JP2001347330A - Manufacturing method of hydraulic automatic tensioner for timing belt tension adjustment of automobile engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a hydraulic automatic tensioner for timing belt tension adjustment of automobile engine capable of improving wear resistance of a valve sleeve without increasing costs. SOLUTION: One of the following methods is adopted. A method to form a valve sleeve by a process to form a bottomed cylindrical shape by press- working a plate stock and a press working process to finish the formed part within a prescribed dimensional tolerance. A method to form the valve sleeve by a process to form the bottomed cylindrical shape by press-working the plate stock and a turning operation process to finish the formed part within the prescribed dimensional tolerance. A method to form the valve sleeve by conducting one process of press-working for both a process to form the plate stock to the bottomed cylindrical shape and a process to finish the formed part within the prescribed dimensional tolerance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a hydraulic auto-tensioner for adjusting a timing belt tension of an automobile engine, and more particularly to a method of manufacturing a valve sleeve.

[0002]

2. Description of the Related Art As a hydraulic auto-tensioner of this type, as shown in FIG. 1, a bottomed tubular valve sleeve 2 is inserted into an outer cylinder 1 and a working oil formed in the valve sleeve 2 is removed. A plunger 4 having a check valve 7 is slidably mounted in the liquid chamber 3, and a rod 5 connected to the plunger 4 is connected to a tension adjusting spring 6 incorporated in the outer cylinder 1.
There is a device which is urged in the exit direction.

In this auto tensioner, when the load acting on the plunger 4 via the rod 5 increases,
The check valve 7 closes the flow passage 8 provided in the plunger 4, and the hydraulic oil leaks from a gap between the plunger 4 and the valve sleeve 2 to exert a buffering action.

In the above structure, the clearance between the plunger 4 and the valve sleeve 2 from which the hydraulic oil leaks must be controlled on the order of several tens of microns, and high precision is required for their processing. In particular, since the valve sleeve 2 must constitute a pressure chamber of the hydraulic damper and always support the sliding plunger 4, a structure free from deformation and material defects is required.

[0005]

Conventionally, as shown in FIG. 3, processing of the valve sleeve 2 is carried out by finishing the bar material 20 through rough turning and finish turning. On the other hand, the plunger 4 is formed to have a high surface hardness by quenching and grinding, but if there is a difference in hardness between the plunger 4 and the valve sleeve 2,
In the long-term durability evaluation, there is a possibility that the abrasion resistance of the two may be shifted.

For this reason, it is desired to improve the hardness (abrasion resistance) of the valve sleeve 2. However, if heat treatment is performed after finishing turning to increase the hardness, the valve sleeve is thin, so There is a problem that deformation easily occurs. On the other hand, a method of increasing the hardness of the material itself by using a tempered material or the like for the bar material 20 is also considered, but this increases the cost of the material and increases the difficulty of processing due to the increased hardness. There is.

Further, the method of forming the valve sleeve from the bar material by turning as described above has a problem that the yield of the material is poor because most of the material is removed as chips.

Therefore, the present invention solves the above-mentioned problems and provides a method of manufacturing a hydraulic auto-tensioner for adjusting the tension of a timing belt of an automobile engine, which can improve the wear resistance of a valve sleeve without increasing the cost. It is intended to provide.

[0009]

In order to solve the above-mentioned problems, the present invention relates to a liquid chamber formed by inserting a bottomed cylindrical valve sleeve into an outer cylinder and forming the liquid chamber in the valve sleeve. A plunger that slides on the inner wall of the valve sleeve, forms a leak gap between the inner wall of the valve sleeve and the plunger, and the plunger is provided with a liquid flow passage and a check valve for opening and closing the liquid passage. In a method of manufacturing a hydraulic auto-tensioner for adjusting a timing belt tension of an automobile engine, which incorporates a tension adjusting spring that urges a rod connected to the plunger in a direction coming out of an outer cylinder, inside a cylinder, The above-mentioned valve sleeve is formed in a step of pressing and forming into a cylindrical shape with a bottom and a step of pressing in order to finish the formed article to a predetermined dimensional tolerance. A method of forming the valve sleeve by a method of processing, and a step of pressing a plate material to form a bottomed cylinder and a turning step of finishing the formed product to a predetermined dimensional tolerance. ,
Alternatively, a method is employed in which the valve sleeve is formed by performing a single step of press forming a step of forming a plate material into a bottomed cylindrical shape and a step of finishing the formed product to a predetermined dimensional tolerance. .

[0010]

As described above, by forming the valve sleeve by press working, the surface hardness is increased by work hardening at the time of pressing, and the wear resistance of the sleeve surface can be improved. In addition, since the work surface becomes smooth due to the ironing action of the forming die and the material at the time of pressing, the surface roughness is improved compared to the turning product, and the frictional resistance to sliding of the plunger can be reduced. it can.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic structure of a hydraulic auto-tensioner for adjusting timing belt tension of an automobile engine manufactured by the present invention is the same as that shown in FIG. Is characterized in that the valve sleeve 2 is formed by press working.

As shown in FIG. 2, the valve sleeve 2 is formed by pressing (rough) a plate material 10 as a raw material.
To form a cylindrical shape with a bottom, and the intermediate molded product is finished to a predetermined dimensional tolerance by press working (finishing).

The valve sleeve 2 needs to be provided with a step 11 for receiving the plunger 4 on the inner peripheral surface in a molded state, and the press working (rough, finish) corresponds to the internal shape of the valve sleeve. Use a forming die with a step. In the press working, the die is slid in a direction approaching and moving away from the plate material 10,
Is pressed to the outer periphery of the die to perform press working.

As described above, the surface of the valve sleeve 2 is subjected to a large work hardening by being formed while being subjected to the ironing action by the forming die, and the hardness of the surface is increased. For example, even when a raw material of S45C is used for the plate material 10, the surface of the valve sleeve after the press working is S53C.
And a hardness comparable to that of a tempered material of SCM material, and can exhibit the same wear resistance.

The surface of the valve sleeve 2 is smoothed by the ironing action of the die, and the surface roughness can be greatly improved as compared with a turned product. FIG.
FIG. 5 shows the surface roughness of the processed surface after press working, while FIG. 5 shows the surface roughness of the processed surface after finish turning. As shown in FIGS. 4 and 5, feed points of the tool are continuously formed on the processed surface after the turning process, and severe irregularities are generated. No feed stitches are formed, the entire surface is smoothed and formed, and the surface roughness is remarkably improved as compared with a turned product. Since the surface of the valve sleeve 2 is smooth as described above, the frictional resistance generated between the valve sleeve 2 and the sliding plunger 4 is significantly reduced,
The wear resistance is improved.

In FIG. 2 described above, press working (rough)
Although the example in which the valve sleeve 2 is finished to a predetermined dimensional tolerance from the plate material 10 by press working (finishing) is shown, finishing turning is performed instead of press working (finishing), and finishing is performed to a predetermined dimensional tolerance by turning. It may be. Also in this case, the hardness of the surface of the valve sleeve is increased and the surface roughness is improved by the processing hardness and the processing smoothness by the press processing (rough), so that the wear resistance can be improved.

Further, the valve sleeve need not necessarily be finished by two steps of press working (roughness and finish), and the valve sleeve may be finished by one press working if a predetermined dimensional tolerance can be satisfied.

[0018]

As described above, according to the manufacturing method of the present invention,
The valve sleeve is formed by pressing to increase the hardness and surface roughness of the sleeve surface, greatly improving the abrasion resistance of the valve sleeve and the durability of a hydraulic auto tensioner for adjusting the timing belt tension of automobile engines. Can be improved.

Further, by press-molding the valve sleeve, the yield of the material is improved, the processing time can be shortened, and the production cost can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a hydraulic auto tensioner.

FIGS. 2A to 2C are views showing examples of molding a valve sleeve according to an embodiment;

3A to 3C are diagrams showing examples of molding a conventional valve sleeve.

FIG. 4 is a view showing the surface roughness of a processed surface after press working.

FIG. 5 is a view showing the surface roughness of a machined surface after turning.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer cylinder 2 Valve sleeve 3 Liquid chamber 4 Plunger 5 Rod 6 Tension adjusting spring 7 Check valve 8 Flow passage

Claims (3)

[Claims] 1. A valve sleeve formed in a cylindrical shape with a bottom is inserted into an outer cylinder, and a plunger sliding on an inner wall of the valve sleeve is attached to a liquid chamber formed in the valve sleeve. A leak gap is formed between the inner wall of the sleeve and the plunger, and the plunger is provided with a liquid flow passage and a check valve for opening and closing the passage, and a rod connected to the plunger is pulled out of the outer cylinder inside the outer cylinder. In a method of manufacturing a hydraulic auto-tensioner for adjusting a timing belt tension of an automobile engine, which incorporates a tension adjusting spring biasing in a direction, the valve sleeve is formed into a bottomed cylindrical shape by pressing a plate material of a material. A timing belt for an automobile engine, comprising a process and a press working process of finishing the molded product to a predetermined dimensional tolerance. Manufacturing method of hydraulic auto tensioner for tension adjustment. 2. A valve sleeve formed in a cylindrical shape with a bottom is inserted into an outer cylinder, and a plunger sliding on an inner wall of the valve sleeve is attached to a liquid chamber formed in the valve sleeve. A leak gap is formed between the inner wall of the sleeve and the plunger, and the plunger is provided with a liquid flow passage and a check valve for opening and closing the passage, and a rod connected to the plunger is pulled out of the outer cylinder inside the outer cylinder. In a method of manufacturing a hydraulic auto-tensioner for adjusting a timing belt tension of an automobile engine, which incorporates a tension adjusting spring biasing in a direction, the valve sleeve is formed into a bottomed cylindrical shape by pressing a plate material of a material. And a turning process for finishing the molded product to a predetermined dimensional tolerance. Manufacturing method of hydraulic auto tensioner for force adjustment. 3. A valve sleeve formed in a cylindrical shape with a bottom is inserted into an outer cylinder, and a plunger sliding on the inner wall of the valve sleeve is attached to a liquid chamber formed in the valve sleeve. A leak gap is formed between the inner wall of the sleeve and the plunger, and the plunger is provided with a liquid flow passage and a check valve for opening and closing the passage, and a rod connected to the plunger is pulled out of the outer cylinder inside the outer cylinder. A method of manufacturing a hydraulic auto-tensioner for adjusting the tension of a timing belt of an automobile engine incorporating a tension adjusting spring biased in a direction, wherein the valve sleeve is formed by molding a plate material of a material into a bottomed cylindrical shape; A timing belt tension adjusting oil for an automobile engine, wherein the step of finishing the product to a predetermined dimensional tolerance is performed by a single step of press working. Manufacturing method of pressure type auto tensioner.