JP2922262B2 - Hydraulic control device for garbage truck - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention uses a hydraulic control device for a refuse collection vehicle, in particular, a variable displacement hydraulic pump, which is always driven via a flywheel PTO. The present invention relates to a hydraulic control device for a refuse collection vehicle in which a body is held at a lowered position during traveling to prevent the floating.

[Conventional technology]

For example, Japanese Patent Publication No. Hei 1-57001 is known as one in which the cost is reduced by directly connecting a variable displacement pump to the flywheel PTO without using an expensive electromagnetic clutch. This is achieved by disposing an electromagnetic valve in the discharge line of the hydraulic pump and switching this electromagnetic valve to close the discharge line when the garbage truck is running, thereby reducing the discharge amount of the hydraulic pump to zero. The power is set to zero.

Further, in order to enhance the locking force of the body 1 and prevent the body 1 from floating when the garbage truck is running, a body lock device 15 is provided between the body 1 and the sub-frame 12 attached to the chassis frame 11. Is generally used (see FIG. 2).

This is because, although the center of gravity of the body 1 and the tailgate 2 is usually located forward of the dump fulcrum (dump shaft 10), heavy debris is loaded behind and the tailgate 2 When heavy dust is piled inside, the center of gravity may move backward from the dump fulcrum, and the body 1 may rise. In addition, most of various loading devices, such as a container tilting device for charging dust in the container into the tail gail 2 and a hopper and a hopper tilting device of a dust collector with a crane, are attached to the rear portion of the tailgate 2. Therefore, the lifting of the body 1 due to the movement of the center of gravity is worse. In particular, while the garbage truck is traveling, vertical movement during traveling is also added,
This is because the body 1 is more likely to float.

Here, conventionally used body lock device
No. 15 is designed to be held by this force using spring force in view of cost requirements and the like.

[Problems to be solved by the invention]

However, in the body lock device using the above-mentioned spring force, in order to surely prevent the body from floating, if the lock force is to be increased, it is necessary to increase the dump force to overcome the lock force, resulting in an increase in weight and cost. There was a problem that would lead to.

In view of the above, the present invention can enhance not only the locking force for preventing the body from floating during traveling without affecting the dumping force for dumping the body, but also enhance the driving engine during traveling. An object of the present invention is to provide a hydraulic control device for a refuse collection vehicle that can reduce the load on the vehicle and reduce the influence on traveling.

[Means for solving the problem]

In order to achieve the above object, the present invention is a hydraulic control device for preventing a body supported so as to be dumpable with respect to a vehicle body from floating during traveling, and for raising and lowering the body to dump. A dump cylinder configured to block the discharge of pressure oil at the end of its stroke, an electromagnetic switching valve that controls pressure oil supplied to the dump cylinder, and a capacity that is driven by a traveling engine to supply the pressure oil A variable hydraulic pump, the discharge amount of the hydraulic pump is reduced when the discharge pressure of the hydraulic pump exceeds a predetermined value, and the discharge amount of the hydraulic pump is reduced based on the discharge amount of the hydraulic pump when the discharge pressure falls below the predetermined value. Discharge amount control means, a tailgate provided with a dust loading device and connected to the body, and a changeover switch for switching the operation of the dust loading device , And a detection switch for detecting that the running condition in which the body drops.

The electromagnetic switching valve is configured such that when the detection switch detects that the body is in a traveling state in which the body is lowered, and when the switching switch is placed at a neutral position where the dust loading device is not operated, the dump cylinder is activated. Pressure oil is supplied to the dump cylinder so as to make a stroke toward the side where the body is lowered.

[Action]

According to the present invention configured as described above, the detection switch detects that the body is in the traveling state in which the body is lowered, and when the changeover switch is set to the neutral position where the dust loading device does not operate, the electromagnetic changeover valve is activated. Supply pressure oil to the dump cylinder to lower the body. Thus, the body is urged to the lower side by the dump cylinder, so that it is possible to reliably prevent the body from rising during traveling.

At this time, when the dump cylinder reaches its stroke end and the discharge of the pressure oil is interrupted, the discharge pressure of the hydraulic pump increases. When the discharge pressure of the hydraulic pump exceeds a predetermined value, the discharge amount control means reduces the discharge amount of the hydraulic pump, so that the load on the traveling engine that drives the hydraulic pump is suppressed, and the influence on traveling is reduced. be able to.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 2, the refuse collection vehicle is provided with a tailgate 2 connected to the rear portion of the body 1, and in the tailgate 2, a garbage load including a rotary plate 3 and a pushing plate 4 is loaded. The device 5 is built in. The rotating plate 3 is rotated by the drive of the rotating plate hydraulic motor 6, and the pressing plate 4
Is made to swing up and down by the expansion and contraction of the pushing plate cylinder 7.

The tailgate 2 swings up and down by driving the tailgate lift cylinder 8, and the body 1 moves between the subframe 12 on the chassis frame 11 around the dump shaft 10 by driving the dump cylinder 9. Dump and
A body is provided between the body 1 and the sub-frame 12 to prevent the body 1 from floating during traveling while being locked by the drive of the automatic lock cylinder 14 of the automatic lock device 13. The lock device 15 is mounted.

Further, a detection switch 16 is provided on a side surface of the subframe 12,
Detection plates 17 are fixed to the position of the body 1 corresponding to the detection switches 16, respectively. When the body 1 is lowered, the detection plate 17 suppresses the detection switches 16 and detects them.

FIG. 3 shows a hydraulic circuit diagram, in which the actuators 6, 7, 8, 9, and 14 are operated by switching control solenoid valves V1 to V5 provided in the hydraulic circuit 18. And is directly connected to the flywheel PTO and rotated by this drive to rotate the actuators 6, 7, 8, 9,
14 is provided with a hydraulic pump P for supplying pressure oil from a hydraulic oil tank T.

 The details of the hydraulic pump P are shown in FIG.

That is, the hydraulic pump P includes a pump body 20 and a spring 2 that changes the tilt angle of the swash plate 20a of the pump body 20.
1a built-in first control cylinder 21 and second control cylinder 22
, A constant flow holding control valve 23, a constant pressure holding control valve 24, and a fixed throttle flow control valve 25.

The constant flow holding control valve 23 is set to operate when a differential pressure generated before and after the flow control valve 25 reaches ΔP. That is, when the pump body 20 rotates at a high speed due to the acceleration of the accelerator, the discharge amount increases, and when the differential pressure across the flow control valve 25 reaches ΔP, the constant flow holding control valve
Reference numeral 23 indicates that the state is switched rightward from the state shown in the figure.

When the constant flow holding control valve 23 is switched in this manner,
The ports a and c communicate with each other, and the constant pressure holding control valve 24
When the pilot pressure acts on the base side of the second control cylinder 22 through the b port and the c port of this pump, and this pilot pressure overcomes the elastic force of the spring 21a built in the first control cylinder 21, The plate is pushed counterclockwise from the state shown in the figure, whereby the discharge amount of the pump body 20 decreases until the differential pressure across the flow control valve 25 becomes equal to or less than ΔP.

When the discharge amount decreases and the differential pressure across the flow control valve 25 becomes ΔP or less, the constant flow holding control valve 23 returns to the state shown in the figure, and the swash plate 20a of the pump body 20 Is returned in the clockwise direction by the elastic force of the spring 21a built therein.

Here, since the flow control valve 25 is a fixed throttle, the differential pressure across the flow control valve 25 is kept constant at ΔP by the above operation, so that a constant flow can be maintained.

The constant pressure holding control valve 24 is set to operate when the discharge side pressure reaches the maximum working pressure. That is, when the garbage is fully loaded, the circuit pressure reaches the maximum working pressure,
The constant pressure holding control valve 24 switches from the state shown in the figure to the right.

Then, when the constant pressure holding control valve 24 switches as described above,
The port a and the port c communicate with each other, and the second control cylinder 22
Pilot pressure acts on the base side of the pump body 20 to set the inclination angle of the swash plate 20a of the pump main body 20 to zero and set the discharge amount to zero.

In this case, if the load does not decrease, the constant pressure holding control valve
24 remains switched, so the pressure in the circuit is
It is possible to maintain a state in which the discharge amount is set to zero while maintaining the maximum working pressure.

In this state, if the load decreases and the circuit pressure becomes smaller than the maximum working pressure, the constant pressure holding control valve 24 returns to the state shown in the figure, and the swash plate 20a is moved by the elastic force of the spring 21a of the first control cylinder 21. Will return to the state shown in FIG.

As described above, since the constant pressure holding control valve 24 is incorporated in the hydraulic pump P, no relief valve generally used for regulating the maximum working pressure is provided.

 FIG. 1 shows an electric circuit diagram for controlling the hydraulic circuit.

That is, the main switch 26, the detection switch 16 and the relay coil CR-1 are connected in series, and a changeover switch 27 for switching between loading and discharging is connected to the main switch 26 and provided. The changeover switch 27 is connected in parallel with a loading circuit 28, a tailgate lift circuit 29, a body lowering switch 32 for operating a body raising circuit 30 and a body lowering solenoid 31, and further a relay coil CR-2. I have.

And the normally open relay contact of the relay coil CR-1
Cr-1a and normally closed relay contact Cr-2b of relay coil CR-2
Are serially connected between the main switch 26 and the body lowering solenoid 31, that is, the main switch 26, both relay contacts Cr-1a, Cr-2b, and the body lowering solenoid 31 are connected in series.

As a result, the body 1 is lowered, the detection switch 16 is turned on, and the main switch 26 is turned on.
When the switch 27 is in the neutral position, a current flows through the relay coil CR-1 and the normally open relay contact Cr-1a closes, whereby the body lowering solenoid 31 is actuated, and as shown in FIG. The electromagnetic valve V2 moves rightward, thereby lowering the body 1 via the dump cylinder 9. When the changeover switch 27 is switched from the neutral position to the loading or discharging side, a current flows through the relay coil CR-2,
As a result, the normally closed contact Cr-2b is opened so that normal work can be performed.

 Next, the operation of the above embodiment will be described.

Since the body 1 is lowered during traveling, the detection switch
16 is in the ON (closed) state, and the changeover switch 27 is in the neutral position (generally, the changeover switch 27 is always in the neutral position to prevent malfunctions except when performing loading or discharging operation). Back.) Therefore, when the main switch 26 is closed in this state, a current flows through the relay coil CR-1, the relay contact Cr-1a is closed, and a current flows through the body lowering solenoid 31. Then, the electromagnetic switching valve V2 for the dump cylinder 9 is switched to the right from the state shown in FIG. 3, so that the pressure oil flows to the rod side of the dump cylinder 9 and the body 1 is maintained in a completely completed state. 1 acts so as not to float.

At this time, the dump cylinder 9 has reached the maximum working pressure instantaneously because the lowering of the dump cylinder 9 is completed (locked at the stroke end) and the output circuit is shut off.
The operation of the constant pressure holding control valve 24 of the dump cylinder 9
Maintains the descent completion state at the maximum operating pressure, and the hydraulic pump P
Is zero.

Then, when the changeover switch 27 is switched to the discharging or loading side, electricity flows to the relay coil CR-2, and this relay contact
Since Cr-2b is opened and the electricity from this circuit stops flowing to the body lowering solenoid 31, the dump cylinder 9 returns to the position shown in the figure, and normal loading and discharging operations can be performed.

As shown in FIG. 5, some refuse collection vehicles are provided with a hopper loading device 33 behind the tailgate 2. That is, the hopper input device 33 is provided with a hopper 35 rotatably connected to the tail gate 2 via the pin 34.
And a hopper cylinder 37 having a base end rotatably supported by the tail gate 2 via a pin 36 and a tip end rotatably connected to the hopper 35. Thereafter, the refuse is swung upward to put dust into the tailgate 2.

In the case of such a refuse collection vehicle, if the hopper 35 is tilted and stored while traveling, the hopper 35 may be opened by receiving wind pressure from the front thereof.

Therefore, the hopper cylinder 37
In other words, by adopting a configuration in which the hopper cylinder 37 is replaced with the dump cylinder 9, the hopper 35 is fixed by the strong holding force of the hopper cylinder 37 during traveling, and the hopper 35 is opened by wind pressure. Can be prevented.

FIG. 6 and FIG. 7 show another embodiment, and the differences from the above embodiment are as follows.

That is, in this embodiment, a relief valve 38 is provided in the hydraulic circuit 18, and a hydraulic pump between the electromagnetic switching valve V2 for the dump cylinder 9 and the electromagnetic switching valve V3 for the rotary plate hydraulic motor 6 is provided. A pilot pipe 39 is provided between the pilot pipe 39 and P ′. And this pilot pipe 39
The constant pressure holding control valve 24 is omitted by causing the pilot pressure from the controller to act on the constant flow rate holding control valve 23.

In the case of this embodiment, the holding force at the maximum working pressure cannot be obtained, but the discharge amount of the hydraulic pump P 'can be made zero by only the constant flow holding control valve 23.

〔The invention's effect〕

Since the present invention is configured as described above, when the main switch is closed when the vehicle is traveling in a state where the body is completely lowered, the discharge amount of the hydraulic pump becomes zero, thereby affecting the traveling as a very small driving force. And at the same time hold the body in the descent completed state via the dump cylinder,
As a result, it is possible to reliably prevent the body from floating during traveling by increasing the locking force.

Also, by switching the switching valve from the neutral position,
By releasing the holding of the body by the dump cylinder, the influence on the dumping force can be eliminated.

Moreover, there is an effect that the above operation can be performed without using an existing hydraulic circuit and adding an electromagnetic valve or the like thereto.

[Brief description of the drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is an electric circuit diagram, FIG. 2 is a side view of a garbage truck, FIG. 3 is a hydraulic circuit diagram, and FIG. 4 is a hydraulic pump. FIG. 5 is a side view showing another example of a refuse collection vehicle in a main part, FIGS. 6 and 7 show another embodiment, and FIG. 6 is a diagram corresponding to FIG. FIG. 7 is a diagram corresponding to FIG. 1 ... body, 2 ... tailgate, 3 ... push plate, 4
... Rotating plate, 5 ... Dust loading device, 6 ... Rotating plate hydraulic motor, 7 ... Push plate cylinder, 8 ... Tail gate lift cylinder, 9 ... Dump cylinder, 13 ... Automatic locking device, 14 …… Automatic lock cylinder, 15 …… Body lock device, 16 …… Detection switch, 20 …… Pump body, 20a…
... swash plate, 21 ... first control cylinder, 21a ... spring, 22 ... control second cylinder, 23 ... constant flow holding control valve, 24 ... constant pressure holding control valve, 25 ... flow control valve, 26…
… Main switch, 27… Changeover switch, 31… Body lowering solenoid, 33 …… Hopper loading device, 37 …… Hopper cylinder, 38 …… Relief valve, 39 …… Pilot piping.

Claims (1)

(57) [Claims] 1. A hydraulic control device for preventing a body supported so as to be able to be dumped with respect to a vehicle body to float during traveling, wherein hydraulic oil is provided at a stroke end for lifting and lowering the body. A dump cylinder configured to block the discharge of oil, an electromagnetic switching valve for controlling pressure oil supplied to the dump cylinder, and a variable displacement hydraulic pump driven by a traveling engine to supply the pressure oil. A discharge amount control means for reducing the discharge amount of the hydraulic pump when the discharge pressure of the hydraulic pump exceeds a predetermined value, and returning the discharge amount of the hydraulic pump to the original value when the discharge pressure falls below the predetermined value; A tailgate built in the garbage loading device and connected to the body; a changeover switch for switching the operation of the garbage loading device; A detection switch for detecting that the vehicle is in a running state, wherein the electromagnetic switch valve detects that the body is in a running state in which the body is lowered, and the changeover switch is connected to the refuse loading device. The hydraulic control device for a refuse collection vehicle is characterized in that when it is placed in a neutral position in which the dump cylinder is not operated, the dump cylinder supplies pressure oil to the dump cylinder so that the dump cylinder strokes toward the lowering side of the body.