JPH0329617B2 - - Google Patents

Description

Detailed Description of the Invention The present invention provides a constant speed rotation control device for a rotating body, such as a rotating drum of a truck mixer (concrete mixer), which controls the rotation of a rotating body in a vehicle to a constant speed using a hydraulic motor. It is related to.

In general, a truck mixer rotates a rotating drum while traveling to mix the concrete materials put into the rotating drum before reaching the destination, and at the destination, the drum is reversed and the mixed concrete is discharged. This is how it was done.

Conventionally, as a rotational drive device for a rotating drum in such a truck mixer vehicle, a variable displacement hydraulic pump driven by an engine and a hydraulic motor that receives pressure oil from the hydraulic pump to rotationally drive the rotating drum are used. There is a known system in which the rotation of a rotary drum is controlled by changing the amount of pressure oil discharged from a hydraulic pump, and the variable displacement mechanism of the pump is fixed during concrete conveyance.

However, in this conventional system, since the hydraulic pump is used as a fixed displacement type during concrete conveyance, the rotation speed of the hydraulic motor, that is, the rotating drum, changes with fluctuations in engine rotation, causing the engine to operate at high speed. In this area, the rotating drum also rotates at high speed, which has a negative impact on the quality of the mixed concrete and the life of the drum itself, and increases the drive loss required for unnecessary rotation of the drum, which in turn reduces the running performance of the mixer truck. There were problems such as deterioration of the condition.

Therefore, the above-mentioned hydraulic pump is made into a variable displacement type, such as a swash plate type axial piston pump, and a motor rotation speed sensor is installed to detect the rotation speed of the hydraulic motor (rotating drum). By controlling the control amount of the variable control member of the pump (the swash plate angle in the case of a swash plate type axial piston pump) in accordance with the rotation speed signal, the pressure of the hydraulic pump can be maintained even if the engine speed increases. It is conceivable to keep the oil discharge amount substantially constant so that the rotary drum rotates at a constant speed regardless of engine rotational fluctuations.

However, in this case, since the hydraulic pump is feedback-controlled according to the rotation speed signal of the hydraulic motor (rotating drum), the hydraulic motor can be stably controlled in relation to the control amount of the variable control member of the pump, but the engine There is a delay in response in the rotation control of the hydraulic motor when the engine speed changes rapidly, and when the engine speed changes rapidly, the control amount of the variable control member of the pump accurately follows the change and the pump does not change. There is a problem in that the amount of pressure oil discharged fluctuates and the rotational speed of the rotary drum also fluctuates drastically.

In view of this point, the present invention basically provides a closed loop control system by performing feedback control of the control amount of the variable control member in the variable displacement hydraulic pump according to the rotation speed of the hydraulic motor as described above. Furthermore, it has a feed forward control that corrects the closed loop control according to the actual engine speed, which improves the responsiveness of the hydraulic pump to engine speed fluctuations, and even when the engine speed changes suddenly. The purpose of this system is to stably maintain the discharge amount of pressure oil from a hydraulic pump at a constant level without being affected by this, thereby making constant speed rotation control of the rotating drum (rotating body) effective. be.

For this reason, the configuration of the present invention includes a variable displacement hydraulic pump driven by an engine, a hydraulic motor that receives pressure oil from the hydraulic pump to rotationally drive a rotating body installed in a vehicle, and a variable displacement hydraulic pump driven by an engine. The engine rotation speed sensor detects the rotation speed of the hydraulic motor, the motor rotation speed sensor detects the rotation speed of the hydraulic motor, and the deviation between the motor rotation speed detected by this motor rotation speed sensor and a preset target value is determined, and this deviation is calculated. The deviation signal is corrected by the output signal from the engine rotation speed sensor by superimposing a value corresponding to the increase/decrease value of the engine rotation speed detected by the engine rotation speed sensor from the reference rotation speed, and this correction is performed. and a control circuit that controls the amount of pressure oil discharged from the hydraulic pump so as to maintain the rotational speed of the hydraulic motor at the target value based on the signal from the hydraulic motor. The system performs feedback control according to the engine speed to make the control system a closed loop, and also performs feedback control to make corrections depending on the engine speed.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a schematic configuration when the present invention is applied to a truck mixer vehicle (concrete mixer vehicle), in which 1 is an on-vehicle engine of the truck mixer vehicle, 2 is a rotating drum as a rotating body equipped on the mixer vehicle, The rotating drum 2 kneads the concrete material put into it by rotating in the normal direction, and discharges the mixed concrete by rotating in the reverse direction.

Reference numeral 3 denotes a swash plate type axial piston pump as a variable displacement pump driven by the engine 1, and the piston pump 3 has a swash plate, which is not shown, that is freely tiltable with respect to the input shaft. By changing the tilt angle of the swash plate, that is, the swash plate angle, and changing the displacement of each built-in piston, the amount of pressure oil discharged is controlled. The piston pump 3 is also equipped with an electromagnetic proportional solenoid valve 4 whose spool moves in proportion to the input current. The plate angle, that is, the amount of pressure oil discharged from the piston pump 3 is changed, and the direction of pressure oil discharge is switched.

Reference numeral 5 denotes a constant displacement hydraulic motor capable of forward and reverse rotation, and an output shaft 5a of the motor 5 is drivingly connected to the rotating drum 2. The pressure oil port of the hydraulic motor 5 is connected to the piston pump 3 via pressure oil passages 6, 6, and the pressure oil supplied from the piston pump 3 causes the hydraulic motor 5 to rotate in the forward and reverse directions to rotate the rotary drum 2. I'm trying to drive it.

Furthermore, 7 is an engine rotation speed sensor that detects the rotation speed R _E of the engine 1, 8 is a motor rotation speed sensor that detects the rotation speed R _M of the hydraulic motor 5 (rotation speed of the rotating drum 2), and 9 is the Each sensor 7,
The piston pump 3 receives an output signal from 8.
This is a control circuit that controls the amount of pressure oil discharged. As shown in the block diagram in FIG. 2, _this control circuit 9 uses a proportional, _integral , and A PID converter 10 converts the engine speed R E into a differential element (PID element), and converts the engine speed R _E from the engine speed sensor 7 into an output signal corresponding to the engine speed R _E and its preset reference speed. A first transmission element 12 outputs a voltage signal corresponding to an increase/decrease value from the number, and the output signal from the first transmission element 12 is added to the output signal from the PID converter 10, that is, the engine rotation speed R _E an adder 11 for superimposing a voltage signal corresponding to an increase/decrease value with respect to the reference rotation speed on a deviation signal between the target rotation speed R _O of the hydraulic motor 5 and the actual motor rotation speed R _M ; The second transmission element 13 converts the output signal into a corresponding output signal for controlling the electromagnetic proportional solenoid valve 4. Specifically, when the engine rotation is in an accelerating state, the adder 11 calculates the accelerating value from the reference rotation speed between the target rotation speed R _O of the hydraulic motor 5 and the actual motor rotation speed R _M. On the other hand, when in a deceleration state, the deceleration value is added to the deviation, thereby performing addition and subtraction in inverse proportion.

Therefore, the deviation signal between the motor rotation speed R _M detected by the motor rotation speed sensor 8 and the target rotation speed R _O is corrected by the output signal (engine rotation speed R _E ) from the engine rotation speed sensor 7, and the hydraulic motor 5 is Piston pump 3 to keep the rotation speed constant at its target value R _O
It is configured to control the amount of pressure oil discharged.

Next, to explain the operation of the above embodiment,
As the engine 1 operates, the piston pump 3 operates while maintaining a predetermined swash plate angle set by the control circuit 9 and discharges pressure oil, and the pressure oil discharged from the pump 3 has one pressure. The oil is supplied to the hydraulic motor 5 through the oil passage 6 to drive and rotate the hydraulic motor 5, and the rotation of the hydraulic motor 5 rotates the rotary drum 2 to mix concrete.

At this time, the rotation speed R _M of the hydraulic motor 5 is detected by the motor rotation speed sensor 8 and inputted to the control circuit 9 as a motor rotation speed signal, and the control circuit 9 receiving the signal of the motor rotation speed R _M The motor rotation speed R _M is compared with the target rotation speed R _O of the hydraulic motor 5, and if there is a difference between the two rotation speeds R _M and R _O , a current signal corresponding to the deviation is sent to the electromagnetic proportional solenoid valve 4.
output to change the swash plate angle of the piston pump 3. As a result, the amount of pressure oil discharged from the pump 3 is changed by a predetermined amount, and the rotation speed of the hydraulic motor 5 is corrected to the target rotation speed. That is, the piston pump 3 is feedback-controlled according to the rotational speed of the hydraulic motor 5, and closed-loop control is performed.

On the other hand, the engine rotation speed R _E at that time is detected by the engine rotation speed sensor 7 and inputted to the control circuit 9 as an engine rotation _speed signal. The deviation signal between the motor rotation speed R _M and the target rotation speed R _O is corrected according to the engine rotation speed. That is, the piston pump 3, which is under feedback control,
Feed forward control is also performed according to R _E.
With this feed forward control, engine 1
When the rotation of piston pump 3 suddenly fluctuates,
The swash plate angle of the pump 3 is rapidly changed and controlled so that it is inversely proportional to changes in the engine speed, and the amount of pressure oil discharged from the pump 3 becomes approximately constant. As a result of the above, the hydraulic motor 5 rotates at a constant speed regardless of rotational fluctuations of the engine 1.

Therefore, in this way, the operation of the piston pump 3 is controlled in a closed loop, and the rotational fluctuations of the engine 1 are also controlled in a feedforward manner, so that the operation of the pump 3 can be controlled with high precision. In addition, it is possible to improve the responsiveness to rotational fluctuations of the engine 1 to compensate for the drawbacks of the closed-loop control, and to perform highly stable control against external disturbances, thereby keeping the rotating drum 2 stable at all times. It can be rotated accurately at a constant speed. Furthermore, this makes it possible to reduce the extra driving loss of the truck mixer vehicle as much as possible, thereby improving driving performance and saving fuel and energy.

In the above embodiment, the swash plate type axial piston pump 3, in which the pressure oil discharge amount changes by changing the swash plate angle, was used as the variable displacement hydraulic pump.
Of course, various types of hydraulic pumps such as variable displacement radial piston pumps and vane pumps may also be used.

Furthermore, it goes without saying that the present invention can be applied not only to the truck mixer vehicle as in the embodiment described above, but also to various vehicles equipped with a rotating body that rotates at a constant speed.

As explained above, according to the present invention, a vehicle is provided in which a variable displacement hydraulic pump is rotationally driven by an engine, and a hydraulic motor is actuated by the pressure oil discharged from the hydraulic pump to rotationally drive a rotating body. In a rotational drive device for a rotating body, the operation of a hydraulic pump is controlled in a feedback manner according to the rotational speed of a hydraulic motor so that the rotating body rotates at a constant speed, and also in accordance with the engine rotational speed. By doing so, it is possible to quickly and accurately control the operation of the pump in response to fluctuations in engine rotation, increasing the stability of the control system against external disturbances, thereby improving the quality of products such as concrete and the driving performance of vehicles. , can effectively contribute to energy saving, etc.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall schematic explanatory diagram, and FIG. 2 is a block diagram of a control system. DESCRIPTION OF SYMBOLS 1... Engine, 2... Rotating drum, 3... Swash plate type axial piston pump, 5... Hydraulic motor, 7... Engine rotation speed sensor, 8... Motor rotation speed sensor, 9... Control circuit.

Claims (1)

[Claims] 1: a variable displacement hydraulic pump 3 driven by an engine 1; a hydraulic motor 5 that receives pressure oil from the hydraulic pump 3 to rotationally drive a rotating body 2 installed in a vehicle; and an engine. an engine rotation speed sensor 7 that detects the rotation speed; a motor rotation speed sensor 8 that detects the rotation speed of the hydraulic motor 5; and a motor rotation speed detected by the motor rotation speed sensor 8 and a preset target rotation speed. By calculating the deviation between the motor rotation speed and its target rotation speed, by superimposing a value corresponding to the increase/decrease value of the engine rotation speed detected by the engine rotation speed sensor 7 from the reference rotation speed on this deviation, the motor rotation speed and its target rotation speed are determined. The deviation signal from the engine rotation speed sensor 7 is corrected by the output signal from the engine rotation speed sensor 7, and based on this corrected signal, the pressure oil discharge amount of the hydraulic pump 3 is adjusted to maintain the rotation speed of the hydraulic motor 5 at the target rotation speed. 1. A constant speed rotation control device for a rotating body in a vehicle such as a truck mixer vehicle, characterized by comprising a control circuit 9 for controlling.