JPH08312713A - Self-pumping type shock absorber - Google Patents

Abstract

PURPOSE: To restrain change of axial force by decreasing pressure fluctuation for the time that the extending stroke of a piston rod is transferred to the contracting stroke. CONSTITUTION: A self-pumping type shock absorber for performing a pumping function and for adjusting a car height by the extension and the contraction of a piston rod is provided with a first reservoir chamber 30 communicated with an upper liquid chamber 18 demarcated inside a cylinder 10, a second reservoir chamber 32, a first pump means for supplying liquid from the first reservoir chamber to the second reservoir chamber, and a second pump means 36 to be operated when the car height is not more than the specified car height, and for supplying liquid from the second reservoir chamber to the first reservoir chamber. The capacity of a pump chamber 90 of the second pump means is larger than that of a pump chamber of the first pump means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-pumping type shock absorber for automobiles, and more particularly, it has a pump function in addition to the original vibration damping or vibration absorbing function, and the vehicle height is automatically adjusted by this pump function. The present invention relates to a self-pumping type shock absorber.

[0002]

2. Description of the Related Art A cylinder, a piston having a damping force generating mechanism slidably disposed in the cylinder, and a piston rod which is connected to the piston at one end thereof and the other end of which protrudes outward from the cylinder. The shock absorber that has the function of absorbing vibration has a pump function,
A self-pumping type shock absorber that automatically adjusts the vehicle height by this pump function has been proposed (Japanese Patent Laid-Open No. 59-159441).

In the self-pumping type shock absorber, the piston rod is provided with a hollow hole extending in the axial direction from the end of the piston rod connected to the piston, and the pump cylinder is arranged in the hollow hole so that the piston rod projects. A pump rod extending from an end of the cylinder opposite to the end of the pump is inserted into the pump cylinder so as to be relatively movable, and a pump chamber is defined by the pump cylinder and the pump rod. The pump rod has a passage extending in the axial direction, and a low-pressure chamber which is a liquid reservoir communicates with the passage. A high-pressure chamber is provided in addition to the low-pressure chamber, and the high-pressure chamber communicates with the pump chamber via the upper liquid chamber of the two liquid chambers partitioned by the piston.

If the piston rod repeatedly expands and contracts when the vehicle height decreases, the liquid sucked into the pump chamber from the low pressure chamber through the passage is pushed out of the pump chamber to the upper liquid chamber by the action of the valve. As a result, the amount of liquid in the upper liquid chamber and the high-pressure chamber increases, which pushes down the piston and extends the piston rod, thereby adjusting the vehicle height. When a predetermined vehicle height is reached, a control passage, which is provided in the pump rod and connects the passage and the upper liquid chamber, opens,
The liquid in the upper liquid chamber escapes to the low pressure chamber. In this way, the predetermined vehicle height is maintained.

[0005]

In the self-pumping type shock absorber, when the piston rod extends, the pressure in the pump chamber becomes close to the pressure in the low pressure chamber, whereas when the piston rod contracts, the pressure in the pump chamber decreases. The pressure is close to the pressure in the high pressure chamber. Therefore, during the transition from the expansion stroke of the piston rod to the compression stroke, a large pressure fluctuation occurs, and the axial force of the shock absorber changes. The pressure fluctuation can be reduced by bringing the pressure in the low pressure chamber close to the pressure in the high pressure chamber and reducing the pressure difference between the two. However, if the pressure difference is reduced, the vehicle height increases and the control passage moves upward. When the fluid is communicated with the liquid chamber, the velocity of the liquid flowing into the low pressure chamber through the control passage becomes extremely slow, and it takes time to reduce the vehicle height.

The object of the present invention is to reduce the pressure fluctuation during the transition from the expansion stroke to the compression stroke of the piston rod,
It is an object of the present invention to provide a self-pumping type shock absorber capable of suppressing a change in axial force.

[0007]

SUMMARY OF THE INVENTION The present invention comprises a cylinder,
A piston having a damping force generating mechanism, which is slidably arranged in the cylinder and partitions the inside of the cylinder into an upper liquid chamber and a lower liquid chamber, and is connected to the piston at one end,
A self-pumping shock absorber having a piston rod whose other end projects from the cylinder to the outside, and which adjusts the vehicle height by performing a pump function by expansion and contraction of the piston rod, and is provided outside the cylinder. A first reservoir chamber communicating with the upper liquid chamber, a second reservoir chamber provided outside the cylinder, and a liquid supplied from the first reservoir chamber to the second reservoir chamber, A first pump means having a pump chamber and a second pump chamber that works when the vehicle height is equal to or lower than a predetermined vehicle height to supply the liquid from the second reservoir chamber to the first reservoir chamber, and is larger than the first pump chamber. Second pump means having a second pump chamber of capacity.

[0008]

[Operation and effect] When the automobile is running, a damping force is generated by the damping force generating mechanism provided on the piston to absorb the vibration. When the vehicle height is higher than the predetermined vehicle height, the first pump means supplies the liquid from the first reservoir chamber to the second reservoir chamber. As a result, the amount of liquid in the first reservoir chamber and the upper liquid chamber decreases, and the vehicle height decreases. Conversely, when the vehicle height is equal to or less than the predetermined vehicle height, the first pump means supplies the liquid from the first reservoir chamber to the second reservoir chamber, and at the same time, the second pump means causes the second reservoir chamber to supply the liquid. Liquid is supplied from the chamber to the first reservoir chamber. At this time, since the pump chamber of the second pump means has a larger capacity than the pump chamber of the first pump means, the amount of liquid in the first reservoir chamber and the upper liquid chamber increases, and the vehicle height increases. Go up.

In order to forcibly supply the liquid from the first reservoir chamber to the second reservoir chamber and from the second reservoir chamber to the first reservoir chamber by the pump means, the first reservoir chamber Even if the pressure difference between the second reservoir chamber and the second reservoir chamber is zero, the pump function can be performed without any trouble. In this way, since the pressure difference between the first and second reservoir chambers is zero or can be reduced even if there is a pressure difference, the pressure fluctuation occurring in the pump means is small and the axial force change is small. . As a result, the influence on the riding comfort can be substantially eliminated. Further, since the pressure difference can be kept small, it is possible to reduce efficiency reduction due to leakage or the like.

Since it is possible to increase the discharge amount when the pump operates without affecting the riding comfort, it is possible to shorten the time required for adjusting the vehicle height.

[0011]

[Example] The self-pumping type shock absorber
Referring to FIG. 1 partially enlarged and FIG. 2 showing the whole, a cylinder 10, a piston 12, and a piston rod 14 are provided, and in addition to the damping force absorbing function, the piston rod 14 expands and contracts to perform a pumping function. Adjust the vehicle height.

The cylinder 10 is formed of a cylindrical member, and its upper end portion is curved inward. The lower end of the cylinder 10 has a seal cap 1
It is connected to 6.

The piston 12 is slidably arranged in the cylinder 10 in a liquid-tight state, and partitions the inside of the cylinder 10 into an upper liquid chamber 18 and a lower liquid chamber 20. Piston 12
Is a damping force generating mechanism known per se, that is, a passage and a valve 22 that generate a damping force when the piston rod 14 described later extends, and a passage and a valve 24 that generate a damping force when the piston rod 14 contracts. Have.

The piston rod 14 is connected to the piston 12 at one end. The other end of the piston rod 14 passes through the seal cap 16 of the cylinder 10 and projects to the outside. The piston rod 14 is held liquid-tight by an O-ring 26 attached to the seal cap 16, and is movable relative to the seal cap 16.
The piston rod 14 has a stepped hollow 28 extending axially from the end joined to the piston 12.

The pumping type shock absorber is further provided outside the cylinder 10 and communicates with the upper liquid chamber 18, and a second reservoir chamber 32 provided outside the cylinder 10. The first pump means 34 and the second pump means 36 are provided.

In the illustrated embodiment, the cylinder 38 is disposed coaxially with the cylinder 10 outside the cylinder 10.
Two reservoir chambers 30 and 32 are formed using the cylinder 38. The cylinder 38 has an end cap 39.
It is composed of a cylindrical member integrally having. As will be described later, the valve support member 40 is arranged above the cylinder 10, and the partition 42 and the rubber diaphragm 44 are attached to the cylinder 10, and then the cylinder 38 is attached to the cylinder 10.
The end cap 39 against the valve support member 40, the end cap 46 is caulked to the lower end of the cylinder 38, and the seal cap 48 is attached to bring the cylinder 38 into a predetermined attachment state. It is held at intervals.

The partition 42 is an annular member which is press-fitted into the cylinder 10 and vertically partitions the space between the cylinder 38 and the cylinder 10. On the other hand, the diaphragm 44
Is formed in a cylindrical shape as a whole and is longer than the length of the cylinder 38 in the axial direction. The upper end 50, the intermediate part 51, and the lower end 52 of the diaphragm 44 are made thick to be fitted to the valve support member 40, the partition 42, and the end cap 46, respectively, and to receive the compressive force from the cylinder 38. , The diaphragm 44 is kept liquid-tight at three locations spaced apart in the axial direction. As a result, a first space 54 is defined between the valve support member 40 and the partition 42 by the diaphragm 44 and the cylinder 38, and a second space 56 is defined between the partition 42 and the end cap 46. And a cylinder 38. Air, nitrogen gas or an inert gas is enclosed in these spaces 54 and 56, whereby the first reservoir chamber 3
0 is inward of the first space 54 and the second reservoir chamber 3
2 is formed above the second space 56. The first reservoir chamber 30 has a curved end 1 above the cylinder 10.
1 through the clearance between the valve support member 40 and the valve support member 40
It communicates with 8.

The first reservoir chamber 30 has a first space 54.
The pressure of the gas filled in the second reservoir chamber 32 is kept substantially equal to the pressure of the gas filled in the second space 56, and the pressure of the second reservoir chamber 32 is kept substantially equal to the gas pressure filled in the second space 56. In the present invention, since the liquid is forcibly supplied by the pump means as described later, the pressure in the first space 54 and the second space 56.
The pressure can be made equal to that of the above pressure, and the pressure can be set so as to cause a difference between both pressures. In the latter case, the pressure of the first space 54 that pressurizes the first reservoir chamber 30 communicating with the upper liquid chamber 18 is set to be high, and the pressure of the second space 56 is set to be low. This is the first
This is because the liquid chamber 18 is always loaded, so that the stability of the operation is improved and the pressure fluctuation is avoided. The pressure in the first space 54 is set to 980 kPa (10 kgf / cm ² ) or more, for example.

The first pump means 34 supplies the liquid from the first reservoir chamber 30 to the second reservoir chamber 32, and the first pump chamber 60 and the inner pump rod which slides in the pump chamber 60. 62.

In the illustrated embodiment, the pump chamber 60 is formed by a reduced diameter bore portion below the stepped bored hole 28 in the piston rod 14. On the other hand, the inner pump rod 62 has a passage 63 penetrating in the axial direction and is inserted into the pump chamber 60 with a slight clearance. This slight clearance has a size that allows the inner pump rod 62 and the pump chamber 60 to move relative to each other, although liquid does not substantially leak. The inner pump rod 62 has a mount plate 66 attached to the upper end thereof, and the mount plate 66 is attached to the valve support member 40 with a rubber attachment seat 68 interposed. A hole into which the mounting seat 68 can be inserted is opened in the valve support member 40, and after the mounting seat 68 is arranged at a predetermined position, the hole is closed with a lid. The same applies to the arrangement of the valves described below, but the illustration of the holes and the lid not only complicates the drawing but also obscures the main structure, so the holes and lids for the above-mentioned purpose are omitted.

The valve support member 40 has an intermediate chamber 70, and the passage 63 of the inner pump rod 62 communicates with the intermediate chamber 70. The valve support member 40 is provided with two passages 72, 74 extending radially outward from the intermediate chamber 70. Further, the passage 73 connecting the passage 72 to the first reservoir chamber 30 and the passage 74 are connected by a pipe. A passage 75 communicating with the second reservoir chamber 32 through the hole 76 and the partition hole 77.
And are opened in the axial direction of the cylinder 38. The two ends of the pipe 76 are connected to the valve support member 40 and the partition 42.
Are respectively fitted to.

A first check valve 80 is located in passage 72 and a second check valve 82 is located in passage 74. The check valve 80 includes a valve plate 84 and a coil spring 85, and allows only the flow of the liquid from the first reservoir chamber 30 toward the intermediate chamber 70. On the other hand, the check valve 82 similarly includes a valve plate and a coil spring, but has a large spring constant and allows only the flow of the liquid from the intermediate chamber 70 toward the second reservoir chamber 32.

The second pump means 36 operates when the vehicle height is equal to or lower than a predetermined vehicle height to supply the liquid from the second reservoir chamber 32 to the first reservoir chamber 30, and the first pump chamber 6
The second pump chamber 90 having a capacity larger than 0 and the pump chamber 9
0 and an outer pump rod 92 that slides in the interior.

In the illustrated embodiment, the pump chamber 90 is defined by the enlarged bore portion above the stepped bore 28 in the piston rod 14. Pump room 9
0 has a capacity larger than that of the pump chamber 60,
This volume is not the entire volume of the pump chamber itself,
It is the amount that is sucked in or discharged by the expansion and contraction of the piston rod 14 per unit length. On the other hand, the outer pump rod 92 is formed of a cylindrical member having a bottom, and the inner pump rod 62 is fitted into a hole formed in the bottom 93. As a result, the space between the outer pump rod 92 and the inner pump rod 62 is a passage 94. The outer pump rod 92 can be inserted into the annular adjusting portion 116 of the pump chamber 90 with a slight clearance. This slight gap causes virtually no liquid leakage,
The size is such that the outer pump rod 92 and the pump chamber 90 can move relative to each other.

The valve support member 40 has a second intermediate chamber 96, the upper end of the outer pump rod 92 is press-fitted into this intermediate chamber 96, and the passage 94 communicates with the second intermediate chamber 96. . Two passages 98, 100 are provided in the valve support member 40 extending radially outward from the intermediate chamber 96.
The passage 98 communicates with the passage 73, and the passage 100 communicates with the passage 75.

A third check valve 102 is located in passage 98 and a fourth check valve 104 is located in passage 100. The check valve 102, which is composed of a valve plate and a coil spring, has a large spring constant and allows only the flow of the liquid from the intermediate chamber 96 toward the first reservoir chamber 30.
On the other hand, the check valve 104 similarly includes a valve plate and a coil spring, and allows only the flow of the liquid from the second reservoir chamber 32 toward the intermediate chamber 96.

A control hole 110 is formed in the lower end of the outer pump rod 92. The control hole 110 is closed by a sleeve 114 that is biased by a coil spring 112. At a standard predetermined vehicle height, the sleeve 114 is pushed up by the adjusting portion 116 that is located at the end of the hollowed hole 28 of the piston rod 14 and separates the pump chamber 90 from the upper liquid chamber 18, and opens the control hole 110,
A passage 94 is formed so as to communicate with the upper liquid chamber 18 via the control hole 110. Therefore, when the vehicle height becomes equal to or lower than the predetermined vehicle height, the outer pump rod 92 moves into the pump chamber 90.
The passage 94 communicates with the pump chamber 90 through the control hole 110 as it enters the inside and pushes the sleeve 114 upward.

As is known per se, the self-pumping type shock absorber is used by attaching the upper end of the rod 120 projecting upward from the cylinder 38 to the vehicle body and the lower end of the pithron rod 14 to the suspension arm. However, prior to use, the upper liquid chamber 1
8, lower liquid chamber 20, first reservoir chamber 30 and second
The reservoir chamber 32 is filled with oil or other liquid.

When the vehicle is bound when the vehicle is bound,
The piston rod 14 contracts, and a damping force generation mechanism 24 provided in the piston 12 generates a damping force to absorb the vibration. Further, in the rebound state, the piston rod 14 extends and a damping force generation mechanism 22 provided in the piston 12 generates a damping force to absorb the vibration.

When the vehicle height is higher than the predetermined vehicle height, only the first pump means 34 is activated. When the piston rod 14 extends, the pump chamber 60 of the first pump means 34 has a negative pressure, and the first check valve 80 opens but the second check valve 82 closes. As a result, the liquid in the first reservoir chamber 30 reaches the intermediate chamber 70 through the passage 73, the check valve 80 and the passage 72, and is sucked into the pump chamber 60 via the passage 63 of the inner pump rod 62. After that, when the piston rod 14 contracts, the pressure in the pump chamber 60 increases, and when the pressure reaches the pressure set in the check valve 82, the check valve 82 opens but the check valve 80 closes. As a result, the liquid in the pump chamber 60 reaches the intermediate chamber 70 from the passage 63, is supplied to the second reservoir chamber 32 via the passage 74, the check valve 82 and the passage 75, and further via the pipe 76 and the hole 77. . By repeating the above operation, the amount of liquid in the first reservoir chamber 30 and the upper liquid chamber 18 gradually decreases, and the vehicle height decreases.

When the vehicle height is equal to or lower than the predetermined vehicle height, the first pump means 34 and the second pump means 36 operate. The operation of the first pump means 34 at this time is as described above, and the liquid is supplied from the first reservoir chamber 30 to the second reservoir chamber 32. On the other hand, when the piston rod 14 extends, the pump chamber 90 of the second pump means 36 has a negative pressure, and the fourth check valve 104 opens, but the third check valve 10 does not open.
2 is closed. As a result, the liquid in the second reservoir chamber 32 reaches the second intermediate chamber 96 through the hole 77, the pipe 76, the passage 75, the check valve 104 and the passage 100, and passes through the passage 94 and the control hole 110 to the pump chamber. It is sucked into 90. Thereafter, when the piston rod 14 contracts, the pressure in the pump chamber 90 increases, and when the pressure reaches the pressure set in the check valve 102, the check valve 102 opens but the check valve 104 closes. As a result, the liquid in the pump chamber 90 reaches the second intermediate chamber 96 from the control hole 110 and the passage 94, and is supplied to the first reservoir chamber 30 via the passage 98, the check valve 102 and the passage 73. That is, when the vehicle height is equal to or lower than the predetermined vehicle height, the liquid is moved from the first reservoir chamber 30 to the second reservoir chamber 3 by the first pump means 34.
2 and at the same time liquid is transferred from the second reservoir chamber 32 to the first reservoir chamber 30 by the second pump means 36.
Pump chamber 90 of the second pump means 36.
Is larger than the capacity of the pump chamber 60 of the first pump means 34, the above operation is repeated, so that the liquid amounts of the first reservoir chamber 30 and the upper liquid chamber 18 gradually increase,
Vehicle height goes up.

If all valves are arranged on the valve support member 40 as in the illustrated embodiment, the piston rod 14
The structure of the inner pump rod 62 and the outer pump rod 92 can be simplified.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing a main part of an embodiment of a self-pumping type shock absorber according to the present invention.

2 is a cross-sectional view of the self-pumping shock absorber shown in FIG.

[Explanation of symbols]

 10, 38 cylinder 12 piston 14 piston rod 18, 20 liquid chamber 22, 24 damping force generating mechanism 28 hollow hole 30, 32 reservoir chamber 34, 36 pump means 60, 90 pump chamber 62 inner pump rod 92 outer pump rod 110 control hole 114 sleeve

Claims (1)

[Claims] 1. A cylinder, a piston having a damping force generating mechanism which is slidably disposed in the cylinder and partitions the inside of the cylinder into an upper liquid chamber and a lower liquid chamber, and the piston at one end thereof. A self-pumping shock absorber that has a piston rod that is coupled to the other end and that projects from the cylinder to the outside, and that performs a pump function by the expansion and contraction of the piston rod to adjust the vehicle height.
A first reservoir chamber provided outside the cylinder and communicating with the upper liquid chamber, a second reservoir chamber provided outside the cylinder, and the first reservoir chamber to the second reservoir chamber. A first pump means having a first pump chamber for supplying a liquid to the first reservoir chamber, and a liquid which is operated when the vehicle height is equal to or lower than a predetermined vehicle height to supply the liquid from the second reservoir chamber to the first reservoir chamber. A second pump means having a second pump chamber having a larger capacity than the first pump chamber, and a self-pumping shock absorber.