylindrical body 12, and a roundness 16 is provided at the intersection of the lower surface of the flange 15 and the outer peripheral surface of the cylindrical body 12. Yes.

  As shown in FIG. 2, an oil seal 17 as a seal member is incorporated in the upper opening of the cylinder 1, and an oil lip 18 and a dust lip 19 formed on the inner periphery of the oil seal 17 are connected to the outer periphery of the cylinder 12. The surface is elastically contacted to close the upper opening of the cylinder 1 to prevent the hydraulic oil filled in the cylinder 1 from leaking to the outside and to prevent dust from entering the inside.

  By incorporating the oil seal 17, as shown in FIG. 1, a sealed reservoir chamber 20 is formed between the cylinder 1 and the sleeve 4. The reservoir chamber 20 and the pressure chamber 6 communicate with each other through a passage 21 formed between the fitting surfaces of the sleeve fitting hole 3 and the sleeve 4, and a check valve 22 provided at the end of the passage 21 on the pressure chamber 6 side. When the pressure in the pressure chamber 6 becomes higher than the pressure in the reservoir chamber 20, the passage 21 is closed.

  The rod 5 is formed with a ring groove 23 at a lower end portion located in the sleeve 4, and a retaining ring 24 fitted in the ring groove 23 is brought into contact with a step portion 25 formed on the inner periphery of the sleeve 4. The rod 5 is prevented from being pulled out.

  The hydraulic auto tensioner shown in the embodiment has the above-described configuration. When adjusting the tension of the accessory driving belt 31 shown in FIG. 4, the connecting piece 2 provided at the closed end of the cylinder 1 is connected to the engine block. In addition, the connecting piece 9 of the spring seat 7 is connected to the pulley arm 33, and an adjustment force is applied to the pulley arm 33.

  In the tension adjustment state of the belt 31 as described above, when the tension of the belt 31 changes due to a load change of the auxiliary machine and the tension of the belt 31 becomes weak, the cylinder 1 and the rod 5 are expanded by the pressing of the return spring 8. The slack of the belt 31 is absorbed by relative movement in the direction.

  Here, when the cylinder 1 and the rod 5 move relative to each other in the extending direction, the pressure in the pressure chamber 6 becomes lower than the pressure in the reservoir chamber 20, so the check valve 22 opens the passage 21. For this reason, the hydraulic oil in the reservoir chamber 20 smoothly flows from the passage 21 into the pressure chamber 6, and the cylinder 1 and the rod 5 smoothly move relative to each other in the extending direction to immediately absorb the slack of the belt 31.

  On the other hand, when the tension of the belt 31 is increased, a pushing force in a direction of contracting the cylinder 1 and the rod 5 of the hydraulic auto tensioner from the belt 31 is loaded. At this time, since the pressure in the pressure chamber 6 becomes higher than the pressure in the reservoir chamber 20, the check valve 22 closes the passage 21.

  Further, the hydraulic oil in the pressure chamber 6 flows into the minute clearance 26 formed between the inner diameter surface of the sleeve 4 and the outer diameter surface of the rod 5, flows into the reservoir chamber 20, and the hydraulic fluid flowing into the minute clearance 26. The hydraulic damper generates a hydraulic damper force in the pressure chamber 6 due to the viscous resistance, and the hydraulic damper force buffers the pushing force applied to the hydraulic auto tensioner, and the cylinder 1 and the rod 5 have a pushing force and a return spring. Relatively moves slowly in the direction of contraction to the position where the elastic force of 8 is balanced.

  When adjusting the tension of the belt 31 by the relative expansion and contraction of the cylinder 1 and the rod 5, the lips 18 and 19 of the oil seal 17 slide on the outer peripheral surface of the cylindrical body 12. At this time, since the cylindrical body 12 is a press-formed product of a steel plate and the outer peripheral surface has a high degree of cylindricity, the entire inner periphery of each lip 18, 19 is in good contact with the outer peripheral surface of the cylindrical body 12, No foreign matter such as dust enters inside.

  As shown in the embodiment, an inward flange 15 that covers the lower surface of the spring cover 11 is provided at the lower end of the cylindrical body 12, and a roundness 16 is formed at an intersection where the lower surface of the flange 15 and the outer peripheral surface of the cylindrical body 12 intersect. When the auto tensioner is assembled, the spring cover 11 can be smoothly inserted into the inside of the oil seal 17. Further, there is no inconvenience that the dust lip 19 is folded inward when the spring cover 11 is inserted, and a good sealing property can be ensured.

  Further, since the spring seat 7 is a molded product and the dust cover 10 and the spring cover 11 are integrally molded when the spring seat 7 is molded, the number of parts can be reduced, and the cost of the assembly is excellent. A cheap hydraulic auto tensioner can be obtained.

  Here, if the outer peripheral surface of the cylinder 12 is subjected to rust prevention and anticorrosion treatment such as electroplating, electroless plating, chemical conversion treatment, etc., the corrosion of the cylinder 12 can be prevented and durability can be improved. . In addition, if the tube 12 is subjected to gas soft nitriding, salt bath soft nitriding, carburizing, carbonitriding, or the like instead of the rust prevention and anticorrosion treatment as described above, the hardness of the cylinder 12 can be increased. It is possible to prevent the cylindrical body 12 from being worn by contact with the oil seal 17.

A longitudinal front view showing an embodiment of a hydraulic auto tensioner according to the present invention Sectional drawing which expands and shows a part of FIG. Partially cutaway perspective view showing a cylinder Front view showing a tension adjusting device for an auxiliary machine driving belt

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 4 Sleeve 5 Rod 6 Pressure chamber 7 Spring seat 8 Return spring 10 Dust cover 11 Spring cover 12 Cylindrical body 13 Outward flange 14 Taper part 15 Inward flange 16 Roundness 17 Oil seal (seal member)
20 Reservoir chamber 21 Passage 22 Check valve

Claims (7)

A cylinder that has a closed end at the bottom and is filled with hydraulic oil inside is provided with a sleeve that rises from its inner bottom surface. The lower end of the rod is slidably inserted into the sleeve, and the pressure chamber is inserted into the sleeve. A return spring that urges the cylinder and the rod in a direction to extend is incorporated between a spring seat provided at the upper portion of the rod and the inner bottom surface of the cylinder, and a cylindrical shape that covers the outer peripheral upper portion of the cylinder in the spring seat. A dust cover and a cylindrical spring cover that covers the upper portion of the return spring are provided, 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 spring cover so that the cylinder and the sleeve are in contact with each other. The upper opening of the formed reservoir chamber is closed, and the pressure in the pressure chamber is higher than the pressure in the reservoir chamber in the passage communicating the reservoir chamber and the pressure chamber. In hydraulic auto-tensioner having a and closes the passage check valve,
The spring seat is a molded product of aluminum or resin, and the dust cover and the spring cover are integrally formed when the spring seat is molded, and the entire outer periphery of the spring cover is covered with a press-formed steel plate cylinder, A hydraulic auto tensioner, wherein an outward flange formed at an upper end of a cylindrical body is inserted into the spring seat.   The hydraulic auto tensioner according to claim 1, wherein a tapered portion is provided on the outer periphery of the flange so as to face obliquely upward.   3. The hydraulic system according to claim 1, wherein an inward flange that covers a lower end surface of a spring cover is provided at a lower end portion of the cylindrical body, and a round portion is formed at an intersection between the lower surface of the flange and the outer peripheral surface of the cylindrical body. Auto tensioner.   The hydraulic auto tensioner according to any one of claims 1 to 3, wherein the cylindrical body is subjected to rust prevention and anticorrosion treatment.   The hydraulic auto tensioner according to claim 4, wherein the rust prevention and anticorrosion treatment comprises a kind of electroplating, electroless plating, and chemical conversion treatment.   The hydraulic auto tensioner according to any one of claims 1 to 3, wherein the cylindrical body is subjected to wear resistance treatment.   The hydraulic auto tensioner according to claim 6, wherein the wear resistance treatment is one of gas soft nitriding, salt bath soft nitriding, carburizing, and carbonitriding.

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