JPH0485128A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To improve riding comfortableness by connecting main accumulators to the discharge side of a hydraulic pump through a pulsation absorbing accumulator fitted to an engine and a pulsation absorbing hose in a vehicular suspension device for adjusting a suspension characteristic by the supply/discharge of oil to/from a hydraulic cylinder. CONSTITUTION:A pulsation absorbing accumulator 25 is separately provided at a main supply passage 6a on the discharge side of a hydraulic pump 5, and fitted to an engine. A filter 26 is connected to the downstream side of the separation point of this pulsation absorbing accumulator 25, and pressure accumulating main accumulators 21 are connected to front-rear wheel side branch supply passages 6b, 6b on the downstream side of the filter 26. An operating fluid passage part from the pulsation absorbing accumulator 25 of the main supply passage 6a to the main accumulators 21 is formed of a pulsation absorbing hose. With this constitution, vibration preventive fitting structure becomes unnecessary, and thereby the structure is simplified.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is designed to change and adjust suspension characteristics by supplying and discharging oil to a hydraulic cylinder installed between a sprung portion and an unsprung portion of a vehicle. The present invention relates to a suspension device for a vehicle.

[Conventional technology]

For example, in Japanese Patent Application Laid-open No. 63-130418, in order to improve ride comfort by stabilizing the posture of the vehicle body, there is A hydraulic cylinder that can expand and contract according to displacement is installed, and a control valve is interposed in the oil passage from the hydraulic pump to the hydraulic cylinder, and this control valve controls the supply and discharge of oil to each hydraulic cylinder. A so-called active suspension device has been disclosed in which the suspension characteristics can be changed by changing the suspension characteristics.

In this type of suspension device, it is necessary to supply high-pressure oil in order to generate, in each hydraulic cylinder, a reaction force against the load from the wheel side in addition to a supporting force against the vehicle weight. For this reason, a piston pump such as a plunger pump is used as the hydraulic pump, and an accumulator is connected to the oil passage from the hydraulic pump to the control valve to accumulate pressure in the accumulator. It supplies high pressure oil to the hydraulic cylinder.

[Problem to be solved by the invention]

However, as mentioned above, plunger pumps used as high-pressure hydraulic pumps are thick (and have a pulsating discharge pressure characteristic), so pressure fluctuations in response to this pulsation tend to occur in the supply line pressure to the control valve. As a result, the amount of oil supplied to and discharged from the hydraulic cylinder fluctuates, creating the problem that accurate control of suspension characteristics cannot be performed.Furthermore, as mentioned above, pulsating oil is not directly attached to the vehicle body. There is also the problem that as a result of being supplied to the accumulators and control valves, the vehicle body vibrates and noise is generated, impairing ride comfort.

The present invention has been made in view of the above conventional problems, and its purpose is to improve ride comfort by improving the controllability of suspension characteristics and suppressing vibration and noise, and to improve the structure for this purpose. It is an object of the present invention to provide a suspension device for a vehicle that can be made simpler.

[Means to solve the problem]

Therefore, in the vehicle suspension system of the present invention, hydraulic cylinders are provided on the sprung and unsprung parts, and the oil discharged from the hydraulic pump driven by the engine is controlled to be supplied and discharged to the hydraulic cylinders, thereby improving the suspension characteristics. A changeable vehicle suspension device comprising:
A pulsation absorbing accumulator is connected between a pressure accumulating main accumulator connected to the discharge side of the hydraulic pump and attached to the vehicle body and the discharge side of the hydraulic pump, and a pulsation absorbing accumulator is connected to the main accumulator. A pulsation absorbing hose is interposed in the piping leading to the engine, and the pulsation absorbing accumulator is attached to the engine.

[For production]

According to the above configuration, the oil discharged from the hydraulic pump is
The pulsation is absorbed by the pulsation absorbing accumulator and the pulsation absorbing hose and is supplied to the main accumulator. In other words, when the pulsation absorbing accumulator is configured to absorb low frequency pulsations, by using the pulsation absorbing hose to absorb high frequency pulsations, pulsations over almost the entire frequency range can be removed. This makes it possible to supply oil with pressure fluctuations minimized. As a result, it becomes possible to control the suspension characteristics with higher control accuracy, improving the ride comfort, and also suppressing vibrations and noise in the control equipment that receives this pressure oil supply, improving the ride comfort.

Further, the pulsation absorbing accumulator itself generates vibrations due to the inflow of pulsating oil from the hydraulic pump. Therefore, in the above, the pulsation absorbing accumulator is attached to the engine. The engine is installed in such a way that the influence of vibration on the car body is minimized, for example by using rubber mounts, etc., and by installing the above-mentioned pulsation absorbing accumulator to this engine, this pulsation absorbing accumulator is installed. There is no need for a vibration-preventing mounting structure dedicated to the accumulator, and therefore the mounting structure can be made simpler.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

As shown in FIG. 3, the vehicle body 1 constituting the sprung portion is
Four units are arranged on the front and rear wheels 2 and 3 and wheel support members (not shown) such as axles, which constitute the unsprung portion, at locations close to the left and right front and rear wheels 2 and 3, respectively. It is supported via hydraulic cylinders 4... Each hydraulic cylinder 4
each includes a cylinder body 4a coupled to the vehicle body 1 side, and a piston 4b fitted into the cylinder body 4a so as to be reciprocally movable, and a lower end portion of a piston rod 4c extends downward from each piston 4b. is coupled to the wheel support member.

Each of the hydraulic cylinders 4 has an oil passage 6 connected to a hydraulic pump 5.
A control valve 7 for controlling the supply and discharge of oil to each hydraulic cylinder 4 is installed in each branch passage of the oil passage 6 on the side of each hydraulic cylinder 4. . On the other hand, vehicle height sensors 8a to detect the height of the vehicle body 1, acceleration sensors 8b to detect the vertical acceleration of the vehicle body, etc. are arranged at appropriate locations on the vehicle body 1, and each of these sensors 8a - A control unit 9 is provided that controls the operation of each of the control valves 7 based on the detection signal at 8b and the detection signal at the pressure sensor 8C that detects the pressure at a predetermined portion in the oil passage 6. . By operating each control valve 7 in response to a command signal from the control unit 9, the amount of oil supplied to and discharged from each hydraulic cylinder 4 is changed as appropriate, and thereby the suspension characteristics of the vehicle are changed and adjusted. This suppresses the vertical movement of the vehicle body when driving on the road or cornering, and also maintains a nearly constant horizontal posture.

As shown in FIG. 4, the oil passage 6 from the hydraulic pump 5 to each hydraulic cylinder 4 includes a main supply passage 6a connected to the discharge side of the hydraulic pump 5, and a downstream end of the main supply passage 6a. Branched from the front wheel side valve unit 10F
and a front wheel side branch supply path 6b and a rear wheel side branch supply path 6b'' for supplying oil to the rear wheel side valve unit IOR, respectively, and branches branched from the downstream ends of these branch supply paths 6b and 6b'', respectively. Two left and right wheel branch supply paths 6 each
c... is provided. The downstream end of each of these left and right wheel branch supply paths 6c... is connected to each of the control valves 7, .
... is connected to supply boat A.

Each control valve 7 has three boats: the supply boat A), the discharge port B), and a switching boat P that is switched and communicated with the supply boat A and the discharge port 1-B, and each boat A-B. 3 positions: a neutral position that cuts off between B and P, a first switching position that allows communication between supply port A and switching port P, and a second switching position that allows communication between discharge port A) B and switching port P. It consists of a proportional solenoid valve with a

The aforementioned hydraulic cylinders 4 are connected to the switching boats P of each control valve 7 via supply and discharge passages 6d, respectively. On the other hand, a discharge port 6e of each control valve 7 is connected to a discharge port 6e, respectively.
e... are connected to left and right wheel collective discharge passages 6f and 6f provided for each of the front wheel valve unit 10F and the rear wheel valve unit 10R, respectively. These left and right wheel collective discharge passages 6f, 6f are further connected to each other via a front wheel side discharge passage 6g and a rear wheel side discharge passage 6g', and this connection point is connected to the reserve tank 11 by the main discharge passage 6h.
It is connected to the.

The hydraulic pump 5 has a suction side connected to the reserve tank 11 through a suction passage 61, and also has a built-in relief valve 12 connected between the discharge side and the suction side of the hydraulic pump 5. The maximum discharge pressure of this hydraulic pump 5 is regulated by the valve 12 .

Further, an unload relief valve 13 is connected between the main supply path 6a and the main discharge path 6h, and the unload relief valve 13 is configured such that the supply pressure from the hydraulic pump 5 is at an upper limit (for example, 160 kg/c+11 ), the valve opens and the oil discharged from the hydraulic pump 5 is released into the reserve tank 11.
kg/cJ) or less, the valve is controlled to close, thereby keeping the pressure of the oil supplied through the main supply path 6a within a set range.

In addition, each left and right wheel branch supply path 6c..., discharge path 6e...
A pilot type pressure reducing valve 14... is provided in each of the valves. These pressure reducing valves 14... are operated on the upstream side of each pressure reducing valve 14 using the pressure on the supply boat A or discharge port) B side and the pressure on the switching boat P side in each control valve 7 as pilot pressures. and operates to keep the pressure difference on the downstream side constant.

In addition, a normally closed shutoff valve 15 is provided in each supply and discharge passage 6d, and two shutoff valves are provided in each of the front wheel valve unit IOF and the rear wheel valve unit 1oR. Pilot port a'a of valve 15/15
They are mutually connected by a pilot passage 6j. These pyro throat passages 6j and 6j are connected to the pilot supply passage 6 and pilot relief to the front and rear wheel side branch supply passages 6b and 6b' and the left and right wheel collective discharge passages 6f and 6f by means of electromagnetic switching valves 16 and 16, respectively. Communication is switched via path 61. When energizing the electromagnetic switching valve 16,
When the cutoff valve 15 is opened and each supply/discharge passage 6d is opened, while the ignition key switch (not shown) of the vehicle is turned off and each of the electromagnetic switching valves 16 is de-energized, When the oil supply pressure decreases, the shutoff valve 15 closes and each supply/discharge passage 6d is closed, thereby sealing the oil inside each hydraulic cylinder 4.

In addition, between each supply/discharge passage 6d and the left and right wheel collective discharge passages 6f, a relief valve 17 is provided which opens when the pressure in the supply/discharge passage 6d exceeds a limit value to relieve oil to the left and right wheel collective discharge passages. ... are connected to each other.

Furthermore, main accumulators 21, 21 for pressure accumulation are connected to the front and rear wheel side branch supply paths 6b, 6b'', respectively.
While accumulating the pressure of the oil discharged from the hydraulic pump 5,
It has a function of supplying oil from the front and rear wheel side branch supply passages 6b and 6b' to each of the left and right wheel branch supply passages 6c at a predetermined set pressure. In addition, the front/rear wheel side exhaust path 6g/6
g' have return accumulators 22 and 22, respectively.
is connected. These return accumulators 22
・22 is an image of the pressure when oil is discharged to the discharge passage 6e, the left and right wheel collective discharge passage 6f, and the front and rear wheel side discharge passages 6g and 6g'' in accordance with the switching operation of the control valve 7... , and absorbs the sudden rise in temperature, thereby suppressing the so-called water hammer phenomenon.

On the other hand, a pair of gas springs 23, 23 are arranged in parallel to each hydraulic cylinder 4, respectively. These gas springs 23, like each of the above-mentioned accumulators 21 and 22,
Oil chamber 23a and gas chamber 2 separated by bellows
3b, and each oil chamber 23a is connected to each hydraulic cylinder 4 through a communication passage 6m in which orifices 24, 24 are provided, respectively. Each gas chamber 23b is filled with gas, and by compressing the filled gas, relatively high-frequency pressure fluctuations within the hydraulic cylinder 4, that is, vibrations of the wheels 2 and 3, are absorbed. Furthermore, by making the orifices 24, 24 corresponding to the pair of gas springs 23, 23 have different flow characteristics from each other as described above, the configuration has vibration absorption characteristics over a wide range of frequencies. .

By the way, in order to quickly change the steering characteristics of the vehicle according to the detection results of the various sensors 8a, 8b, and 8C in the above-mentioned hydraulic system, a high system pressure of, for example, close to 160 kg/afl is required as described above. Pressure is required, and for this reason, a plunger pump is employed as the hydraulic pump 5. And this type of hydraulic pump 5
Since the variation in the discharge pressure, that is, the amplitude of the pulsation is large, a pulsation absorbing accumulator 25 for absorbing this pulsation is provided in the main supply path 6a by a filter 26 interposed therein, and a hydraulic pump 5. and the discharge side of the

The pulsation absorbing accumulator 25 has a structure in which the interior is divided into an oil chamber 25a and a gas chamber 25b, and a free piston 25c that is slidable along the inner wall surface is installed. The gas chamber 25b is filled with gas, and the free piston 25c responds to pressure changes in the main supply path 6a, thereby absorbing particularly relatively low frequency pressure fluctuations.
It is designed to smooth out the oil pressure in a.

Next, the arrangement of each of the above hydraulic devices in the vehicle body 1 will be explained with reference to FIG. 1.

Front side frames 31L and 31R extending in the front-rear direction and fenders 32L and 32R that cover the outside of these front side frames 31L and 31R are provided on both left and right sides of the front bottom surface of the vehicle body 1. Between the fender 32L and between the right front side frame 31R and the fender 32R, wheel houses 33L and 33R are provided at positions corresponding to the left and right front wheels 2 and 2, respectively. Hydraulic cylinders 4, 4 for the front wheels are connected to strut towers 34L, 34R, each having an upwardly bulging shape at the center of these wheel houses 33L, 33R, respectively.

On the other hand, rear wheels 3 are mounted on both left and right sides of the rear side of the vehicle body 1, respectively.
- A wheel house inner panel (only the right side is shown) 35 is provided at a position corresponding to 3, and upwardly bulging strut towers 36L and 36R at the center of each of these wheel house inner panels 35 are provided at the rear. Hydraulic cylinders 4 for wheels are connected.

A front wheel equipment storage case 37 is arranged at the front end between the left front side frame 31L and the fender 32L. On the other hand, a reserve tank 11 is arranged at the front end between the right front side frame 31R and the fender 32R.

In addition, the wheel houses 33L and 33 on both the left and right sides of the vehicle body 1
Both left and right edges of the floor panel 39 are joined to side sills 38 (only the right side is shown) that extend in the front-rear direction between R and the wheel house inner panels 35L and 35R, and the rear cross member in this floor panel 39 An upwardly bulging portion 42 is formed at the rear of the exhaust pipe 40 and on the right side opposite to the exhaust pipe 41 . Inside this upper bulging part 42, a rear wheel side valve unit) IOR, a rear wheel side main accumulator 21 and a return accumulator 22 are installed.
A rear wheel side equipment storage case 43 is provided which stores the following.

On the other hand, the front side frames 31L on both the left and right sides
31R, that is, approximately at the center of the engine compartment, the engine 50 is installed via a vibration-absorbing mounting member consisting of a rubber mount (not shown) or the like. A hydraulic pump 5 driven by an engine 50 and a pulsation absorbing accumulator 25 are respectively attached.

An oil pipe constituting the oil passage 6 is provided between the installation locations of each of the hydraulic devices as described above.

First, the reserve tank 11 and the hydraulic pump 5 are connected by a suction pipe 51 that constitutes the suction passage 61. Further, the discharge port of the hydraulic pump 5 and the pulsation absorbing accumulator 25 adjacent to the hydraulic pump 5 are connected by a first pressure pipe 52, and the pulsating accumulator 25 is attached to the right front side frame 31R. The second pressure pipe 53 is connected to the filter 26 located therein.

The third pressure pipe 54 connected to the filter 26 is connected to the left and right front side frames 31L.
- Extends to the left side of the vehicle body 1 along the front cross member 55 that interconnects the front end portions of the 31R, and is connected to the front wheel side equipment storage case 37. The first, second, and third pressure pipes 52, 53, and 54 constitute the main supply path 6a. Said second pressure pipe 5
3, a pulsation absorbing hose 56, which will be described later, is interposed in a part thereof.

The front-wheel side equipment storage case 37 includes a left-front-wheel pipe 57 leading to the left-front hydraulic cylinder 4, and a left-front-wheel pipe 57 extending along the front cross member 55 and the right front side frame 31R to the right-front hydraulic cylinder 4. A right front wheel pipe 58 leading to the reserve tank 11 is connected to a front wheel return pipe 59 leading to the reserve tank 11, and a fourth pressure pipe branched from the third main pressure pipe 54 within this front wheel side equipment storage case 37. 60 are connected. This fourth pressure piping 60 is connected to the front cross member 55
The fourth pressure pipe 60 extends rearward along the right side of the vehicle body 1 and is connected to the rear wheel equipment storage case 43, and the fourth pressure pipe 60 constitutes the rear wheel branch supply path 6b'. There is.

In addition, the rear wheel side equipment storage case 43 has a rear wheel return pipe 61 leading to the reserve tank 11, a left rear wheel pipe 62 leading to the left and right rear wheel hydraulic cylinders 4, and a right A rear wheel pipe 63 is connected thereto.

FIG. 2 shows a sectional view of the pulsation absorbing hose 56. This pulsation absorbing hose 56 has two inner tubes 72 each having an outer diameter smaller than the inner diameter of the hose body 71 inserted into a hose body 71 made of a rubber tube from both ends toward the center. It has a structure. Fittings 73, 73 are attached to both sides of the hose body 71, respectively, and the ends of the inner pipes 72, 72 are crimped and fixed in the nipples 73a, 73a of these fittings 73, 73. There is. The free ends of the inner tubes 72 and 72 on the center side face each other with a predetermined gap in between. In such a pulsation absorbing hose 56, a part of the flow that passes through the inner tube 72 from one side and expands to its free end flows into the inner tube 72 facing the other side. The flow is divided into those flowing into the gaps 74 between the inner pipes 72 and the hose body 71.

In this case, the gaps 74 act as closed pipes, so the flow is reflected and the phase is reversed. In this way, a flow with an inverted phase is generated internally, and by interfering with this flow, pulsations in the fluid are absorbed.

In the above configuration, the ignition key switch is
When the engine 50 is in operation due to the N operation, oil is discharged from the hydraulic pump 5 driven by the engine 50, and this oil is supplied to the pulsation absorbing accumulator 2.
After passing through 5, it is supplied to each main accumulator 2 and 21 side. These main accumulators 21 and 21
Then, pressure is accumulated to a line pressure within a predetermined range, and oil at that pressure is supplied to each pressure line (front/rear wheel branch supply passages 6b, 6b', left and right wheel branch supply passages 6c, etc.). . In addition, each electromagnetic switching valve 16 is turned ON by the ON operation of the above-mentioned ignition key switch, and accordingly, each shutoff valve 15, which was in a closed state, is switched to an open state, and each supply/exhaust valve is turned on. Passage 6d... is opened. The vehicle height detected by the vehicle height sensor 8a, the vertical acceleration of the vehicle body 1 detected by the acceleration sensor 8b,
Based on the oil pressure detected by the pressure sensor 8C,
The control unit 9 controls the operation of each control valve 7 . These control valves 7 supply high-pressure oil to each hydraulic cylinder 4, or discharge oil, thereby changing and adjusting the suspension characteristics of the vehicle to predetermined characteristics.

As described above, in the above embodiment, the oil discharged from the hydraulic pump 5 is supplied to the main accumulators 21 through the pulsation absorbing accumulator 25. That is, as described above, large pulsating oil is discharged from the hydraulic pump 5 which is a plunge pump, but this pulsating change is absorbed by the pulsation absorbing accumulator 25 and the smoothed oil is sent to the main accumulator 21. It is supplied to the 21 side. In this case, the pulsation-absorbing accumulator 25 is configured to have absorption characteristics for low-frequency pulsations with large amplitudes, but its ability to absorb high-frequency pulsations is low. Therefore, by further providing a pulsation absorbing hose 56 with a high ability to absorb high frequency pulsations as an outflow pipe from the pulsation absorbing accumulator 25, it is possible to supply oil with suppressed high frequency pulsations as well as low frequencies. It will be done. In this way, the operation of the main accumulators 21 and downstream devices below 21 is controlled using the supplied oil that is sufficiently smoothed over almost the entire frequency range. As a result, the suspension characteristics can be controlled stably, and the main accumulators 21 and 21 directly attached to the vehicle body 1 can
Since the following equipment does not become a secondary source of vibration or generate noise, a more comfortable ride can be provided to the occupants.

Further, the pulsation absorbing accumulator 25 as described above is
When the pulsating oil flows into this, the pulsation absorbing accumulator 25 itself vibrates, but in the above embodiment, the pulsating absorbing accumulator 25 is attached to the engine 5o. That is, engine 5
Since o is the largest source of vibration, as mentioned above, with a vibration absorbing member such as a rubber mount,
The vehicle body 1 is installed in such a way that the influence of vibration on the vehicle body 1 is minimized. By attaching the pulsation absorbing accumulator 25 to the engine 50, there is no need for a dedicated vibration prevention structure for attaching the pulsation absorbing accumulator 25, and therefore, installation with a simpler configuration is possible. As a result, for example, assembly workability is improved and manufacturing costs can be reduced.

〔Effect of the invention〕

As described above, the vehicle suspension device of the present invention has the following features:
A pulsation absorbing accumulator is connected between a pressure accumulating main accumulator connected to the discharge side of the hydraulic pump and attached to the vehicle body, and the discharge side of the hydraulic pump,
A pulsation absorption hose is interposed in the piping from this pulsation absorption accumulator to the main accumulator, and
The pulsation absorbing accumulator is attached to the engine.

As a result, the pulsation on the low frequency side of the oil discharged from the hydraulic pump is absorbed by the pulsation absorbing accumulator, and the pulsation on the high frequency side is absorbed by the pulsation absorbing hose, allowing oil with extremely small pressure fluctuations. It becomes possible to supply As a result, it is possible to control the suspension characteristics with higher control accuracy, and vibration and noise in the control equipment that receives this pressure oil are suppressed, improving ride comfort. Furthermore, since the pulsation-absorbing accumulator, which vibrates due to the inflow of pulsating oil from the hydraulic pump, is attached to the engine, a dedicated vibration-prevention mounting structure for the pulsation-absorbing accumulator is no longer required. This has the effect that the mounting structure can be made simpler.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention. FIG. 1 is a plan view of the arrangement structure of the hydraulic system viewed from above the vehicle body. FIG. 2 is a sectional view of a pulsation absorbing hose installed in the oil passage of the hydraulic system. FIG. 3 is a schematic side view schematically showing the overall configuration of the suspension device. FIG. 4 is a hydraulic circuit diagram showing the configuration of the hydraulic system. 1 is a vehicle body, 4 is a hydraulic cylinder, 5 is a hydraulic pump 21 is a main accumulator, 25 is a pulsation absorbing accumulator, 50 is an engine, and 56 is a pulsation absorbing hose. Figure 2 Figure 3

Claims (1)

[Claims] 1. Hydraulic cylinders are provided between the sprung mass and the unsprung mass, and the suspension characteristics can be changed by controlling the supply and discharge of oil discharged from a hydraulic pump driven by the engine to the hydraulic cylinders. In a suspension system for a vehicle, a pulsation absorbing accumulator is connected between a main accumulator for accumulating pressure connected to the discharge side of the hydraulic pump and attached to the vehicle body, and a pulsation absorbing accumulator connected to the discharge side of the hydraulic pump. A suspension device for a vehicle, characterized in that a pulsation absorbing hose is interposed in the piping leading from the main accumulator to the main accumulator, and the pulsation absorbing accumulator is attached to the engine.