JPH0471801B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an operation control device for a garbage collection vehicle.

(Prior Art) A hydraulic circuit for operating a garbage pushing means installed in a garbage collection vehicle is conventionally known, and this hydraulic circuit includes a hydraulic actuator (drive section) of the garbage pushing means that is supplied with pressure oil. A constant displacement hydraulic pump was used to supply this.

(Problem to be solved by the invention) However, the shaft power L required by the hydraulic pump to operate the above-mentioned garbage pushing means is L (KW) = P × Q / 612 (P: Kg / cm ² pressure, Q: /min flow rate) Therefore, when using the above-mentioned constant displacement pump, the pump should be selected assuming the maximum pressure and required flow rate commensurate with the maximum output required when the dust pushing means is activated, and the engine Idling speed (e.g. 600rpm)
It was used at higher speeds (eg 1500rpm).

Therefore, even if the load is small when the dust pushing means is in operation, the engine always supplies the power specified by the maximum pressure and required flow rate, which causes more energy than necessary to be consumed. In addition, since the engine speed is increased during use, there is a problem in that the noise level increases.

By the way, in general, in a garbage storage vehicle, the majority of the loading process is just feeding the garbage into the garbage storage box, and the load is small, so in reality, the garbage pushing means only needs a small output, and the garbage inside the garbage storage box is full. High power is only required at the end of the pushing stroke when the pressure is close to .

Therefore, by focusing on this point, the conventional drawbacks can be solved. In other words, during most of the loading process, the engine speed is kept low and the loading operation is carried out smoothly even when the hydraulic pump discharge flow rate is a large flow rate with a constant pressure.On the other hand, when the engine is fully loaded, the engine speed is kept low. High pressure is maintained by reducing the discharge flow rate of the hydraulic pump.

Note that although the operating speed when the tank is full is slow, it is only a short time compared to the entire loading process, so the operator does not notice it.

(Means for Solving the Problems) The present invention provides an operation control device for a garbage collection vehicle, which includes a garbage storage box placed on a chassis, and a loading box equipped with a garbage pushing means at the rear opening of the garbage storage box. A variable displacement pump is connected to the driving part of the garbage pushing means via a flow rate control valve, and this variable displacement pump pumps the garbage even at approximately idling speed. It has a control cylinder that is biased in the direction of discharging a flow rate Q1 that can drive the driving part of the pushing means, and furthermore, the pressure generated in the hydraulic circuit is such that the garbage stored in the garbage storage box is almost full. a constant pressure maintenance control valve that operates when the pressure reaches a predetermined pressure P1 or higher and reduces the discharge amount by the variable displacement pump to be less than the flow rate Q1; A constant flow rate maintenance control valve is connected to the control cylinder to reduce the flow rate to the above-mentioned flow rate Q1.

(Function) When the variable displacement pump is rotated with the engine speed kept low (for example, 600 rpm idling state) and the garbage pushing means pushes the garbage from the input box into the garbage storage box, the load acting on the garbage pushing means is reduced. During the pushing stroke at the beginning or middle stage of storing small pieces of garbage, the discharge flow rate is maintained at a large flow rate with low pressure, so that the garbage can be smoothly stored in the garbage storage box.

In addition, at the final stage of storage when the garbage storage box is nearly full and the load acting on the garbage pushing means increases, the constant pressure maintenance control valve is activated to reduce the discharge flow rate to a small flow rate to ensure high pressure. operate slowly.

On the other hand, when the engine speed becomes overspeed, even if the differential pressure across the flow rate control valve becomes large enough to switch the constant flow rate maintenance control valve, the constant flow rate maintenance control valve operates to discharge the discharge flow rate of the variable displacement pump. The large flow rate is controlled.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration of a garbage collection vehicle.

In Figure 1, 1 is a palm;
Above, a garbage storage box 3 having an opening 2 at the rear is freely pivoted 4 to the rear end of the chassis 1, and this garbage storage box 3 is connected to a dump cylinder disposed between the chassis 1 and the garbage storage box 3. It dumps appropriately by the expansion and contraction action of 5.

Reference numeral 6 denotes a charging box 7 which is pivotably supported above the opening 2 of the garbage storage box 3. Inside the charging box 6, a pushing plate 8, which constitutes a part of the trash pushing means, is pivotably supported. This input box 6 and push plate 8
In addition to being able to swing the pushing plate 8 back and forth by the expansion and contraction of the pushing plate actuating cylinder 10 as a drive unit disposed therebetween, the input box 6 can also be tilted.

Further, below the pushing plate 8, a rotary plate 12 constituting the other part of the dirt pushing means is rotatably mounted 13 by a hydraulic motor 11 as a driving part.

Reference numeral 14 denotes a lashing claw for lashing the input box 6 in the storage position. The engagement and disengagement are appropriately performed via the link mechanism 17 due to the expansion and contraction action of the link mechanism 16.

FIG. 2 shows a hydraulic circuit of an operation control device for a garbage collection vehicle according to the present invention.

In Fig. 2, Pc is a variable displacement pump which will be described later and is driven by an engine.The suction side of this variable displacement pump Pc is connected to an oil reservoir T, and the discharge side is used for operating the pushing plate via a variable flow rate control valve Qc. Switching valve V for cylinder 10 and lashing cylinder 16
2, connected in parallel to V3. Further, the discharge side of the variable displacement pump Pc is connected to the switching valve V3, and
Switching valve V for dump cylinder 5 and hydraulic motor 11
1, connected in series to V4.

By the way, the variable displacement pump Pc described above has a pump main body P and a first control cylinder 18.
, a second control cylinder 19 having a larger cross-sectional area than the first control cylinder 18 , a constant flow rate maintenance control valve 21 , and a constant pressure maintenance control valve 22 .

The first and second control cylinders 18 and 19 are connected to the swash plate in a scale-like manner so as to change the angle of inclination of the swash plate of the pump body P,
A spring 20 is housed in the piston chamber of the first control cylinder 18, which constantly extends the piston rod and biases the swash plate in the direction of increasing the discharge amount.

Further, the discharge side of the pump main body P is connected to the piston chamber of the first control cylinder 18, the operating portions of the constant flow rate maintenance control valve 21 and the constant pressure maintenance control valve 22, and the port a, respectively.

On the other hand, the piston chamber of the second control cylinder 19 is connected to the C port of the constant pressure maintenance control valve 22.

The constant flow rate maintenance control valve 21 is a hydraulic pilot-controlled two-position, three-port control valve, and normally the a port is closed and the b and c ports are in communication.

Further, the constant pressure holding control valve 22 is a hydraulic pilot control support two-position three-port control valve, and normally the a port is closed and the b port and c port are in communication.

Further, the c port of the constant flow rate control valve 21 and the port of the constant pressure control valve 22 are communicated with each other, the b port of the constant flow rate control valve 21 is connected to the oil reservoir T, and the discharge side of the variable flow rate control valve Qc is connected to the oil reservoir T. It is connected to the other operating section of the constant flow rate maintenance control valve 21.

Note that V5 is a relief valve and CK is a check valve.

Next, the operation of the garbage collection vehicle operation control device configured as described above will be explained.

By sequentially switching the switching valves V3 and V4, the rotating plate 12 starts rotating in the normal direction, the pushing plate 8 starts reversing, the pushing plate 8 stops reversing, the rotating plate 12 stops rotating normally (one rotation), and the pushing plate 8 starts rotating normally. A loading operation is performed in which one step is the start of pushing and the stopping of pushing of the pushing plate 8, and the garbage is stored in the garbage storage box 3.

During this time, the pressure generated is as shown in Figure 3.
When the rotary plate 12 is rotating normally, it is P2, and the pushing plate 8
When the reversal of is added, the pressure becomes P3, and when the pushing plate 8 is pushed in, the pressure becomes the maximum in one stroke, but specifically, the pressure varies depending on the amount of garbage stored in the garbage storage box 3, and it is normal when the amount of garbage stored is small. When pressed, set value
The pressure is within P1, but when the garbage is full, the pressure exceeds the set value P1 and reaches the maximum high pressure P4.

Next, as shown in Fig. 4, the discharge flow rate of the variable displacement pump Pc is as shown in Fig. 4, when there is enough room to accommodate the garbage in the garbage storage box 3, that is, in the pushing stroke at the beginning or middle of the storage, the pressure is less than the set value P1. The engine speed is maintained at a constant low speed (for example, idling at 600 rpm), and a variable displacement pump is used.
The discharge flow rate of Pc is maintained at a constant large flow rate Q1.

In addition, if you carelessly step on the accelerator and increase the engine speed more than necessary, the variable displacement pump Pc
The discharge amount of the variable flow control valve Qc tries to temporarily increase compared to the large flow rate Q1, but the pressure difference before and after the variable flow control valve Qc becomes large enough to switch the constant flow control valve 21, and as a result, the constant flow control valve 21 The a port and the c port communicate with each other, and the second control cylinder 1 is connected to the second control cylinder 1 via the b port and c port of the constant pressure maintenance control valve 22.
Pilot pressure also acts on the piston chamber No. 9, and the
Due to the difference in area between the second control cylinders 18 and 19, the second control cylinder 19 expands, the first control cylinder 18 contracts, and the swash plate changes to reduce the discharge flow rate.As a result, the original value is instantaneously restored. Balance to large flow rate Q1.

In this manner, the engine speed is kept low during the pushing stroke in the initial stage or middle stage of dust storage, and the discharge flow rate is balanced to the large flow rate Q1.

On the other hand, during the pushing stroke at the final stage of storage when the dust is sufficiently stored in the dust storage box 3, the pressure generated in the hydraulic circuit exceeds the set value P1 and reaches a maximum of P4, so this is set as the pilot pressure and the constant pressure maintenance control valve 22 is switched, and its a port and c port communicate with each other.
and the first and second control cylinders 1
As a result of the pilot pressure acting on both piston chambers 8 and 19, the second control cylinder 19 expands due to the difference in area between the two cylinders 18 and 19, while the first control cylinder 18 contracts and the swash plate controls the discharge flow rate. When the discharge flow rate decreases to a small flow rate Q2, the swash plate is stopped by an appropriate means (such as a stopper), and the discharge flow rate is not decreased thereafter. This ensures high pressure.

In this way, the pushing plate 8 operates slowly during the pushing stroke at the end of the storage when the garbage is sufficiently stored in the garbage storage box 3, but since the proportion of this stroke in the loading work is very small, the overall The loading time is almost the same as before.

In this example, two control cylinders are connected in a balance type manner, but the number and form of the control cylinders are not limited.

(Effects of the Invention) As described above, according to the present invention, the discharge amount of the variable displacement pump is set to Q1, which is a large flow rate, during most of the loading work from the initial stage to the middle stage of accommodation when the pressure generated in the hydraulic circuit is low. In addition, by setting the discharge flow rate to a small flow rate Q2 only at the end of the pushing stroke at the end of the accommodation period when the pressure generated in the hydraulic circuit increases, the power supplied from the engine to the variable displacement pump is set to be lower than that of conventional systems. Therefore, the engine speed can be lowered, and an energy-saving and low-noise garbage collection vehicle can be provided. Moreover, since the pushing stroke at the final stage of storage occupies a very small proportion of the total loading work, the overall loading work time is almost unchanged compared to the conventional method.

In addition, even if you inadvertently step on the accelerator and the differential pressure increases, the constant flow rate maintenance control valve allows you to instantly return to the original flow rate. It is possible to prevent the harmful effects that may occur, and it is possible to protect the hydraulic system and mechanism, and ultimately ensure safety.

[Brief explanation of the drawing]

1 to 4 illustrate embodiments of the present invention, and FIG. 1 is a side view of a garbage collection vehicle, FIG. 2 is a hydraulic circuit diagram, and FIG. 3 is a diagram of the relationship between pressure and time. FIG. 4 is a diagram showing the relationship between pressure and discharge flow rate. 3... Garbage storage box, 8... Pushing plate, 12... Rotating plate, 18... Control cylinder, 19...
Second control cylinder, Pc...variable displacement pump.

Claims (1)

[Scope of Claims] 1. A garbage collection vehicle in which a garbage storage box is placed on a chassis, and a charging box equipped with a garbage pushing means is tiltably connected to a rear opening of the garbage storage box, comprising: A variable capacity pump is connected to the drive unit of the means via a flow rate control valve, and this variable capacity pump discharges a flow rate Q1 capable of driving the drive unit of the dirt pushing means even at approximately idling rotation speed. It has a control cylinder that is biased in the direction, and is activated when the pressure generated in the hydraulic circuit reaches a predetermined pressure P1 or more when the garbage stored in the garbage storage box is almost full. a constant pressure maintenance control valve that reduces the discharge amount by the variable displacement pump below the flow rate Q1; and a constant flow rate that operates when the flow rate exceeds the flow rate Q1 and controls the discharge amount by the variable displacement pump to decrease to the flow rate Q1. An operation control device for a garbage collection vehicle, characterized in that a holding control valve is connected to a control cylinder.