JPH05172101A - Accumulator - Google Patents

Abstract

PURPOSE:To absorb pulsation in high frequency and pulsation in low frequency by partition wall members having respective individual spring constants to reduce noise and vibration of a pump. CONSTITUTION:An accumulator 31 is roughly constituted of a closed vessel 32, a metallic bellows 33 dividing the inside of the closed vessel 32 into a first gas chamber G1 and a first oil chamber Y1, a large diameter holding tube 34 and an attaching tube 36 positioned inside of the first oil chamber Y1, and a metallic bellows 37 provided inside the attaching tube 36 and dividing it into a second gas chamber G2 smaller than the first gas chamber G1 and a second oil chamber. Moreover, as volume of respective gas chambers G1, G2 is set in relationship of G1>G2, high frequency pulsation of small amplitude is absorbed by the metallic bellows 37 of a large spring constant, and low frequency pulsation of a large amplitude is absorbed by the metallic bellows 33 of a small spring constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accumulator suitable for use in hydraulic circuits such as active suspensions.

[0002]

2. Description of the Related Art FIG. 3 shows a vehicle height adjusting hydraulic circuit according to the prior art.

In the drawing, reference numeral 1 denotes a hydraulic pump driven by an engine 2. The hydraulic pump 1 sucks hydraulic oil in a tank 3 through a filter 4, and in the middle of the operation, a pulsation damping accumulator 6 and a check valve. 7, the working oil is supplied as pressure oil into the supply line 5 provided with the main accumulator 8 and the control valve 9.

Reference numeral 6 denotes a pulsation damping accumulator provided in the middle of the supply line 5. Inside the pulsation damping accumulator 6 is an intermediate partition member 6A, and an upper gas chamber 6B and a lower oil storage chamber 6C are provided. The pulsation from the hydraulic pump 1 is damped by the pressure in the gas chamber 6B.

Reference numeral 7 denotes a check valve provided in the middle of the supply line 5. The check valve 7 allows pressure oil from the hydraulic pump 1 to flow toward a tube 17 described later, and is in the reverse direction. To stop the flow of.

8 is located downstream of the check valve 7,
The main accumulator provided in the middle of the supply pipeline 5 is shown, and the inside of the main accumulator 8 is an intermediate partition member 8.
By A, it is divided into an upper gas chamber 8B and a lower oil storage chamber 8C. The main accumulator 8 temporarily stores the pressure oil from the hydraulic pump 1 in the oil storage chamber 8C,
When the vehicle is mounted, this pressure oil will be supplied.

Reference numeral 9 denotes a control valve arranged between the supply pipe line 5 and the supply / discharge pipe 10. The control valve 9 is constituted by a 3-port 3-position proportional control valve, and is normally in the neutral position (a). ), And is switched from the neutral position (a) to the switching positions (b) and (c) by energization from the outside. Then, the control valve 9
Is switched to the switching position (b), the pressure oil from the hydraulic pump 1 is supplied to the hydraulic cylinder 16 described later through the supply pipe line 5, and when switched to the switching position (c), The pressure oil is discharged from the supply / discharge pipe 10 into the tank 3 through the return pipe 11.

Reference numeral 12 denotes an unload valve provided between the return pipe 11 and a connection point 13 between the pulsation damping accumulator 6 and the check valve 7 arranged in the supply line 5. The load valve 12 is composed of a two-port, two-position electromagnetic directional control valve, and is normally placed in a valve opening position (a) for unloading the hydraulic pump 1 by demagnetizing a solenoid portion 12A, which will be described later. The pressure oil from the hydraulic pump 1 is returned to the tank 3 via the return pipe 11. In addition, the unload valve 12 is a control device 14
When the solenoid section 12A is excited by the signal from, the valve opening position (a) is switched to the valve closing position (b),
The pressure oil discharged from the hydraulic pump 1 in order to load-operate the hydraulic pump 1 is supplied to the main accumulator 8 and the control valve 9 side via the supply pipeline 5 and the check valve 7.

Reference numeral 14 denotes a control device, and an input side of the control device 14 is a pressure sensor 15 for detecting the pressure of the pressure oil stored in the oil storage chamber 8C of the main accumulator 8, a vehicle height sensor (not shown), and a steering wheel. It is connected to various sensors such as an angle sensor, and the output side has a solenoid portion 12 of the unload valve 12.
A is connected to each solenoid of the control valve 9.
In the control device 14, the pressure sensor 15 detects the pressure in the oil storage chamber 8C, that is, the pressure on the downstream side of the check valve 7, and the solenoid 12A is excited until the pressure reaches a predetermined pressure. , The unload valve 12 is switched to the closed position (b). On the other hand, when the pressure sensor 15 detects that the predetermined pressure is exceeded, energization to the solenoid portion 12A is stopped and the unload valve 12 is opened to the open position (a).
Switch to. By repeating this, check valve 7
The pressure on the downstream side is maintained at a substantially constant predetermined pressure.

Reference numeral 16 denotes a hydraulic cylinder (only one is shown) as an on-vehicle hydraulic cylinder which is provided on the front and rear wheels of the vehicle and constitutes a suspension system for the vehicle. The hydraulic cylinder 16 has a bottomed cylinder. Tube 17 and the tube 1
A piston (not shown) which is slidably inserted into the inside of the tube and defines the inside of the tube into two upper and lower oil chambers;
The lower end of the piston rod 18 is fixed to the piston and the upper end of the piston rod 18 protrudes upward from the tube 17. The piston rod 18 has the tip connected to the supply / discharge pipe 10. The pressure oil from the supply / discharge pipe 10 is supplied / discharged to / from the oil chamber in the tube 17 and is supplied / discharged to / from a gas spring accumulator 20 provided on the piston rod 18 side via a damping force generating mechanism 19. The accumulator 20 is divided into an upper oil storage chamber 20B and a lower gas chamber 20C by an intermediate free piston 20A.

Reference numeral 21 denotes a drain pipe connected to the outer circumference of the hydraulic cylinder 16, and the drain pipe 21 connects a drain chamber (not shown) of the hydraulic cylinder 16 and the return pipe 11. ..

In the prior art thus constructed, for example, the lower end of the tube 17 is attached to the axle side of the vehicle, and the protruding end side of the piston rod 18 is attached to the vehicle body side. Buffer with 19. In this case, when the piston rod 18 expands and contracts from the tube 17 due to the vibration, the accumulator 20 causes the pressure oil in the oil storage chamber 20B to move to the oil in the hydraulic cylinder 16 via the damping force generating mechanism 19 due to the gas pressure in the gas chamber 20C. When the pressure oil flows into and out of the chamber and the pressure oil flows through the damping force generating mechanism 19, a damping force for vibration damping is generated by the throttling action.

When the vehicle height becomes low due to an increase in the weight of the vehicle, the control valve 9 is switched from the neutral position (a) to the switching position (b) so that the hydraulic pump 1
It is possible to adjust the height of the vehicle by increasing the height of the vehicle by supplying the pressure oil from the oil supply chamber 5 to the oil chamber in the hydraulic cylinder 16 and the oil storage chamber 20B of the accumulator 20 via the supply pipe 5. it can. On the other hand, when the vehicle height becomes high due to the reduction of the loaded weight or the like, the control valve 9 is switched to the switching position (C) so that the pressure oil in the oil chamber and the oil storage chamber 20B of the accumulator 20 is supplied to and discharged from the pipe 10. It can be discharged into the tank 3 through the return pipe 11 and the piston rod 18 can be reduced to adjust the vehicle height to be low.

Further, when the engine 2 is started, the unload valve 12 is set to the open position (a) so that the pressure in the supply pipeline 5 is low, and the unload operation is performed to reduce the load on the engine 2. To be When the engine 2 starts to rotate normally, the unload valve 12
The solenoid portion 12A is energized to switch from the valve opening position (a) to the valve closing position (b) so that the pressure oil from the hydraulic pump 1 is circulated toward the supply pipe line 5 on the downstream side of the check valve 7, and this supply is performed. The pressure in the pipe 5 (pressure on the downstream side of the check valve 7) is set to a predetermined pressure.

In this case, the pressure in the supply line 5 downstream of the check valve 7 is detected by the pressure sensor 15 provided on the oil storage chamber 8C side of the main accumulator 8 and whether or not this pressure has reached a predetermined pressure. Whether the control device 14 determines whether or not a predetermined pressure is reached, the energization of the solenoid 12A is stopped,
By switching the unload valve 12 to the valve opening position (a) and unloading the hydraulic pump 1, the hydraulic pump 1
The load on the engine 2 is reduced to improve the fuel efficiency of the engine 2.

[0016]

By the way, in the above-mentioned prior art, by providing the pulsation damping accumulator 6 in the middle of the supply pipe line 5, the pulsation of the pressure oil discharged from the hydraulic pump 1 is suppressed. ing. But,
The pulsation of pressure oil (hereinafter referred to as “pump pulsation”) is a combination of a high frequency with a small amplitude and a low frequency with a large amplitude, regardless of whether the hydraulic pump 1 is unloading or loading, and therefore the pulsation damping accumulator 6 The frequency region to be reduced is determined by the volume of the gas chamber 6B.

That is, when the volume of the gas chamber 6B is reduced, the pulsation of high frequency with small amplitude can be reduced, but the pulsation of low frequency with large amplitude cannot be reduced. On the other hand, when the volume of the gas chamber 6B is increased, Although the low frequency with large amplitude can be reduced, the pulsation of high frequency with small amplitude cannot be reduced, and there is a problem that the vibration of pulsation cannot be effectively suppressed. Then, there is a problem that pump noise and vibration occur.

The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention can effectively suppress high-frequency and low-frequency pulsations from a hydraulic pump, and reduce pump noise and vibration. The purpose of the present invention is to provide an accumulator that can be used.

[0019]

In order to solve the above-mentioned problems, an accumulator adopted by the present invention comprises a closed container having an oil passage formed on one side, and a displaceable member provided in the closed container. A first partition member defining a first oil chamber and a first gas chamber in the closed container; and a first partition member located in the first oil chamber and displaceably provided in the closed container. A second oil chamber and a second gas chamber defining a second gas chamber in the first oil chamber, wherein the second partition member is formed by a cylindrical metal bellows; The gas chamber is formed with a small capacity so as to absorb the pulsation having a higher frequency than the first gas chamber.

[0020]

With the above structure, the first partition wall member having a small spring constant set by the first gas chamber is actuated to generate a pulsation of a high frequency against a pulsation of a low frequency generated during the operation of the hydraulic pump. On the other hand, the second partition member having a large spring constant set by the second gas chamber operates to suppress the pulsation of the pressure oil discharged from the hydraulic pump.

[0021]

Embodiments of the present invention will be described below with reference to FIGS. In the embodiment, the same components as those in the conventional technique shown in FIG. 4 described above are designated by the same reference numerals, and the description thereof will be omitted.

First, a first embodiment of the present invention will be described with reference to FIG.

In the figure, 31 indicates the accumulator of this embodiment, which is used in place of the accumulator 6 described in the prior art, is located between the hydraulic pump 1 and the check valve 7, and has a supply pipe. It is provided in the middle of the road 5.

Reference numeral 32 denotes a closed container which constitutes the main body of the accumulator 31, and the closed container 32 has a tubular portion 32A, a lid portion 32B for covering the upper end of the tubular portion 32A, and the lid portion 32.
A cylindrical connecting portion 32E protruding from the central portion of B and having an oil passage 32C on the inner peripheral side and a through hole 32D formed in the lid portion 32B, and a bottom portion 32 for covering the lower end side of the tubular portion 32A.
F, a gas charging port 32G formed in the center of the bottom portion 32F and having an internal thread portion formed on the inner peripheral surface thereof, and the lid portion 32B.
, And a plurality of oil passage holes 32H, 32H, ... (Only two shown) for communicating the oil passage 32C with an oil passage 41 described later.

The reference numeral 33 designates a first partition wall provided in the cylindrical portion 32A of the closed container 32 so as to be displaceable in the axial direction, and defining the inside of the closed container 32 into a first gas chamber G1 and a first oil chamber Y1. A first metal bellows as a member is shown. The metal bellows 33 has a bellows-shaped cylindrical portion 33A whose upper end side is fixed to the outer peripheral side of the lower surface of the lid portion 32B by an appropriate fixing means, and a lower end of the cylindrical portion 33A. It is composed of a bottom portion 33B whose side is closed.

Reference numeral 34 denotes a bottomed cylindrical large-diameter holding cylinder provided inside the first oil chamber Y1 defined by the metal bellows 33. The large-diameter holding cylinder 34 has the upper end side as described above. It is located on the lower surface of the lid portion 32B between the inner peripheral side on the upper end side of the metal bellows 33 and the outer peripheral side of each oil passage hole 32H, and is fixed by appropriate fixing means, and extends downward from the lid portion 32B. And a bottom portion 3 for covering the lower end side of the tubular portion 34A
4B, and the large-diameter oil hole 3 is provided at the center of the bottom portion 34B.
4C is drilled. The large-diameter holding cylinder 34 prevents the metal bellows 33 from collapsing or collapsing.

Reference numeral 35 denotes an annular seal member located on the lower surface of the bottom portion 34B of the large diameter holding cylinder 34 and attached to the outer peripheral side of the large diameter oil hole 34C. The seal member 35 is the outermost portion of the metal bellows 33. When the metal bellows 33 comes into contact with the lid portion 32B at the time of contraction, the valve is closed to prevent the flow of pressure oil between the oil passage 41 and the first oil chamber Y1.

Reference numeral 36 denotes a mounting cylinder as a cylindrical mounting portion provided inside the large-diameter holding cylinder 34, and the mounting cylinder 36 is formed slightly shorter than the cylindrical portion 34A of the large-diameter holding cylinder 34. And a lid portion 36B for covering the tubular portion 36A.
And a gas filling port 36 formed in the center of the lid 36B.
C, a bottom portion 36D that covers the cylinder portion 36A, and abuts on the upper surface side of the bottom portion 34B so as to close the large diameter oil hole 34C formed in the bottom portion 34B of the large diameter holding cylinder 34; A small-diameter oil hole 36E is formed in the central portion of 36D, and a lid portion 36B of the mounting cylinder 36 has an appropriate fixing means on the lower surface of the lid portion 32B so as to close the through hole 32D of the closed container 32. It is fixed by. Also, the bottom portion 36
A plurality of cut portions 36F, 36F, ... (Only two are shown) are formed between the outer peripheral side of D and the bottom portion 34D of the large diameter holding cylinder 34, and each cut portion 36F forms an oil passage 41.
Pressure oil is communicated with the oil chambers Y1 and Y2.

37 is provided in the mounting cylinder 36, and inside the mounting cylinder 36 is a second gas chamber G2 and a second oil chamber Y.
2 shows a second metal bellows as a second partition member defined by 2 and the lower end side of the metal bellows 37 is the mounting cylinder 3
The bottom portion 36D of FIG. 6 includes a bellows-shaped tubular portion 37A fixed to the outer circumferential side of the upper surface by means such as welding around the entire circumference, and a lid portion 37B that closes the upper end side of the tubular portion 37A.

Reference numeral 38 denotes an elastic member attached to the central portion of the lid portion 37B of the metal bellows 37, and the elastic member 38 contacts the lower surface of the lid portion 36B of the mounting cylinder 36 when the metal bellows 37 is expanded most.

Reference numeral 39 denotes a small-diameter holding cylinder provided inside the metal bellows 37. The lower end side of the small-diameter holding cylinder 39 is located on the upper surface of the bottom 36D of the mounting cylinder 36 and on the inner peripheral side of the metal bellows 37. Then, the tubular portion 39A fixed by an appropriate fixing means and a lid portion 39C having an oil port 39B for covering the upper end side of the tubular portion 39A are provided. Prevents collapse and collapse.

Reference numeral 40 denotes an annular elastic member attached to the outer peripheral side of the upper surface of the lid portion 39C of the small diameter holding cylinder 39. The elastic member 40 contacts the lid portion 37B when the metal bellows 37 is contracted, and the metal bellows. This is to regulate the time of 37 being the most reduced.

Reference numeral 41 denotes the mounting cylinder 36 and the large-diameter holding cylinder 3.
4 shows an annular oil passage formed between the oil passage 4 and
Reference numeral 1 communicates the pressure oil flowing through the oil passage port 32C and the oil passage hole 32H with the first oil chamber Y1 through the respective cut portions 36F and the large diameter oil hole 34C, and the small diameter oil hole 36E and the small diameter oil hole 36E. It is communicated with the second oil chamber Y2 through the oil port 39B of the holding cylinder 39.

Reference numerals 42 and 43 denote sealing plugs, and the respective sealing plugs 4
Reference numerals 2 and 43 denote O (not shown) in the gas inlet ports 32G and 36C, respectively, after the gas is enclosed in the gas chambers Y1 and Y2.
The gas leakage is prevented by screwing through the ring.

Here, looking at the relationship between the volumes of the gas chambers G1 and G2, the first gas chamber G1 is the second gas chamber G2.
It has become larger than. That is, the first gas chamber G1 is formed so as to have a large volume by covering the cylindrical portion 32A and the bottom portion 32F of the closed container 32, and the second gas chamber G1.
2 is formed so as to have a small volume by being hung on the cylindrical portion 36A and the lid portion 36B of the mounting cylinder 36.

Therefore, the accumulator 3 according to the present embodiment.
1, the metal bellows 33, 3 are manufactured at the time of manufacture.
Gas chambers G1 and G2 defined by 7 are filled with high-pressure gas having substantially the same pressure. The oil chambers Y1 and Y2 defined by the metal bellows 33 and 37 are provided on the upstream side of the check valve 7 through the cut portion 36F, the oil passage 41, the oil passage hole 32H, and the oil passage port 32C. 5, the hydraulic oil from the hydraulic pump 1 acts on the metal bellows 33, 37.

From the relationship of the volumes of the gas chambers G1 and G2, the spring constant acting on the metal bellows 33 becomes small and the spring constant acting on the metal bellows 37 becomes large. Accordingly, of the pump pulsations from the hydraulic pump 1, the pulsations of high frequency with small amplitude can be absorbed by operating the metal bellows 37 with large spring constant, and the pulsations of low frequency with large amplitude can be absorbed. , Can be absorbed by operating the metal bellows 33 having a small spring constant. Therefore, the pump pulsation of the hydraulic pump 1 can be reliably absorbed, and the generation of pump noise and vibration can be effectively prevented.

Furthermore, since the accumulator 31 can be constructed as an accumulator having two gas chambers G1 and G2 in a single closed container 32, it is effective in terms of mounting space and manufacturing, and has different spring constants. Compared with the case where two accumulators are provided, the cost can be significantly reduced.

Next, FIG. 2 shows a second embodiment of the present invention. The feature of this embodiment is that a metal bellows having a large volume is added to a metal bellows having a large volume and a metal bellow having a small volume. The purpose is to provide a seal member that simultaneously seals the passages for pressure oil in both the bellows. In this embodiment, the same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, 51 indicates the accumulator of this embodiment, which is the closed container 32 described in the first embodiment, and the inside of the closed container 32 is the first gas chamber G1 and the first oil. A metal bellows 33 as a first partition member that is defined in the chamber Y1, a large-diameter holding cylinder 34 and a mounting cylinder 36 that are provided in the first oil chamber Y1, and the mounting cylinder 3
Although it is generally constituted by a metal bellows 37 provided in the second gas chamber G2 and defining a second oil chamber G2 and a second oil chamber, and a small diameter holding cylinder 39 for preventing the metal bellows 37 from collapsing, The operation start pressure of the metal bellows 33 having a large volume is set to be higher than the operation start pressure of the metal bellows 37 having a small volume, and the metal bellows 33 is
At the central portion of the bottom portion 33B, a sealing member 52 formed of a rubber material in the form of a stepped column is attached to the upper side.

Here, the seal member 52 has a protrusion seal portion 52A which closes the small diameter oil hole 36E when the metal bellows 33 is reduced to the minimum size, and a disk-shaped seal which closes the large diameter oil hole 34C of the large diameter holding cylinder 34. And the surface 52B.

The accumulator 51 according to the present embodiment can also obtain the same effect as the first embodiment described above, but in this embodiment, the elastic member is reduced as compared with the first embodiment. In addition, the oil passage 41 and the oil chambers Y1,
Each of the oil holes 34C and 36E communicating with Y2 is connected to the seal member 5
It can be closed only by 2, and the cost can be reduced.

In each of the above embodiments, the low-frequency pump pulsation having a large amplitude is absorbed by the operation of the metal bellows 33 which defines the gas chamber G1 having a large volume, but the present invention is not limited to this. Alternatively, the partition member that absorbs low-frequency pump pulsation may be formed by a free piston. Further, if the gas pressures of the gas chambers G1 and G2 are made different, an accumulator corresponding to a wide range of pump pressures can be constructed.

In each of the above embodiments, the unload valve 1
The case where 2 is provided outside the hydraulic pump 1 has been described as an example, but the present invention is not limited to this, and the unload valve 12 may be connected between the projecting port of the hydraulic pump 1 and the tank 3. In this case, the supply line 5 may be configured to include the discharge port of the hydraulic pump 1. Further, the hydraulic circuit is not limited to the one using the unload valve 12, and, for example, the unload valve 12 may be replaced with a hydraulic circuit using a means such as a relief valve for keeping the hydraulic circuit pressure constant.

Furthermore, in each of the above-mentioned embodiments, the case where the accumulator is used in the hydraulic circuit for adjusting the vehicle height has been described as an example, but the present invention is not limited to this, and the hydraulic circuit for power steering and the anti-skid brake are used. It can be easily used in a hydraulic circuit for a system.

[0046]

As described in detail above, according to the present invention, the accumulator is provided in a closed container having an oil passage formed in one side thereof, and is displaceably provided in the closed container. A first partition wall member that defines a first oil chamber and a first gas chamber; and a first partition member that is located in the first oil chamber and is displaceable in the closed container; A second partition member that defines a second oil chamber and a second gas chamber, the second partition member being formed of a tubular metal bellows,
Since the second gas chamber is formed with a small capacity to absorb the pulsation of a higher frequency than the first gas chamber, among the pulsations of the pressure oil that acts on each oil chamber in the closed container from the oil passage, The first partition member having a small spring constant, which is set by the first gas chamber, operates for the pulsation with a large amplitude and the low frequency, and the second gas has a small pulsation for the high frequency with a small amplitude. A second partition member with a large spring constant set by the chamber is activated. Then, the pulsation of the pressure oil can be effectively damped, and pump noise, vibration, etc. can be reliably reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an accumulator according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional view showing an accumulator according to a second embodiment.

FIG. 3 is a circuit diagram showing a vehicle height adjusting hydraulic circuit according to a conventional technique.

[Explanation of symbols]

 1 Hydraulic Pump 31, 51 Accumulator 32 Airtight Container 33 Metal Bellows (First Partition Member) 36 Mounting Cylinder (Mounting Part) 37 Metal Bellows (Second Partition Member) G1 First Gas Chamber G2 Second Gas Chamber Y1 First oil chamber Y2 Second oil chamber

Claims (1)

[Claims] 1. A closed container having an oil passage formed on one side,
A first partition member provided displaceably in the closed container and defining a first oil chamber and a first gas chamber in the closed container; and a first partition member located in the first oil chamber, A second oil chamber and a second oil chamber are provided so as to be displaceable in the closed container, and are provided in the first oil chamber.
And a second partition member that defines a gas chamber of the second gas chamber, and the second partition member is formed of a cylindrical metal bellows, and the second gas chamber has a higher frequency than the first gas chamber. An accumulator formed with a small capacity to absorb pulsation.