JPH07113467A - Accumulator for hydraulic control circuit - Google Patents

Abstract

PURPOSE:To stabilize the performance so that no influence is given to the temperature variation, as for a check valve using a shaft-shaped member. CONSTITUTION:A check valve 4 which permits the flow of air into an atmosphere chamber 1a from a working pressure chamber 1b and suppresses the flow of working oil is installed on a piston 2, and the check valve 4 is constituted of a cylindrical valve cylinder 41 fitted with a through hole 2b which permits the communication between the atmosphere chamber 1a and the working pressure chamber 1b and penetrates through the piston 2 and a shaft-shaped member 42 which is inserted into a fine gap formed and a set between the inner periphery of the valve cylinder 41 and the shaft-shaped member 42, and the valve cylinder 41 and the shaft-shaped member 42 are made of the material having the nearly equal thermal expansion coefficient.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accumulator used in a hydraulic control circuit for an automatic transmission for automobiles.

[0002]

2. Description of the Related Art An automatic transmission uses a hydraulic clutch that operates to shift gears and the like.
An accumulator is arranged in the middle of the oil passage to the clutch drum in order to mitigate the sudden change in the hydraulic pressure.

Conventionally, as such an accumulator for a hydraulic control circuit, for example, one described in Japanese Patent Laid-Open No. 63-308257 is known. The accumulator has a check valve built in the piston that blocks the flow of hydraulic oil from the working pressure chamber to the atmospheric pressure chamber but allows the flow of air in the opposite direction. This check valve is composed of a valve cylinder fitted in a through hole of a piston, a check ball provided in the valve cylinder, and a pin for preventing the check ball from coming off.

Further, in the accumulator as described above, if an air pocket is generated in the working pressure chamber, the engagement delay of the clutch will occur, so a check valve for bleeding air is provided. As a check valve with such a structure,
For example, there is one described in JP-A-56-20855. As shown in FIG. 4, this check valve has a through hole 0 formed in a wall 03 which is defined by two chambers, a first chamber 01 and a second chamber 02.
4 are formed, and a minute gap (for example, 1
A shaft-like member 06 is provided by forming a gap (5 μm to 25 μm) 05. Due to the viscosity of the oil, the minute gap 05 does not allow the oil to pass through, but has the characteristic of allowing the atmosphere to flow. The through hole 04 is provided with a caulking portion 07 for preventing the shaft-shaped member 06 from coming off. Further, in this conventional technique, a check ball 08 is provided inside the shaft-shaped member 06, which prohibits the oil from flowing from the first chamber 01 to the second chamber 02 and allows the fluid to flow in the opposite direction. However, even if this check ball 08 is not provided, it functions as a check valve for preventing air accumulation.

When such an axial member (not including a check ball) 06 is applied to an accumulator for a hydraulic control circuit as described in the former publication, the wall 03 corresponds to a piston and the first chamber 01 Is an operating pressure chamber connected to a hydraulic circuit (not shown) for supplying and discharging hydraulic pressure, and the second chamber 02 corresponds to an atmospheric chamber opened to the atmosphere by a communication passage (not shown). Therefore, in this structure, when the hydraulic pressure is supplied to the first chamber 01, the oil hardly flows out from the minute gap 05 to the second chamber 02 because the viscosity of the oil is large.
The air in the air pool circulates.

[0006]

However, when the check valve formed of the shaft-shaped member as described above is applied to the conventional accumulator for hydraulic control circuit, there are the following problems.

That is, aluminum die casting is mainly used for the piston of the accumulator for the hydraulic control circuit in order to reduce the weight. On the other hand, in consideration of the small shape and durability of the shaft-shaped member,
In order to reduce costs, existing commercially available iron-based metals such as bearing steel or copper-based alloys are used. In this way, when the piston and the shaft-shaped member are made of different materials and have different thermal expansion coefficients, the size of the minute gap formed between the two changes depending on the temperature, and the amount of oil leakage and air The flow rate may change and stable performance may not be obtained.

The present invention has been made by paying attention to such a conventional problem, and in a check valve using a shaft-shaped member, it is possible to stabilize the performance so as not to be affected by temperature change. Has an aim.

[0009]

According to the present invention, a shaft-shaped member is inserted into a valve cylinder and the valve cylinder is fitted into a through hole of a piston, and the shaft-shaped member and the valve cylinder are heated. The materials having the same expansion coefficient are used to achieve the above object.

That is, according to the present invention, the inside of the main body cylinder is
A piston that is slidably inserted inside defines an operating pressure chamber that communicates with the hydraulic control circuit to mitigate changes in hydraulic pressure and an atmospheric chamber that communicates with the atmosphere side. A check valve that allows air to flow from the chamber to the atmospheric chamber but blocks the flow of hydraulic oil is provided in the through hole that communicates the atmospheric chamber with the operating pressure chamber and is penetrated by the piston. It is composed of a tubular valve cylinder fitted and a shaft-shaped member inserted with a minute gap set between the valve cylinder and the inner circumference of the valve cylinder.
The valve cylinder and the shaft-shaped member are made of materials having substantially the same thermal expansion coefficient.

The valve cylinder has a large-diameter portion that fits into the open end of the through-hole, and a diameter smaller than the large-diameter portion. It is also possible to form a small-diameter portion having a gap therebetween and to insert the shaft-shaped member inside the small-diameter portion.

[0012]

When assembled, the shaft-shaped member is inserted into the valve cylinder, and the valve cylinder is fitted into the through hole formed in the piston.

In the accumulator according to the second aspect of the invention, the shaft member is inserted into the small diameter portion of the valve cylinder, and only the large diameter portion of the valve cylinder is fitted into the through hole so that the small diameter portion and the through hole are A gap is formed between the circumference and the circumference. Therefore, even if there is a dimensional error between the valve cylinder and the through hole, when the two are fitted together, the small diameter portion is not compressed due to the formation of the gap between the small diameter portion and the through hole. Absent.

Next, the operation will be described. When a hydraulic pressure is generated in the hydraulic control circuit, this hydraulic pressure is introduced into the working pressure chamber in the main body cylinder, and the piston slides accordingly and the volume of the working pressure chamber is increased. Change. Due to the change in the volume, the increase in the hydraulic pressure of the hydraulic control circuit is alleviated during this period, and the shelf pressure is formed.

At this time, in the check valve, the hydraulic oil in the working pressure chamber tries to flow into the atmosphere chamber from the minute gap between the shaft-shaped member and the valve cylinder due to the pressure difference between the working pressure chamber and the atmosphere chamber. The viscosity of the hydraulic oil prevents this flow.

On the other hand, when an air pool is generated in the working pressure chamber, the air in the working pressure chamber flows into the atmosphere chamber through the minute gap of the check valve.

In the above operation, if the temperature of the hydraulic oil introduced into the working pressure chamber changes, the temperature also changes inside the hydraulic control circuit accumulator.
Due to this temperature change, the dimensions of the piston, the check valve, etc. change based on the coefficient of thermal expansion. At this time, the valve cylinder and the shaft-like member of the check valve are
Since they are made of materials with approximately the same coefficient of thermal expansion, the dimensional change rates of both are approximately the same, and the minute gap formed between them is
A substantially constant size is maintained.

[0018]

Embodiments of the present invention will now be described with reference to the drawings. First, the configuration of the embodiment will be described.

FIG. 1 is a sectional view showing an accumulator for a hydraulic control circuit according to an embodiment of the present invention, in which 1 is a main body cylinder. A piston 2 is slidably inserted into the main body cylinder 1 so that the inside of the main body cylinder 1 is communicated with a hydraulic pressure control circuit (not shown), and an operating pressure chamber 1b for reducing a change in hydraulic pressure, The air chamber 1a is connected to the atmosphere side. The piston 2 is made of aluminum and resin for weight reduction, and is urged by a spring 3 toward the atmosphere chamber 1a.

A check valve 4 is provided at the center of a wall 2a of the piston 2 which defines the atmosphere chamber 1a and the working pressure chamber 1b. The check valve 4 allows the air to flow from the working pressure chamber 1b to the atmosphere chamber 1a but prevents the working oil from flowing. The check valve 4 is provided to connect the atmosphere chamber 1a and the working pressure chamber 1b. To form a minute gap h (FIG. 2) set between the cylindrical valve cylinder 41 fitted into the through hole 2b penetrating the piston 2 and the inner circumference of the valve cylinder 41. And the shaft-shaped member 42 inserted.

This structure will be described in more detail with reference to FIG. 2. The through hole 2b is coaxial with the large diameter hole 2c whose one end is opened on the side of the working pressure chamber 1b and the other end of this large diameter hole 2c. It is configured to communicate with the small diameter hole 2d having one end opened to the atmosphere chamber 1a. And, as shown in the bottom view of FIG.
e is formed.

The valve cylinder 41 has, at one end, a large diameter portion 41a having an outer diameter that fits tightly with the large diameter hole 2c, while a small diameter portion 41b constituting the remaining portion.
Is formed to have a smaller diameter than the large diameter hole 2c so as to form a gap k with the inner circumference of the large diameter hole 2c. A storage hole 41c is formed inside the valve cylinder 41, and an opening end of the storage hole 41c on the large diameter portion 41a side is formed with a small diameter by forming a flange 41d. The flange 41d is also provided with a cross-shaped flow groove 41e similar to the flow groove 2e.

The shaft-like member 42 is inserted into the housing hole 41c of the valve cylinder 41 with a minute gap h formed between it and the inner periphery of the housing hole 41c, and is slidable in the axial direction. Is formed shorter than the axial length of the storage hole 41c. The size of the minute gap h is determined based on the characteristics of the hydraulic oil that flows through the hydraulic control circuit, and is formed to have a size that allows the air to flow but not the hydraulic oil. If it shows, it is about 23-46 micrometers.

The valve cylinder 41 and the shaft-like member 42 are made of ferrous alloy steel having the same coefficient of thermal expansion. In this case, the alloy steel may be made of the same material for the valve cylinder 41 and the shaft-like member 42, or different alloy steels may be used as long as they have substantially the same thermal expansion coefficient.

Next, the procedure for assembling the check valve 4 will be described. First, the shaft-shaped member 42 is inserted into the housing hole 41c of the valve cylinder 41. At this time, a minute gap h is formed between the outer circumference of the shaft-shaped member 42 and the inner circumference of the storage hole 41c. Then, the valve cylinder 41 is inserted into the large diameter hole 2c of the through hole 2b from the small diameter portion 41b, and the large diameter portion 41a is fitted into the large diameter hole 2c.

At this time, the small diameter portion 41 of the valve cylinder 41
Since a gap k is formed between b and the large diameter hole 2c of the through hole 2b, even if there is dimensional variation between the valve cylinder 41 and the through hole 2b, this variation is small in the small diameter portion 41b. The small diameter portion 41b is absorbed by the gap k, and the small diameter portion 41b passes through the through hole 2b.
There is no pressure on the inner circumference.

Next, the operation will be described. When the hydraulic pressure is constantly applied to the chamber A and the hydraulic pressure is generated in the hydraulic control circuit, this hydraulic pressure is introduced into the operating pressure chamber 1b in the main body cylinder 1 to slide the piston 2. As a result, the volume of the working pressure chamber 1b changes. During this volume change, the rise of the hydraulic pressure of the hydraulic control circuit is moderated, and the shelf pressure is formed.

At this time, in the check valve 4, the working oil in the working pressure chamber 1b is forced from the minute gap h between the shaft-like member 42 and the valve cylinder 41 into the atmosphere chamber by the differential pressure between the working pressure chamber 1b and the atmosphere chamber 1a. Although it tries to flow to 1a, this flow is almost blocked by the viscosity of the hydraulic oil.

When air pressure is generated in the working pressure chamber 1b and a pressure difference is generated between the working pressure chamber 1b and the atmosphere chamber 1a, the air in the working pressure chamber 1b is circulated on the large diameter portion 2c side. Groove 4
1e through the minute gap h between the shaft-shaped member 42 and the valve cylinder 41, and further from the circulation groove 2e through the small diameter hole 2d to the atmosphere chamber 1a. By the circulation of this air,
The clutch engagement delay due to air accumulation is eliminated. Also,
In the check valve 4, the shaft-shaped member 42 slides in the axial direction due to the pressure difference between the working pressure chamber 1b and the atmosphere chamber 1a, which prevents clogging of the minute gap h with sludge or the like.

When the temperature of the working oil introduced into the working pressure chamber 1b changes in performing the above operation, the temperature also changes inside the accumulator for the hydraulic control circuit. Then, due to this temperature change, the dimensions of the piston 2, the check valve 4, and the like change based on the coefficient of thermal expansion.

At this time, since the valve cylinder 41 and the shaft-like member 42 of the check valve 4 are made of materials having substantially the same coefficient of thermal expansion, the dimensional change rates of the two are substantially equal to each other. The minute gap h maintains a substantially constant size. Therefore, the leak amount of hydraulic oil and the flow amount of air are kept constant, and stable performance is obtained. Although the piston 2 and the check valve 4 are made of different materials, the degree of dimensional change caused by temperature change is different, but the relative dimensional change between the two is due to the difference between the valve cylinder 41 and the piston 2. It is not absorbed by the gap k and does not press the valve cylinder 41. Therefore, the minute gap h
Does not affect.

As described above, in the hydraulic control circuit accumulator of this embodiment, in the check valve 4, the shaft-shaped member 42 is inserted into the storage hole 4 of the valve cylinder 41.
Since the shaft member 42 and the valve cylinder 41 are made of materials having substantially the same thermal expansion coefficient, they are provided inside 1c, so that the dimension of the minute gap h can be made substantially constant even if the temperature of the hydraulic oil changes. It is possible to obtain the effect that the performance can be stabilized by maintaining the temperature.

Further, only the large diameter portion 41a of the valve cylinder 41 is fitted into the through hole 2b of the piston 2 and the small diameter portion 41b accommodating the shaft-like member 42 is provided between the inner diameter of the through hole 2b. Since the gap k is formed, even if there is a dimensional error between the valve cylinder 41 and the through hole 2b,
When the valve cylinder 41 is press-fitted, the small diameter portion 41b is not pressed and its inner diameter does not change. This also has the effect that the size of the minute gap h can be kept constant.

Further, the large diameter portion 41 of the valve cylinder 41
Since the flange 41d is formed integrally with a so as to prevent the shaft-shaped member 42 from coming off, the number of parts and assembly work are reduced as compared with the case where a separate member such as a pin is provided to prevent the coming off. The effect that can be obtained is obtained.

Although the embodiment of the present invention has been described above with reference to the drawings, the specific configuration is not limited to this embodiment, and even if there is a design change or the like without departing from the scope of the present invention. In the embodiment, which is included in the present invention, the valve cylinder 41 and the shaft-shaped member 42 are made of an iron-based alloy steel having substantially the same thermal expansion coefficient as a raw material. They may be formed of the same material such as aluminum or iron-iron. In this case, they are the same material, so that they have the same thermal expansion coefficient and are preferable.

[0036]

As described above, in the hydraulic control circuit accumulator of the present invention, the check valve provided in the piston is constituted by the shaft-shaped member, and the shaft-shaped member is directly inserted into the through hole of the piston. Instead of doing
Once inserted in the valve cylinder, a minute gap is formed between the valve cylinder and the valve cylinder, and this valve cylinder is fitted into the through hole formed in the piston. Also, the shaft member and the valve cylinder have approximately the same thermal expansion coefficient. Since it is made of a material, even if the temperature of the check valve changes due to the influence of the temperature of the hydraulic oil, the dimensional change due to the temperature change between the shaft-shaped member and the valve cylinder is relatively equal, and it is possible to keep the minute gap approximately constant. Therefore, the effect that the performance can be stabilized can be obtained.

According to the second aspect of the present invention, the small diameter portion of the valve cylinder forming a minute gap with the shaft-like member has a gap with the inner circumference of the through hole of the piston. Since only the large diameter part is fitted into the through hole,
Even if there is a dimensional error between the valve cylinder and the through hole, the small diameter part will not be pressed when they are fitted together, and therefore the size of the minute gap will change due to the pressing during fitting. It is possible to obtain the effect that the performance can be stabilized by this as well.

[Brief description of drawings]

FIG. 1 is a sectional view showing an accumulator for a hydraulic control circuit according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a main part of the accumulator of the embodiment.

FIG. 3 is a bottom view showing a main part of the accumulator of the embodiment.

FIG. 4 is a cross-sectional view showing a conventional technique.

[Explanation of symbols]

 1 Main Body Cylinder 1a Atmosphere Chamber 1b Working Pressure Chamber 2 Piston 2b Through Hole 4 Check Valve 41 Valve Cylinder 41a Large Diameter Part 41b Small Diameter Part 42 Axial Member h Small Gap k Gap

Claims (2)

[Claims] 1. A main body cylinder is provided with an operating pressure chamber that is communicated with a hydraulic control circuit by a piston that is slidably inserted therein to reduce a change in hydraulic pressure, and an atmosphere chamber that is communicated with the atmosphere side. The piston is provided with a check valve that allows the flow of air from the working pressure chamber to the atmosphere chamber but blocks the flow of working oil. The check valve connects the atmosphere chamber and the working pressure chamber. And a cylindrical valve cylinder fitted in a through hole penetrating the piston, and a shaft-shaped member inserted with a minute gap set between the cylindrical valve cylinder and the inner circumference of the valve cylinder. The accumulator for a hydraulic control circuit, wherein the valve cylinder and the shaft-shaped member are made of materials having substantially the same thermal expansion coefficient. 2. The valve cylinder has a large-diameter portion that fits into an opening end of the through-hole, and a diameter smaller than the large-diameter portion. 2. A hydraulic control circuit accumulator according to claim 1, wherein a small-diameter portion having a gap is formed between the small-diameter portion and the shaft-shaped member is inserted inside the small-diameter portion.