JPH0460226A - Hydraulic buffer - Google Patents

Abstract

PURPOSE:To absorb an impact so effectively as well as to improve the extent of safety by interrupting an interval between two oil chambers with a pressure valve at the initial stage of a collision, and when pressure in the oil chamber exceeds a specified level, securing a sufficient stroke quantity as the pressure valve is opened. CONSTITUTION:A pressure valve 24 is installed in a piston 21 via a holder 22, and its valve element 25 is normally energized in the valve closing direction by dint of a valve spring 26. At the initial stage of absorbing impact energy through an impact absorbing material, in case of a car crash, the valve element 25 interrupts an interval between two oil chambers B and C, thereby checking such a possibility that an inner cylinder 5 might be stroked in the X direction. In addition, when pressure in the oil chamber C exceeds the specified one due to impact force, the valve element 25 is slidden toward the side of the oil chamber B against the valve spring 26, and oil in the oil chamber C flows into the oil chamber B via an oil passage. This oil produces large damping force when it flows through each orifice hole 25D, through which the inner cylinder 5 is stroked in the X direction as absorbing the extent of impact energy so effectively.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a hydraulic shock absorber that is installed, for example, at the front of a vehicle and is suitably used to dampen shocks in the event of a collision. , relates to a hydraulic shock absorber that is used in combination with a shock absorbing material made of a resin material or the like.

[Prior Art] FIG. 4 shows an example of a vehicle bumper shock absorber as a conventional hydraulic shock absorber.

In the figure, reference numeral 1 denotes an outer cylinder constituting the main body of a bumper shock absorber. The outer cylinder 1 is formed in a cylindrical shape, and one end of the outer cylinder 1 is closed by a substantially disc-shaped lid 2. In addition, the outer cylinder 1
A mounting bracket 3 is fixed to the outer periphery of the other end, and the mounting bracket 3 is adapted to mount the outer cylinder 1 to the vehicle body side of the vehicle. Reference numeral 4 indicates a locking projection as a stopper formed by bending the other end of the outer cylinder 1 in the radial direction. It is designed to prevent it from coming off.

5 is an inner cylinder that is slidably inserted into the outer cylinder 1 at one end and protrudes outside the outer cylinder 1 at the other end, and is located at the middle part in the length direction on the outer peripheral side of the inner cylinder 5. A stopper part 5A that regulates the full stroke position of the inner cylinder 5, and a stepped part 5B that is located between the stopper part 5A and one end of the inner cylinder 5 and that allows the inner cylinder 5 to slide within the outer cylinder 1. It projects outward in the radial direction. Also,
A mounting plate 6 on the bumper side is fixed to the protruding end of the inner cylinder 5 by means such as welding, and a plug 7 is attached to the mounting plate 6 to fill the gas chamber A with pressurized gas, which will be described later. It is fixed to seal chamber A.

Reference numeral 8 denotes a free piston slidably inserted into the inner cylinder 5, and the free piston 8 defines the inside of the inner cylinder 5 into a gas chamber A on the projecting end side and an oil chamber B on the one end side, The gas chamber A and oil chamber B
It is designed to slide within the inner cylinder 5 when a pressure difference occurs between the two.

Reference numeral 9 indicates a piston as a partition wall that is fitted and fixed to one end side of the inner cylinder 5 and slidably inserted into the outer cylinder 1. The piston 9 is connected to the inner cylinder 5 defined by the free piston 8. Oil chambers B and C are defined at one end side and inside the outer cylinder 1, respectively, and an annular oil chamber is defined between the outer cylinder 1 and the inner cylinder 5 and located between the step portion 5B. has been completed. Reference numeral 10 denotes an oil chamber bored in the center of the piston 9. The oil chamber 10 communicates between the oil chambers B and C, and the other end of a metering bottle 11, which will be described later, is inserted into the oil chamber 10.

Reference numeral 11 indicates a metering bottle that extends in the axial direction within the oil chamber C and has one end fixed to the center of the lid 2, and the diameter of the metering bottle 11 gradually decreases from one end to the other end. It is formed into a tapered shape, and the other end side is the oil chamber 1 of the piston 9.
It is inserted within 0. And the metering bin 1
1 forms an orifice passage 12 in the oil chamber 10, and the orifice passage 12 allows oil to flow from the oil chamber C to the oil chamber B when the piston 9 slides toward the oil chamber C side. A squeezing action is applied to the liquid, and the damping force generated at this time gradually increases in accordance with the outer diameter of the metering bottle 11.

In the bumper shock absorber configured as described above, when an impact force is applied in the direction of the arrow X due to a vehicle collision, etc., the inner cylinder 5 is pressed into the outer cylinder 1 together with the piston 9 in the direction of the arrow X. Ru. When the pressure in the oil chambers B and C becomes higher than the pressure in the gas chamber A, the free piston 8 slides toward the gas chamber A side due to this pressure difference, and the inner cylinder 5 and the piston 9 move toward the oil chamber C. The pressure oil in the oil chamber C flows into the oil chamber B through the orifice passage 12.

Here, the orifice passage 12 is connected to the metering bin 11.
Because of this, its effective cross-sectional area is small (and it exerts a throttling effect on the flowing pressure oil), so the pressure oil flowing through the orifice passage 12 can generate a damping force and absorb the energy generated at the time of collision. Can buffer shock.

Since the metering bottle 11 has a tapered shape and gradually expands in diameter, when the piston 9 slides toward the oil chamber C side, the generated damping force can be gradually increased, and the impact at the time of a collision can be alleviated. I can do it.

[Problem to be solved by the invention]

By the way, in the above-mentioned conventional technology, since the free piston 8 provided in the inner cylinder 5 has the same pressure receiving area for gas pressure and oil pressure in the gas chamber A and the oil chamber B, the free piston 8 is disposed in the case of a collision. 8 is relatively high (sliding, inner cylinder 5
There is a problem in that it is difficult to use in combination with a shock absorbing material made of an elastic resin material such as urethane, for example, because the shock absorber begins to shrink (stroke) into the outer cylinder 1 at an early stage.

That is, when the impact energy is being absorbed by the cushioning material at the beginning of the impact, the free piston 8 may slide early and the inner cylinder 5 may begin to contract, and when the cushioning material has finished absorbing the energy, The inner cylinder 5 makes a large stroke into the outer cylinder 1, and the subsequent stroke amount becomes small, making it impossible to obtain an effective buffering effect.

The present invention has been made in view of the problems of the prior art described above. Even when used in combination with a shock absorbing material, the present invention can obtain an effective buffering effect, absorbing the impact at the time of a collision, and improving safety. The purpose of the present invention is to provide a hydraulic shock absorber that can be improved.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides an outer cylinder, an inner cylinder whose one end side is inserted into the outer cylinder, and whose other end side projects outside the outer cylinder, and which is slidable on the inner cylinder or the outer cylinder. a free piston that is inserted into the inner cylinder or the outer cylinder and defines a gas chamber and an oil chamber; and a partition wall that is provided in the inner cylinder or the outer cylinder and defines two oil chambers that are defined by the free piston. an oil passage communicating between the oil chambers defined by the partition wall; and an oil passage provided in the middle of the oil passage, which is normally closed to block the oil passage;
a pressure valve that opens when pressure in an oil chamber located on the opposite side of the free piston among the oil chambers exceeds a predetermined high pressure, and allows communication between the oil chambers through the oil passage; A configuration consisting of is adopted.

[Effect]

With the above configuration, for example, when used together with a shock absorbing material,
At the initial stage when the cushioning material absorbs the collision energy, the oil passage between each oil chamber can be blocked by a pressure valve to prevent the flow of oil and prevent the inner cylinder from stroking into the outer cylinder. can. Then, when the pressure in the oil chamber located on the opposite side of the free piston exceeds a predetermined high pressure level, the pressure valve opens, allowing the oil passage to communicate with each other and allowing for a smooth stroke, ensuring a sufficient stroke amount. can.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3. In this embodiment, the same components as those of the prior art shown in FIG. 4 described above are given the same reference numerals, and their explanations will be omitted.

FIG. 1 shows a first embodiment of the present invention.

In the figure, 21 indicates a piston as a partition wall that is fitted and fixed to one end side of the inner cylinder 5 and slidably inserted into the outer cylinder 1, and the piston 21 is different from the piston 9 described in the prior art. Although oil chambers B, C, and D are defined in the outer cylinder 1 and the inner cylinder 5 in almost the same way, a circular sliding hole 21A is bored in the center of the piston 21 in the axial direction. . An annular protrusion 21B surrounding the sliding hole 21A is provided on the end surface of the piston 21 on the oil chamber B side. Oil groove 21
C (only one is shown) is formed. The piston 21 also has an annular protrusion 21B located on the end face on the oil chamber C side.
A ring-shaped groove 21D extending in the circumferential direction and having a larger radial dimension than It is opened and closed by a disc valve 27, which will be described later.

Reference numeral 22 indicates a holder located in the oil chamber B and fixed between the inner cylinder 5 and the piston 21. The holder 22 is formed in a stepped cylindrical shape, and is connected to a large diameter portion 25A of the valve body 25, which will be described later. It is designed to be slidably held. Moreover, the holder 22
A flange portion 22A that protrudes radially outward and is held between the end surface of the inner cylinder 5 and the piston 21 is bored at one end side, and a plurality of oil chambers 22B are provided in the middle of the flange portion 22A.
, 22B, . . . are bored in the axial direction.

An annular spring receiving part 22C is bored radially inward at the other end of the holder 22, and the spring receiving part 22C connects one end of a valve spring 26, which will be described later, through an annular shim plate 23. It is designed to be retained.

Reference numeral 24 indicates a pressure valve disposed between the piston 21 and the holder 22, and the pressure valve 24 includes a substantially disk-shaped large diameter portion 25A that is slidably inserted into the holder 22, and a large diameter portion 25A that is slidably inserted into the holder 22. Diameter 2
A valve body 25 consisting of a short cylindrical small diameter valve portion 25B bored in the axial direction from the end face of the valve body 5A, and a large diameter portion 25 of the valve body 25.
A valve spring 26 is disposed between A and the spring receiving portion 22C of the holder 22 via a shim plate 23, and the spring load f is set based on the thickness or number of the shim plates 23. The valve spring 26 constantly biases the valve body 25 in the direction of arrow X. The small diameter valve portion 25B of the valve body 25 is slidably inserted into the sliding hole 21A of the piston 21, and has a bottomed hole 25C in the axial direction that opens at the end surface of the small diameter valve portion 25B, and the bottomed hole 25C. A plurality of orifice holes 25D are provided which extend in the radial direction and open on the outer circumferential surface of the small diameter valve portion 25B so as to constantly communicate with the small diameter valve portion 25C.

Here, the bottomed hole 25C and each orifice hole 25D of the valve body 25 are connected to the sliding hole 21A of the piston 21, and each oil groove 2IC.
Together, they form an oil passage that communicates between the oil chambers B and C, and this oil passage connects the oil chambers B and C between the sliding hole 21A and the oil groove 21C via each orifice hole 25D of the valve body 25. communicate,
It is designed to be blocked. That is, in the valve body 25, the small diameter valve portion 25B has a pressure receiving area S with respect to the pressure of the oil chamber C, and the large diameter portion 25A has a substantially similar pressure receiving area S with respect to the pressure of the oil chamber B. Since the valve body 25 is urged by the valve spring 26 in the direction of the arrow X with a spring load f, the oil chambers B and C
When the inside is dynamic pressure and pressure P, PXS<PXS+f -----... (1),
The valve body 25 is closed as shown in the figure, and the oil chambers 80 are cut off.

Then, when the pressure P in the oil chamber C rises to a predetermined high pressure PC, PcX5=PXS+f -...-(2), and when the pressure in the oil chamber C exceeds the high pressure PC, the valve body 25 slides toward the oil chamber B side against the valve spring 26 to open the valve, and the valve body 2
Each orifice hole 25D of 5 corresponds to each oil groove 21 of the piston 21.
The oil chambers B and C communicate with each other.

Furthermore, 27 opens the ring-shaped groove 21D of the piston 21,
A disc valve as a check valve is provided on the end face of the piston 21 to be closed, and the disc valve 27 is shown as a check valve.
allows the oil in the oil chamber B to flow in one direction into the oil chamber C via the oil filler 21E and the ring-shaped groove 21D, and prevents the oil from flowing in the opposite direction. The disc valve 27 is opened in the oil chamber after the valve body 25 of the pressure valve 24 contacts the annular protrusion 21B of the piston 21 and closes as shown in the figure during assembly of the shock absorber or return after a collision. Transfer the oil in B to oil chamber C.
The free piston 8 causes the gas A in the gas chamber A to flow out into the gas chamber A.
The pressure allows it to slide toward the oil chamber B in the direction of arrow X.

The bumper shock absorber according to this embodiment has the above-mentioned configuration, and its basic operation is not particularly different from that of the prior art.

However, in this embodiment, a pressure valve 24 is provided on the piston 21 via a holder 22, and the pressure valve 24 is composed of a valve body 25 and a valve spring 26. Each orifice hole 25 is inserted into the sliding hole 21A.
Since the structure is such that the oil chambers B and C are communicated and isolated between D and each oil groove 21C, and the valve body 25 is always biased in the valve closing direction with a spring load f by the valve spring 26, for example, urethane When a shock absorber made of an elastic resin material such as ( 2) Predetermined high pressure Pc according to formula, p c = p a + f/ S ・”-(3) However, P8: The valve body 25 of the pressure valve 24 is closed as shown in the figure until the pressure in the oil chamber B is reached. It can be maintained in a valve state, and the oil chambers B and C can be shut off to prevent the inner cylinder 5 from stroking into the outer cylinder 1 in the direction of the arrow X.

The shock absorbing material absorbs the collision energy, and the pressure P in the oil chamber C increases to a high pressure Pc due to the impact force in the direction of the arrow X.
When the valve body 25 exceeds the valve spring 26, the valve element 25 slides toward the oil chamber B side against the valve spring 26, and the sliding hole 21A and the bottomed hole 25
C1 An oil passage consisting of each orifice hole 25D and each oil groove 21G communicates between each orifice hole 25D and each oil groove 2IC, and the oil in the oil chamber C is directed into the oil chamber B via the oil passage. Since this oil fluid flows through each orifice hole 25D, a large damping force can be generated, and the inner cylinder 5 is directed into the outer cylinder 1 while effectively buffering the collision energy. It can be stroked in the X direction.

In addition, when the valve body 25 of the pressure valve 24 opens, the oil chambers B and C communicate with each other, and the pressure difference ΔP between the oil chamber C and the oil chamber B is calculated based on the above equation (3), for example, by the differential pressure value. When the value becomes smaller than f/S, the valve body 25 closes again as shown in the figure and opens the oil chambers B and C.
After that, when the differential pressure becomes larger than f/S, the valve opens and oil chamber B is opened.

6 are communicated with each other, a large damping force can be generated in each orifice hole 25D, and collision energy can be effectively absorbed until the inner cylinder 5 reaches the stroke end.

Therefore, in this embodiment, by closing the valve body 25 of the pressure valve 24 at the initial stage of an impact caused by a vehicle collision, etc., it is possible to reliably prevent the inner cylinder 5 from stroking into the outer cylinder 1. In addition to being able to absorb the collision energy with a shock absorbing material or the like, the valve body 25 is then opened when the pressure inside the oil chamber C exceeds a predetermined high pressure Pc, and the inner cylinder 5 is connected to the outer cylinder. 1, the shock can be effectively absorbed by the shock absorber while the inner cylinder 5 is stroked in the direction of the arrow X, a sufficient stroke amount of the inner cylinder 5 can be secured, and safety in the event of a collision can be greatly improved. It has the effect of

Next, FIG. 2 shows a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and their explanations will be omitted. The feature of this embodiment is that the flange portion 31A is connected to the end surface of the inner cylinder 5 and the piston 21.
The holder 31 which is sandwiched between the inner cylinder 5 and the piston 21 is formed into a bottomed cylindrical shape, and pressurized gas is sealed in the holder 31 via the plug 32. The valve body 34 is always biased in the valve closing direction by this gas pressure.

Here, the valve body 34 of the pressure valve 33 is slidably inserted into the holder 31 and is connected to the bottom of the holder 31 in the gas chamber E.
a large-diameter portion 34A in the form of a covered cylinder defining a large-diameter portion 34A;
The sliding hole 2 of the piston 21 protrudes from the end surface of the piston 21 in the axial direction.
1. , and a small diameter valve part 34B slidably inserted into A, and the small diameter valve part 34B has a bottomed hole 34C and each orifice hole, similar to the valve body 25 described in the first embodiment. 34D is formed. In addition, a plurality of oil chambers 31B are axially bored in the flange portion 31A of the holder 31, and the pressurized gas sealed in the gas chamber E is supplied with the same pressure as the valve spring 26 used in the first embodiment. The valve body 34 is urged in the valve closing direction with the urging force f.

Thus, in this embodiment configured as described above, the pressure valve 33 can be configured by the valve body 34, the gas chamber E, etc., and substantially the same effects as in the first embodiment can be obtained. The biasing force f can be adjusted by changing the amount of pressurized gas sealed in the gas chamber E.

Next, FIG. 3 shows a third embodiment of the present invention, and this embodiment is characterized by the above-mentioned first embodiment. Free piston 8 provided in the inner cylinder 5 in the second embodiment. Gas chamber A, piston (partition wall) 21.
The pressure valve 24 (33) and the like are provided in the outer cylinder, contrary to this. Note that in this embodiment, the first. Second
Components that are the same as those in the embodiment will be denoted by "r'" and their explanation will be omitted.

Here, the outer cylinder 1' is formed into a double structure consisting of an inner cylinder IA' and an outer cylinder IB', and an annular free piston 8' is slidably provided in this outer cylinder 1'.
There is an annular gas chamber A' on the opposite side (outside) from the inner cylinder 5' side of '.
An oil chamber B'C' is defined on the opposite side (inside) of the gas chamber A' of the outer cylinder 1', and a partition wall 21 integral with the mounting bracket 3' is formed on one end side of the outer cylinder 1'. ' and a holder 31' are provided to convert the oil chambers B' and C' into a first oil chamber B' defined between the partition wall 21' and the free piston 8'.
and the partition wall 21', a part of the outer cylinder 1', and the inner cylinder 5'.
A pressure valve 33' similar to that of the second embodiment is provided on the partition wall 21'. And this pressure valve 33'
opens when the pressure in the second oil chamber C' exceeds a predetermined high pressure Pc due to an impact, and the inner cylinder 5' is inserted into the outer cylinder 1'.
It is arranged in the sliding hole 21A' of the partition wall 21' so as to allow the stroke with a predetermined damping force.

(Thus, this embodiment configured in this manner can also obtain substantially the same functions and effects as those of the above-mentioned embodiments.

In addition, in each of the above embodiments, the piston 21 or the partition wall 2
1' is provided with an annular protrusion 21B (21B'), and a valve body 25 (34, 34') is provided on the annular protrusion 21B (21B').
) large diameter portion 24A (34A.

34A"), but instead of this, the large diameter portion 25A (34A") is brought into contact with the end surface.

34A') may be provided with an annular protrusion 21B (21B') and an oil groove similar to each oil groove 21C (21C').

〔Effect of the invention〕

As detailed above, according to the present invention, a pressure valve is provided in the middle of an oil passage communicating between each oil chamber defined by a partition wall,
The pressure valve is closed until the pressure in the oil chamber located on the opposite side of the free piston exceeds a predetermined high pressure, and the oil chambers are shut off, so even when used together with shock absorbing material, this It is possible to suppress the stroke of the inner cylinder into the outer cylinder at the initial stage when the cushioning material absorbs the collision energy, and after that, it is possible to ensure a sufficient stroke amount to effectively buffer the impact, and in the event of a collision. It has various effects, such as greatly improving the safety of

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a bumper shock absorber showing a first embodiment of the present invention, FIG. 2 is a longitudinal sectional view of main parts of a bumper shock absorber showing a second embodiment, and FIG. FIG. 4 is a vertical cross-sectional view of a bumper shock absorber showing a conventional technique. 1.1'...Outer cylinder, 5.5''...Inner cylinder, 8.8'.
...Free piston, 21...Piston (partition wall),
21'...Partition wall, 21A, 2LA'...Sliding hole,
22.31.31'...Holder, 24,33°33'
...Pressure valve, 25, 34.34''...Valve body, 25A
, 34A, 34A'...large diameter portion, 25B. 34B, 34B"...Small diameter valve part, 25C, 34C. 34C'...Bottomed hole, 25D, 34D, 34D'...
・Orifice hole, 26...Valve spring, 27.27'...
・Disc valve, A, A', E, E'...gas chamber, B, B', C, C'...oil chamber.

Claims (1)

[Claims] an outer cylinder, an inner cylinder whose one end side is inserted into the outer cylinder and whose other end side projects outside the outer cylinder; and an inner cylinder which is slidably fitted into the inner cylinder or the outer cylinder, and which connects the gas chamber and the oil chamber. a free piston defining a
a partition wall provided in the inner cylinder or the outer cylinder and defining an oil chamber defined by the free piston into two oil chambers;
An oil passage that communicates between the oil chambers defined by the partition wall, and a valve provided in the middle of the oil passage, which is normally closed to block the oil passage, and which is connected to the free piston of each oil chamber. A hydraulic shock absorber comprising a pressure valve that opens when the pressure in an oil chamber located on the opposite side exceeds a predetermined high pressure to allow communication between the oil chambers through the oil passage.