JP2602114B2 - Vehicle dynamic damper - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a dynamic damper for a vehicle such as a wheel loader.

(Prior Art) As a dynamic damper of a wheel loader, for example, there is a dynamic damper as disclosed in JP-A-63-265023.

In this device, the load holding side oil chamber of the boom cylinder in the working device is connected to the accumulator, and the working device serving as a mass member and the accumulator acting as a spring form a dynamic damper.
Pitching, bouncing and the like of the vehicle body during traveling are suppressed.

By the way, in the above, during excavation work, it is necessary to shut off the oil passage between the boom cylinder and the accumulator to protect the accumulator from the high-pressure operating shaft. was there.

Further, in the above-described one, when the dynamic damper is operated, the load side oil chamber needs to be in communication with the tank in order to allow the boom cylinder to expand and contract. In the meantime, it is necessary to interpose a connection means for connecting the two so as to be freely switched between a communication state and a cutoff state.

(Problems to be Solved by the Invention) As described above, in the conventional dynamic damper, in addition to the accumulator constituting the dynamic damper,
An on-off valve and connection means also need to be provided, and the hydraulic circuit of the working device becomes complicated, resulting in high costs.

Further, when shifting from the running posture to the working posture or vice versa, it is necessary to operate the on-off valve and the connecting means, which is also very troublesome.

Furthermore, if the operation is forgotten when shifting from the working position to the running position, the dynamic damper simply does not operate, but if the operation is forgotten when transferring from the running position to the working position, the accumulator There is a problem that is damaged.

Therefore, it is necessary to provide a safety device when the operation is forgotten, or a device for automatically performing the operation. However, there is a problem that the dynamic damper is further complicated and the cost is increased.

In addition, since the accumulator provided in the hydraulic circuit of the working device is used, there is a problem that the dynamic damper cannot be operated when the working device is operated by the hydraulic circuit during work.

An object of the present invention is to provide a dynamic damper for a vehicle that can solve the above problem.

(Means for Solving the Problems) In order to solve the above problems, a means adopted by the present invention is a vehicle in which a working unit is provided to be able to move up and down via an elevating cylinder. A driver's seat device is provided via a holding cylinder, and a plurality of accumulators for oscillatingly holding the driver's seat device via the holding cylinder are connected to the holding cylinder, and a fluid passage between the holding cylinder and the accumulator, A single control valve to control the number of accumulators to be connected,
The point is that means is provided for operating the control valve when the oil pressure in the load holding side oil chamber of the lifting cylinder becomes large, thereby reducing the number of accumulators connected to the holding cylinder.

(Operation) When the vehicle is driven, the vehicle tends to pitch or bounc according to the undulation of the road surface, or during acceleration or deceleration.

At this time, the driver's seat device of the dynamic damper vibrates against the spring action of the accumulator and the damping action due to the pressure loss of the hydraulic circuit to suppress pitching and bouncing of the vehicle, The vibration of the device is also attenuated early.

In addition, when the mass of the main vibration system constituted by a portion excluding the driver's seat device in the vehicle changes and the natural frequency of the main vibration system changes, the number of accumulators connected to the holding cylinder is changed. , Change the spring constant of the dynamic damper and change its natural frequency.

(Embodiment) Hereinafter, a first embodiment in which the present invention is applied to a wheel loader will be described with reference to FIGS. 1 to 3. FIG. 1 shows a wheel loader. And a working device 2 provided at a front portion of the vehicle body 1.

The vehicle body 1 includes a vehicle body 6 including front and rear frames 4, 5 and the like, front and rear wheels 7, 8 for a pair of left and right sides, a driver's seat device 9, and the like.

The working device 2 includes a pair of left and right booms 11 pivotally supported by the front frame 4 so as to be able to move up and down;
A pair of left and right boom cylinders 12 interposed between them, and a boom
A bucket 13 rotatably supported at the front end of a bucket 11 and a bucket cylinder interposed between the front frame 4 and the bucket 13
It has 14 mag.

The driver's seat device 9 is disposed above the front part of the rear frame 5, and includes a base 16, a control device 17 provided at the front part thereof, and a driver seat provided at the rear part of the base 16. It has 18 mag.

The base 16 is disposed at the front of the rear frame 5 via a guide rail 20 so as to be freely movable in the vertical direction. The guide rails 20 are disposed in a pair on the left and right.

Reference numeral 22 denotes a holding cylinder, which is a single-acting hydraulic cylinder, which is disposed on the left and right sides between the front portion of the rear frame 5 and the base 16, and has a hydraulic pressure 23 at its lower portion.

As shown in FIGS. 2 and 3, the oil chamber 23 of each holding cylinder 22 is connected via a control valve 24 to two bladder-type accumulators 25 constituting a spring, whereby the accumulator 25 The driver's seat device 9 is held via a holding cylinder 22 so as to be vertically movable.

As described above, the driver's seat device 9, the holding cylinder 22, and the accumulator 25 constitute the dynamic damper 26.

The control valve 24 is a 3 port 2 position switching valve, and the sleeve 27
, A spool 28, and a spring 29.

The sleeve 27 includes a pair of accumulator ports 31 that are arranged in the axial direction and are connected to the accumulators 25.
A single cylinder port 32 which is located between the accumulator ports 31 in the axial direction and is connected to the oil chamber 23 of each holding cylinder 22 is provided on the outer periphery.

Further, the left end of the sleeve 27 has a head side oil chamber 33 which is a load holding side oil chamber in the boom cylinder 12, a throttle valve 34,
It is connected via a high-pressure check valve 35. High pressure check valve 35
When the hydraulic pressure is high, the hydraulic oil is
The flow from 33 into the sleeve 27 is prevented.

The spool 28 is slidably disposed in the sleeve 27 in the axial direction so that the left accumulator port 31 can be opened and closed, and between the right ends of both the spool 28 and the sleeve 27, the spool 28 is disposed on the left. A biasing spring 29 is interposed.

According to the embodiment configured as described above, when the wheel loader travels, the wheel loader attempts to pitch or bounce according to the undulation of the road surface, or during acceleration or deceleration.

At this time, the driver's seat device 9 of the dynamic damper 26
The holding cylinder 22 is moved up and down while being expanded and contracted, so that the operating oil in the oil chamber 23 of the holding cylinder 22 flows into the accumulator 25 against the pressure of the sealed gas due to the expansion and contraction of the holding cylinder 22, and The hydraulic oil inside flows into the oil chamber 23 in the holding cylinder 22 by the pressure of the sealed gas, so that the accumulator 25 performs a spring action.

Further, due to the pressure loss of the hydraulic circuit, the vibration of the driver's seat device 9 is attenuated.

That is, the driver's seat device 9 moves up and down against the spring action of the accumulator 25 and the damping action due to the pressure loss of the hydraulic circuit, and the driver's seat device 9 moves up and down in the opposite phase to the wheel loader. Therefore, pitching and bouncing of the wheel loader are suppressed and the driver's seat device 9
Can also be attenuated early due to the damping effect of the pressure loss of the hydraulic circuit.

Incidentally, the natural frequency of the main vibration system including the wheel loader excluding the driver's seat device 9 is determined by the mass of the portion of the wheel loader excluding the driver's seat device 9 and the spring constants of the front and rear wheels 7, 8, and the like. , The natural frequency of the dynamic damper 26 depends on the mass of the driver's seat device 9 and the operator,
It is determined by the spring constant of the accumulator 25 and the like.

If the mass ratio and the natural frequency ratio of both the main vibration system and the dynamic damper 26 and the damping coefficient due to the pressure loss of the hydraulic circuit are set so that the peak of the resonance curve of the main vibration system becomes as low as possible, Regardless of the frequency of the external force acting on the loader, the pitching and bouncing of the wheel loader can be satisfactorily suppressed.

By the way, in the above case, the mass of the working device 2 differs between the case where earth and sand or the like is not loaded on the bucket 13 of the working device 2 and the case where it is loaded. Is also different.

However, the embodiment responds to the mass change of the main vibration system as described below.

That is, when no load is loaded in the bucket 13, the mass of the main vibration system is lighter and the natural frequency is higher than when the load is loaded.

In this case, since the pressure of the hydraulic oil in the head side oil chamber 33 of the boom cylinder 12 is low, as shown in FIG.
The spool 28 is urged to the left by a spring 29, and both accumulator ports 31 communicate with the cylinder port 32, thereby increasing the spring constant of the dynamic damper 26 and increasing the natural frequency of the dynamic damper 26. It will be great.

When earth and sand are loaded on the bucket 13 of the working device 2,
The mass of the working device 2 increases, and the natural frequency of the main vibration system decreases.

In this case, since the pressure of the hydraulic oil in the head side oil chamber 33 of the boom cylinder 12 is high, the spool 28 of the control valve 24 moves rightward against the spring 29 as shown in FIG. Then, the left accumulator port 31 is closed.

Thereby, the spring constant of the dynamic damper 26 becomes small, and the natural frequency of the dynamic damper 26 becomes small.

As described above, the natural frequency of the dynamic damper 26 also changes in accordance with the change in the natural frequency of the main vibration system due to the presence or absence of the load in the bucket 13 of the working device 2. Irrespective of the magnitude of the natural frequency of the main vibration system, it can be made substantially constant, so that the peak of the resonance curve of the main vibration system can be lowered regardless of the magnitude of the natural frequency of the main vibration system. Regardless of the magnitude of the natural frequency of the vibration system,
Regardless of the value of the frequency of the external force acting on the wheel loader, pitching and bouncing of the wheel loader can be favorably suppressed.

During operation, when the boom 11 is raised by the boom cylinder 12, hydraulic oil is supplied into the head-side oil chamber 33 of the boom cylinder 12, but in this case, the hydraulic oil pressure is high. , The high-pressure check valve 35 operates and the head-side oil chamber 33
Hydraulic fluid does not flow into the sleeve 27 of the control part 24 from
Therefore, there is no problem in the operation of the boom cylinder 12.

The driver's seat device 9 may have a cabin 37 as shown by a virtual line in FIG.

FIG. 4 shows a second embodiment of the present invention, in which throttle valves 29 are interposed between the control valves and the accumulators 25, respectively.

In the first embodiment, a valve for increasing the pressure loss of the hydraulic circuit is not particularly provided. However, if the throttle valve 29 is interposed as in the second embodiment, the damping coefficient of the dynamic damper 26 can be set to a desired value. Is easy to set.

In the embodiment, the number of accumulators is two, but may be three or more.

Further, in the embodiment, the holding cylinder is a hydraulic cylinder, but may be another hydraulic cylinder.

The present invention is also applicable to vehicles other than wheel loaders.

(Effects of the Invention) As described in detail above, according to the present invention,
The driver's seat device is held via a holding cylinder so that it can vibrate,
The holding cylinder is connected to a plurality of accumulators, and a dynamic damper is configured by the driver's seat device, the holding cylinder, the accumulator, etc., so that the structure is simple and can be manufactured at low cost. Or, on the contrary, there is no need to perform any operation when moving, which is very convenient, and in the case of a vehicle equipped with a working device, even when the working device is operated by a hydraulic circuit. , The dynamic damper can be operated.

Further, even if the driver's seat device is vibrating, the vibration can be attenuated early due to the pressure loss of the hydraulic circuit.

Furthermore, the natural frequency ratio of both the main vibration system and the dynamic damper, the damping coefficient due to the pressure loss of the hydraulic circuit, etc. are set so that the peak of the resonance curve of the main vibration system consisting of the vehicle excluding the driver's seat device is minimized. Then, no matter what the frequency of the external force acting on the vehicle is, the pitching and bouncing of the vehicle can be favorably suppressed.

Also, in the case where the peak of the resonance curve of the main vibration system is made as low as possible, for the change of the natural frequency due to the mass change of the main vibration system, the number of accumulators connected to the holding cylinder is changed, It can be handled by changing the natural frequency by changing the spring constant of the dynamic damper,
Thereby, even if the natural frequency of the main vibration system changes, the natural frequency ratio of both the main vibration system and the dynamic damper can be made substantially constant, and the peak of the vibration curve of the main vibration system can be lowered.
Therefore, regardless of the magnitude of the natural frequency of the main vibration system, pitching and bouncing of the vehicle can be favorably suppressed.

When the oil pressure in the load holding side oil chamber of the lifting cylinder becomes large, there is provided a means for operating the control valve to reduce the number of accumulators connected to the holding cylinder. This is convenient because it can automatically respond to changes in the natural frequency of the main vibration system due to the operation.

Furthermore, since the number of accumulators is controlled by a single control valve, the configuration of the hydraulic circuit can be simplified.

[Brief description of the drawings]

1 to 3 show a first embodiment of the present invention. FIG. 1 is a side view of a wheel loader, FIG. 2 is a hydraulic circuit diagram, and FIG.
The figure is a hydraulic circuit diagram of a main part showing a posture different from that of FIG. 2,
FIG. 4 is a hydraulic circuit diagram of a main part showing a second embodiment of the present invention. 1 ... vehicle body, 2 ... working device, 9 ... driver's seat device,
12 ... boom cylinder (elevating cylinder), 13 ... bucket, 22 ... holding cylinder, 24 ... control valve, 25 ... accumulator, 26 ... dynamic damper, 29 ... throttle valve.

Claims (1)

(57) [Claims] 1. A vehicle in which a working part is provided on a vehicle body so as to be able to move up and down via an elevating cylinder, wherein the vehicle body is provided with a driver's seat apparatus via a holding cylinder, and the holding cylinder is provided with a driver's seat apparatus. A plurality of accumulators that are held oscillatably via a holding cylinder are connected, and a single control valve that controls the number of accumulators connected to the holding cylinder is provided in a fluid passage between the holding cylinder and the accumulator, A dynamic damper for a vehicle, comprising: means for operating the control valve when the oil pressure in the load holding oil chamber becomes large to reduce the number of accumulators connected to the holding cylinder.