JPH03286033A - Dynamic damper of vehicle - Google Patents

Abstract

PURPOSE:To restrain oscillation of a vehicle body effectively by installing accumulators which hold a driver's seat device through holding cylinders so as to oscillate, and controlling the number of the accumulators which are connected with the holding cylinders. CONSTITUTION:There are provided plural accumulators 25 which hold a driver's seat device 9 installed in a vehicle body 1 through holding cylinders 22, 22 so as to oscillate. Next, a control valve 24 which controls the number of the accumulators 25 connected with the holding cylinders 22, 22 is provided at a fluid passage which connects the holding cylinders 22, 22 with the accumulators 25. The driver's seat device 9 is oscillated against spring action of the accumulators 25 and dampling effect due to pressure loss at a hydraulic circuit to restrain oscillation of a vehicle and damp oscillation of the driver's seat device 9 early. Besides, the change in mass of a main oscillation system meets the change in the number of the accumulators 25 to maintain the characteristic frequency in an optimum condition all the time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dynamic damper for a vehicle such as a wheel loader.

(Prior Art) As a dynamic damper for a wheel loader, there is, for example, one shown in Japanese Patent Application Laid-Open No. 63-265023.

In this device, the load-holding oil chamber of the boom cylinder in the working device is connected to an accumulator, and the working device, which serves as a mass member, and the accumulator, which acts as a spring, constitute a dynamic damper. Pitching, bouncing, etc. of the vehicle body are suppressed.

By the way, with 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 high-pressure hydraulic oil, and therefore it is necessary to provide an on-off valve between the boom cylinder and the accumulator. was there.

In addition, in the above-mentioned model, when the dynamic damper is activated, the load-side oil chamber needs to be in communication with the tank in order to allow the boom cylinder to expand and contract.
It was necessary to interpose a connecting means between the midway part of the load-side pipe and the tank to connect the two to a communicating state and a disconnected state.

(Problems to be Solved by the Invention) As mentioned above, in the conventional dynamic damper, in addition to the accumulator that constitutes the dynamic damper, it is necessary to have an on-off valve and a connection means, and the hydraulic circuit of the working device is complicated. Therefore, there was a problem that the cost was high.

Further, when changing from the traveling position to the working position or vice versa, it is necessary to operate the on-off valve and the connecting means, which is very troublesome.

Furthermore, if you forget to perform the above operation when transitioning from a working position to a running position, the dynamic damper will simply not operate; however, when transitioning from a running position to a working position,
If the above operation is forgotten, there is a problem that the accumulator will be damaged.

Therefore, it is necessary to have a safety device in case the user forgets to perform the above operation, or a device that automatically performs the above operation.
Furthermore, there is a problem of complicating the dynamic damper and increasing cost.

Furthermore, since an accumulator provided in the hydraulic circuit of the working device is used, there is also a problem in 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 problems.

(Means for Solving the Problems) In order to solve the above problems, the means adopted by the present invention are as follows:
The vehicle body is provided with a driver's seat device via a holding cylinder, a plurality of accumulators are connected to the holding cylinder to vibrately hold the driver's seat device via the holding cylinder, and a fluid passage between the holding cylinder and the accumulator is connected to the holding cylinder. , a control valve is provided for controlling the number of accumulators connected to the holding cylinder.

The vehicle body is equipped with a working part that can be raised and lowered via a lifting cylinder, and when the hydraulic pressure in the load holding side oil chamber of the lifting cylinder becomes large, an accumulator is connected to the holding cylinder by operating a control valve. In some cases, means for reducing the number of objects may be provided.

(Function) When the vehicle is running, depending on the undulations of the road surface, or
The vehicle tends to pitch or bounce when accelerating or decelerating.

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 pressure loss in the hydraulic circuit, suppressing pitching and bouncing of the vehicle, and Vibrations of the device are also quickly damped.

Additionally, if the mass of the main vibration system, which is made up of parts of the vehicle other than the driver's seat device, changes and the natural frequency of the main vibration system changes, the number of accumulators connected to the holding cylinder should be 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 explained based on the drawings of FIGS. 1 to 3. FIG.
and a working device 2 provided at the front of the vehicle body 1.

The vehicle body 1 includes a vehicle body 6 consisting of front and rear frames 4, 5, etc.
It has left and right front and rear wheels 7.8, a driver's seat device 9, etc.

Further, the working device 2 includes a pair of left and right booms 11 that are pivotably supported on the front frame 4 so as to be able to rise and fall freely, and the front frame 4 and each boom 1.
A pair of left and right boom cylinders 12 are interposed between the boom cylinders 12 and a packet 13 rotatably supported on the front end of the boom 11.
and a packet cylinder 14 interposed between the previous frame 4 and the packet 13.

By the way, the driver's seat device 9 is arranged above the front part of the rear frame 5, and includes a base 16, a control device 17 provided in the front part thereof, and a driver's seat provided in the rear part of the base 16. 18
etc.

The base 16 is disposed at the front part of the rear frame 5 so as to be movable in the vertical direction via guide rails 20, and the guide rails 20 are disposed in the left and right directions.

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

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-shaped accumulators 25 that constitute a spring. Cylinder 2 holding driver seat device 9
2 so that it can move up and down.

As described above, the dynamic damper 26 is
is configured.

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

The sleeve 27 has a pair of accumulator boats 31 arranged in parallel in the axial direction and connected to each accumulator 25.
and a single cylinder port 32 located between both accumulator boats 31 in the axial direction and connected to the oil chamber 23 of each holding cylinder 22 on the outer periphery.

Further, the left end portion of the sleeve 27 is connected to a head side oil chamber 33 which is a load holding side oil chamber in the boom cylinder 12 via a throttle valve 34 and a high pressure check valve 35.

The high pressure check valve 35 is configured so that when the pressure is high, the hydraulic oil is held in the cylinder 2.
This prevents the oil from flowing into the sleeve 27 from the head side oil chamber 33 of No. 2.

The spool 28 is slidably disposed in the sleeve 27 in the axial direction to enable the left accumulator boat 31 to be opened and closed. A biasing spring 29 is interposed.

According to the embodiment configured as described above, when the wheel loader is running, the wheel loader tends to pitch or bounce depending on the undulations 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 moves up and down while expanding and contracting, and as the holding cylinder 22 expands and contracts, the hydraulic oil in the oil chamber 23 of the holding cylinder 22 moves against the pressure of the sealed gas and flows into the accumulator 25.
The accumulator 25 acts as a spring as the hydraulic oil in the accumulator 25 flows into the oil chamber 23 in the holding cylinder 22 due to the pressure of the sealed gas.

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

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 that of the wheel loader. Therefore, pitching, bouncing, etc. of the wheel loader are suppressed, and the vertical movement of the driver's seat device 9 can be quickly damped by the damping effect due to the pressure loss of the hydraulic circuit.

By the way, the natural frequency of the main vibration system consisting of 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, the spring constants of the front and rear wheels 7.8, etc. , the natural frequency of the dynamic damper 26 is determined by the mass of the driver's seat device 9 and the operator, and
It is determined by the spring constant of the accumulator 25, etc.

Then, if the mass ratio and 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 is as low as possible, the wheel Regardless of the frequency of the external force acting on the loader, pitching and bouncing of the wheel loader can be effectively suppressed.

By the way, in the above case, the mass of the working device 2 is different depending on whether the bucket 13 of the working device 2 is not loaded with soil or sand, etc., and this causes the natural frequency of the main vibration system to change. are also different.

However, in the embodiment, the change in mass of the main vibration system is dealt with in the following manner.

That is, when there is no load loaded in the bucket 13, the mass of the main vibration system is lighter than when it is loaded.
The natural frequency is large.

In this case, since the pressure of the hydraulic oil in the head side oil chamber 33 of the boom cylinder 12 is low, the spool 2 of the control valve 24 is biased leftward by the spring 29, and both The accumulator port 31 communicates with the cylinder boat 32, which allows the dynamometer damper 26
The spring constant of the dynamic damper 26 becomes large, and the natural frequency of the dynamic damper 26 becomes large.

Moreover, when earth and sand etc. are loaded into the packet 13 of the working device 2,
The mass of the working device 2 becomes large, and the natural frequency of the main vibration system becomes small.

In this case, the head side oil chamber 33 of the boom cylinder 12
Since the pressure of the hydraulic oil inside is high, the spool 28 of the control valve 24 moves to the right against the spring 29 to close the left accumulator boat 31, as shown in FIG.

As a result, the spring constant of the dynamic damper 26 becomes small, and the natural frequency of the dynamic damper 26 becomes small.

In this way, the natural frequency of the dynamic damper 26 also changes in response to the change in the natural frequency of the main vibration system due to the presence or absence of a load in the packet 13 of the working device 2, so the natural frequency ratio of the two is , regardless of the size of the natural frequency of the main vibration system, it can be kept approximately constant, and therefore, regardless of the size of the natural frequency of the main vibration system, the peak of the resonance curve of the main vibration system can be lowered. Pitching and bouncing of the wheel loader can be satisfactorily suppressed regardless of the magnitude of the natural frequency of the vibration system and regardless of the frequency of the external force acting on the wheel loader.

Note that during work, the boom 11 is connected to the boom cylinder 12.
When raising the boom cylinder 12, hydraulic oil is supplied into the head side oil chamber 33, but at this time, the pressure of the hydraulic oil is high and the high pressure check valve 35 operates, and the head side No hydraulic oil flows into the sleeve 27 of the control valve 24 from the oil chamber 33, so there is no problem with the operation of the boom cylinder 12.

Note that the driver's seat device 9 may have a cabin 37, as shown by the imaginary line in FIG.

FIG. 4 shows a second embodiment of the present invention, in which a throttle valve 29 is interposed between the control valve and each accumulator 25, respectively.

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

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

Further, in the embodiment, the holding cylinder is a hydraulic cylinder, but it may be any other hydraulic cylinder.

Furthermore, the present invention is 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 vibably held in the vehicle body via the holding cylinder, the holding cylinder is connected to a plurality of accumulators, and the driver's seat device is Since the dynamic damper is composed of the device, holding cylinder, accumulator, etc., the structure is simple and can be manufactured at low cost, and there is no need to perform any operations when changing from the traveling position to the working position or vice versa. It is very convenient because there is no need to do any additional work, and moreover, in the case of a vehicle equipped with a working device, the dynamic damper can be operated even when the working device is operated by the hydraulic circuit.

Furthermore, even if the driver's seat device vibrates, the vibration can be quickly damped by pressure loss in the hydraulic circuit.

Furthermore, the main vibration system consists of the vehicle excluding the driver's seat equipment.

By setting the natural frequency ratio of both the main vibration system and the dynamic damper and the damping coefficient due to pressure loss in the hydraulic circuit so that the peak of the resonance curve of Even at this value, pitching and bouncing of the vehicle can be suppressed well.

In addition, in order to make the peak of the resonance curve of the main vibration system as low as possible, the number of accumulators connected to the holding cylinder can be changed to deal with changes in the natural frequency due to changes in the mass of the main vibration system. This can be dealt with by changing the natural frequency by changing the spring constant of the dynamic damper, and as a result, 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 kept approximately constant. Therefore, the peak of the resonance curve of the main vibration system can be lowered, and therefore pitching and bouncing of the vehicle can be suppressed favorably, regardless of the magnitude of the natural frequency of the main vibration system.

Further, as claimed in claim 2, if the hydraulic pressure in the load holding side oil chamber of the lifting cylinder is increased, a means is provided for operating the control valve to reduce the number of accumulators connected to the holding cylinder. It is convenient because it can automatically respond to changes in the natural frequency of the main vibration system caused by loading earth and sand onto the working section.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, in which FIG. 1 is a side view of a wheel loader, FIG. 2 is a hydraulic circuit diagram, and FIG.
This figure is a hydraulic circuit diagram of the main parts showing a position different from that in FIG. 2, and FIG. 4 is a hydraulic circuit diagram of the main parts 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...- Packet, 2
2... Holding cylinder, 24... Control valve, 25... Accumulator, 26... Group dynamic damper, 29... Throttle valve.

Claims (2)

[Claims] (1) A driver's seat device is provided in the vehicle body via a holding cylinder, a plurality of accumulators are connected to the holding cylinder to vibrately hold the driver's seat device via the holding cylinder, and a gap between the holding cylinder and the accumulator is connected to the holding cylinder. A dynamic damper for a vehicle, characterized in that a fluid passage is provided with a control valve that controls the number of accumulators connected to a holding cylinder. (2) The vehicle body is equipped with a working part that can be raised and lowered via an elevating cylinder, and when the oil pressure in the load holding side oil chamber of the elevating cylinder becomes large, the control valve is operated to connect to the holding cylinder. 2. The dynamic damper for a vehicle according to claim 1, further comprising means for reducing the number of accumulators.