JP2630661B2 - Rear axle suspension for industrial vehicles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a rear axle suspension device for mounting a rear axle on an industrial vehicle such as a forklift such that the rear axle can swing to the left and right.

[Conventional technology]

As an industrial vehicle, for example, a rear axle suspension device of a forklift is known as shown in FIGS.

In other words, a pair of left and right main frames 2
A pair of left and right brackets 3, 3 having a vertical plate shape and a rear end of the upper end surface protruding upward are provided at an upper portion of a rear end side thereof. The axle mounting plate 5 is mounted horizontally, and the vertical plate
A pair of front and rear horizontal shafts 7, 7 rotatably supported on the respective vertical plates 6 are fixed to the rear axle 8 so as to be swingable left and right, and then a pair of left and right rear wheel tires 9 are attached to the axle 8. , 9 and a swing stopper 10 fixed to the pair of left and right connecting plates 4 is opposed to the rear axle 8 to regulate the left and right swing of the rear axle 8.

 11 is a counter weight.

In such a rear axle suspension device, a mechanism for preventing the vehicle body 1 from excessively inclining left and right, a mechanism for locking left and right swing, a mechanism for adjusting the swing amount, and the like are known.

For example, as shown in Japanese Utility Model Laid-Open Publication No. 59-6503, a swing regulation mechanism provided with a stopper that interferes with the rear axle on the vehicle body side, Japanese Utility Model Publication No. 52-56987 and Japanese Patent Application Laid-Open No. 58-167214. As shown in JP-A-58-85526, a swing lock mechanism that connects a cylinder across the vehicle body and the rear axle and locks the rear axle so that the cylinder does not expand and contract. 2. Description of the Related Art There is known a mechanism in which a wedge-shaped slider is provided between a rear axle so as to be able to move forward and backward so that a swing amount can be adjusted.

[Problems to be solved by the invention]

However, each of the above-mentioned mechanisms is independent of each other, and it is not possible to simultaneously prevent excessive leaning of the vehicle body to the left and right, fix the rear axle, and adjust the swing amount, but also to satisfy them simultaneously. Each mechanism must be provided separately, which is not only large-scale, but also requires a large number of parts, resulting in high cost. In addition, the above-mentioned mechanisms cannot perform comprehensive and finer control according to the state of the vehicle.

Therefore, an object of the present invention is to provide a rear axle suspension device for an industrial vehicle that can solve the above-described problems.

[Means and actions for solving the problem]

According to the present invention, a rear axle 8 provided with a rear wheel tire 9 is connected to a center pin 7 rotatably supported at a rear portion of the vehicle body 1 so that the rear axle 8 and the vehicle body 1 can relatively swing left and right. A first chamber 23 in which the volume increases when the two swing relatively to the left and right around the rear portion of the vehicle body 1 and the support portion of the center pin 7, and decreases when the two swing relatively to the other left and right.
And a second chamber 24 in which the volume decreases when the two swing relatively to the left and right, and the volume increases when the two swing relatively to the other left and right. The first chamber 23 and the second chamber 24 Through a flow control valve whose passing flow rate is controlled from zero to a maximum by an external signal to supply pressure oil to the first chamber 23,
And a first position where the pressure oil in the second chamber 24 flows out to the tank;
A second position for supplying pressure oil to the second chamber 24 and discharging the pressure oil in the first chamber 23 to the tank, and a neutral position for shutting off the first chamber 23 and the second chamber 24 from the hydraulic pressure source and the tank, respectively. A rear axle suspension device for an industrial vehicle, comprising: a directional control valve that is switched to a second direction.

According to the present invention, when the vehicle body 1 and the rear axle 8 swing rightward or leftward, the volume of the first chamber 23 increases and the volume of the second chamber 24 decreases. It flows to the first chamber 23 through the control valve.

When the body 1 and the rear axle 8 swing left and right, the capacity of the first chamber 23 decreases and the capacity of the second chamber 24 increases.
The oil in 23 flows into the second chamber 24 through the flow control valve.

As described above, by controlling the pressure oil flow between the first chamber 23 and the second chamber 24, the relative swing of the rear axle 8 and the vehicle body 1 in the left-right direction can be regulated, so that the passage of the flow control valve By controlling the flow rate, an excessive inclination of the vehicle body to the left and right can be prevented, and the left and right swing of the rear axle 8 can be locked by setting the flow rate of the flow control valve to zero.

When the flow rate of the flow control valve is set to zero and the directional control valve is set to the first position, the pressure oil is supplied to the first chamber 23 and
And the rear axle 8 swings relatively to the left and right, and if the directional control valve is similarly set to the second position, pressurized oil is supplied to the second chamber 24 so that the vehicle body 1 and the rear axle 8 move relative to the other left and right. Rocks.

Accordingly, by setting the directional control valve to the first position or the second position in a state where the vehicle body 1 is tilted left and right, the tilt of the vehicle body 1 can be corrected by swinging the vehicle body 1 in a direction opposite to the tilt.

〔Example〕

As shown in FIG. 1, FIG. 2, and FIG.
The center pin 7 is provided with a vane 22 slidably in contact with an inner peripheral surface 21a of the space 21. The partition 21 and the vane 22 divide the space 21 into a first chamber 23 and a second space 23. The room is divided into 24 rooms.

Then, as shown in FIG. 4, each of the first chambers 23, 23 is filled with a fluid and communicates with a pipe 26 having a flow control valve 25, and each of the second chambers 24, 24 is filled with a fluid. The first and second directional control valves 28 and 29 allow the first and second directional control valves 28 and 29 to supply the pressure oil of the hydraulic pressure source P to each of the first chamber 23 and the second chamber 24.

The flow control valve 25 has a flow rate proportional to the voltage applied to the solenoid 25a, and the first and second directional control valves 28 and 29 are always in the shut-off position N and the first and second solenoids 28 ₁ , 28 ₂ and 29 ₁ ,
When energized 29 ₂ first and second pressurized oil supply position I, it is switched to II.

The solenoid 25a of the flow control valve 25 and the first and second solenoids 28 ₁ , 28 ₂ , 29 ₁ , 29 ₂ of the first and second directional control valves 28, 29
5 is controlled by a control device 30 as shown in FIG. 5. The control device 30 includes a vehicle speed sensor 31, a vehicle speed, a lateral acceleration sensor 32, a lateral acceleration, a swing angle sensor 33, a swing angle, and a height sensor 34. A work implement tilt operation signal is input by the work implement height and the tilt operation detection sensor 35, and based on the input, the energization control of each of the solenoids is performed.

The vehicle speed sensor 31 detects the rotation of the transmission output shaft and the like to detect the vehicle speed, the lateral acceleration sensor 32 is attached to the rear of the vehicle body to detect lateral acceleration, and the swing angle detection sensor 33 is connected to the vehicle body side. It is provided over the rear axle 8 to detect the relative swing angle between the two, the height sensor 34 detects the height of a working machine such as a fork claw, and the tilt operation detection sensor 35 has a fork claw. It detects that the mast has been tilted. For example, a contact sensor or a pressure sensor using a piezoelectric ceramic mounted on a tilt lever knob of a tilt cylinder operation valve detects that the operator has performed a tilt operation.

Thus, by controlling the flow rate of the flow rate control valve 25, the flow of the pressure oil between the first chamber 23 and the second chamber 24 is controlled, the rotation of the center pin 7 is restricted, and the right and left sides of the rear axle 8 are controlled. The swing can be limited, and the center pin 7 is rotated with respect to the vertical plate 6 by switching the first and second directional control valves 28 and 29 to supply pressure oil to the first chamber 23 or the second chamber 24. The rear axle 8 can swing right and left with respect to the vehicle body.

Therefore, by controlling each flow control valve and each direction control valve, an excessive inclination of the vehicle body to the left and right can be prevented, the swing of the rear axle 8 can be locked, and the swing amount of the rear axle 8 can be adjusted. it can.

 Next, the operation will be described.

Preventing excessive leaning of the vehicle to the left and right.

When traveling on uneven terrain, steps, etc., left and right rear tires 9,9
Receive different forces from the road surface, the rear axle 8 swings right and left around the sensor pins 7 and 7, and the rear axle 8
When the swing stoppers 10, 10 come into contact with the upper plate 8a of the rear axle 8 when the angle exceeds a certain angle with respect to the rear axle mounting plate 5, the operator experiences discomfort from the collision, and one of the front wheels rides on a protruding road surface. When the vehicle travels straight, the ride quality is poor and the operator feels uncomfortable.

Therefore, when the vehicle speed from the vehicle speed sensor 31 is equal to or higher than the set speed and the lateral acceleration from the lateral acceleration sensor 32 is equal to or lower than the set lateral acceleration, that is, when the vehicle is in a straight running state, the control device 30
As shown in FIG. 6, a voltage is supplied to the solenoid 25a of the flow control valve 25 in accordance with the vehicle size and the swing angle to control the flow rate.

Note that the vehicle class represents the size and weight of the vehicle body, and the vehicle class A
The size and weight are large in the class, and small in the car class B class.

As a result, the flow of pressurized oil between the first chamber 23 and the second chamber 24 is regulated by the flow control valve 25, and the relative left and right swinging between the vehicle body and the rear axle 8 is limited, so that the vehicle can travel during rough road surface running. Excessive leaning of the vehicle body to the left and right can be prevented, and the vehicle body roll caused by the swing amount control can be reduced.

Therefore, the swing stopper 10 becomes unnecessary, and an unpleasant phenomenon caused by the collision between the swing stopper 10 and the upper plate 8a of the rear axle 8, which has conventionally occurred, can be eliminated.

For the rocking lock of the rear axle 8.

When the mast is tilted after loading with the work machine at a high elevation, the left and right rear tires 9, 9 receive different forces from the road surface, respectively, and the center pins 7, 7, As a center, the rear axle 8 swings freely left and right, and as a result, the counterweight 11 swings right and left, which causes a problem such as uncomfortable rolling of the vehicle body.

Therefore, when the vehicle speed from the vehicle speed sensor 31 is lower than the set speed, the lift from the lift sensor 34 is higher than the set height, and a tilt operation signal is input from the tilt operation detection sensor 35, The passing flow rate is set to zero by setting the voltage to the solenoid 25a to zero.

As a result, pressure oil stops flowing between the first chamber 23 and the second chamber 24, and the sentan pin 7 cannot rotate with respect to the vertical plate 6, so that the relative axle of the rear axle 8 and the vehicle body 1 can be made. And the swing of the rear axle 8 can be locked.

 Therefore, it is possible to prevent the vehicle body from rolling.

When turning at a high speed on a level ground with respect to the adjustment of the swing amount, the counter weight 11 having a large mass tends to move outward due to the centrifugal force. There is a sense of stability.

Therefore, the lateral acceleration sensor 32 detects the amount of inclination (roll amount) caused by turning, and the lateral acceleration and the vehicle speed sensor 31 are used.
The vehicle speed is determined in advance by comparing the vehicle speed with the relationship data between the vehicle speed and the lateral acceleration set in the control device 30 to determine the degree of leaning of the vehicle body due to turning, and the vehicle body leaning that gives the operator a feeling of running instability. When entering the area to be corrected, the first and second directional control valves 28 and 29 are set to the first and second positions I and II to supply pressure oil to the first chamber 23 or the second chamber 24, and 24 or 1st room 23
And the vertical plate 6 is rotated to the right or left with respect to the center pin 7 to swing the vehicle body 1 in a direction opposite to the vehicle body inclination to correct the vehicle body inclination.

At this time, the voltage to the solenoids 25a, 26a, and 27a of the flow control valve 25 is set to zero, and the passing flow rate is set to zero.
The flow of pressurized oil between the chambers 24 is stopped.

As shown in FIG. 7, the first chamber 23 and the second chamber 24 formed by one vertical plate 6 and the center pin 7 may be communicated via a flow control valve 25.

〔The invention's effect〕

When the body 1 and the rear axle 8 swing left or right, the volume of the first chamber 23 increases and the volume of the second chamber 24 decreases, so that the oil in the second chamber 24 passes through the flow control valve and passes through the flow control valve. It flows into one room 23.

When the body 1 and the rear axle 8 swing left and right, the capacity of the first chamber 23 decreases and the capacity of the second chamber 24 increases.
The oil in 23 flows into the second chamber 24 through the flow control valve.

As described above, by controlling the pressure oil flow between the first chamber 23 and the second chamber 24, the relative swing of the rear axle 8 and the vehicle body 1 in the left-right direction can be regulated, so that the passage of the flow control valve By controlling the flow rate, an excessive inclination of the vehicle body to the left and right can be prevented, and the left and right swing of the rear axle 8 can be locked by setting the flow rate of the flow control valve to zero.

If the directional control valve is set to the first position with the flow rate of the flow control valve set to zero, the pressure oil is supplied to the first chamber 23 and
And the rear axle 8 swings relatively to the left and right, and if the directional control valve is similarly set to the second position, pressurized oil is supplied to the second chamber 24 so that the vehicle body 1 and the rear axle 8 move relative to the other left and right. Rocks.

Accordingly, by setting the directional control valve to the first position or the second position in a state where the vehicle body 1 is tilted left and right, the tilt of the vehicle body 1 can be corrected by swinging the vehicle body 1 in a direction opposite to the tilt.

[Brief description of the drawings]

1 to 6 show an embodiment of the present invention. FIG. 1 is a sectional view of a rear axle mounting portion, and FIGS. 2 and 3 are AA in FIG.
Line, BB line sectional view, FIG. 4 is a circuit diagram showing the communication state of each chamber, FIG. 5 is a control circuit diagram, FIG. 6 is a table showing the relationship between the flow rate of the flow control valve and the swing angle, FIG. 7 is an explanatory view of a modification, and FIGS. 8 and 9 are a front view and a rear view of a conventional example. 1 is a vehicle body, 7 is a center pin, 8 is a rear axle, 9 is a rear wheel tire, 23, 24 are first and second chambers, 25, 26, 27 are first, second, and third flow control valves, 28, 29 is a first / second directional control valve.

Claims (1)

(57) [Claims] 1. A rear axle 8 provided with a rear wheel tire 9 is connected to a center pin 7 rotatably supported on a rear portion of a vehicle body 1, so that the rear axle 8 and the vehicle body 1 can relatively swing right and left. Around the rear portion of the vehicle body 1 and the support of the center pin 7, the volume increases when the two swing relatively to the left and right, and decreases when the two swing relatively to the other left and right.
And a second chamber 24 in which the volume decreases when the two swing relatively to the left and right, and the volume increases when the two swing relatively to the other left and right. The first chamber 23 and the second chamber 24 Through a flow control valve whose passing flow rate is controlled from zero to a maximum by an external signal to supply pressure oil to the first chamber 23,
And a first position where the pressure oil in the second chamber 24 flows out to the tank;
A second position in which the pressure oil is supplied to the second chamber 24 and the pressure oil in the first chamber 23 flows out to the tank, and a neutral position in which the first chamber 23 and the second chamber 24 are shut off from the hydraulic pressure source and the tank, respectively. A rear axle suspension device for an industrial vehicle, comprising: a directional control valve that is switched over to a predetermined direction.