JP2511470Y2 - Oil pump discharge rate control device for concrete pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an oil pump discharge amount control device for controlling an oil pump discharge amount supplied to a main hydraulic cylinder for operating a concrete cylinder, and particularly to an oil pump discharge pressure. The present invention relates to an oil pump discharge amount control device capable of performing constant horsepower control in relation to.

[Prior Art] Generally, in a concrete pump, two concrete cylinders are alternately reciprocated by two main hydraulic cylinders to alternately suck and discharge concrete in a hopper.

As a hydraulic drive circuit for driving the two main hydraulic cylinders in the concrete pump, two concrete cylinders 3 and 4 are alternately reciprocated to suck and discharge concrete, as shown in an example in FIG. The rod sides of the two main hydraulic cylinders 1 and 2 are connected by a sealed circuit 5, and the head sides of the two main hydraulic cylinders 1 and 2 are connected to each other via the main pipe lines 6 and 7. By connecting to the pump 8 to form a closed circuit and changing the tilting direction of the tilting oil pumps 8 driven by the motor 9, pressure oil is sent to the main pipeline 6 side or 7 side, and the main hydraulic cylinder 1, The 2 is reciprocated. The tilting switching of the both tilting oil pumps is performed by the servo valve 11 switched by the pressure oil from the auxiliary pump 10 and the actuator 12 switched by the servo valve 11. That is, after reducing the pressure oil from the auxiliary pump 10 with the pressure reducing valve 13,
The servo valve 11 is switched through the switching valve 14 to serve as a hydraulic pressure source, and the pressure oil from the auxiliary pump 10 is connected to the pipeline.
The tilting direction of the both tilting oil pumps 8 is changed by changing the flow direction of the pressure oil entering the actuators 12 from the servo valve 11 via the servo valve 11 and the main hydraulic cylinders 1, 2 The pressure oil reciprocates between the two, and at this time, the tilt amount (tilt angle) is changed in proportion to the pressure decompressed by the pressure reducing valve 13, and the speed of tilt switching is the same as that of the switching valve 14. It can be changed by a flow rate adjusting valve 17 with the tank 16.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional hydraulic circuit, since the tilting angle of the both tilting oil pumps 8 is determined by the pressure reducing valve 13, it is possible to correspond to the pressure preset by the pressure reducing valve 13. The tilt angle is changed, and the discharge amount from both tilt oil pumps 8 is also determined by this tilt angle. Is it true that the tilt angle of both tilt oil pumps 8 is the target tilt angle? Since it has not been conventionally confirmed whether or not the operation is performed under the assumption that the tilt angle is the set value and the target discharge amount is achieved. Therefore, in actuality, the target discharge amount may not be reached, and in such a case, the discharge amount of the concrete may be insufficient due to the small amount of pressure oil supplied to the main hydraulic cylinder 1 or 2. . Further, in the conventional method, the servo valve 11 is not controlled to switch the tilting of the both tilting oil pumps 8 even if the pressures of the main pipe lines 6 and 7, that is, the discharge pressure becomes high.
The constant horsepower control, which is performed by decreasing or increasing the discharge flow rate when the discharge pressure becomes high or low, has not been performed.

Therefore, in the present invention, when the tilting angle of both tilting oil pumps is operated to a certain angle by the servo valve, it is checked whether the tilting angle is actually that angle, and the target discharge from the both tilting oil pumps is always checked. It is intended that the amount be discharged and that constant horsepower control be performed.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention connects two tilting oil pumps to two main hydraulic cylinders for operating two concrete cylinders via a main pipe, In a configuration in which pressure oil is alternately supplied to both main hydraulic cylinders by switching tilting of both tilting oil pumps, a servo valve for switching tilting of both tilting oil pumps is provided with an operation lever of the operation lever. The value from the differential transformer that detects the actual tilting position of the both tilting oil pumps is compared with the value of the preset tilting amount so that the difference can be adjusted by adjusting the output from the potentiometer output by operation. If there is, a comparison calculator for outputting a correction signal to the servo valve to correct the value actually detected to a preset target value is provided with a line connecting the potentiometer and the servo valve. It is installed in the middle of the engine so that the tilt position of the oil pump can be fed back to the servo valve by a differential transformer.
A pressure switch for detecting the discharge pressure of both tilting oil pumps is provided, and the pressure switch and the servo valve are connected so as to control the servo position to the limited tilting position determined by the pressure switch.

[Operation] When the operation lever is operated by predetermining how much the operation lever should be tilted to achieve the discharge amount, the servo valve operates according to the output of the potentiometer, and the tilting direction of the bi-tilt oil pump is changed. The tilt angle can be changed. As a result, a predetermined amount of oil is supplied from both tilt oil pumps to either of the two main hydraulic cylinders. At this time, the actual tilt angle of both tilt oil pumps is detected by the differential transformer. Is fed back to the servo valve, the tilt angle detected by the differential transformer is compared with the tilt angle determined by the operation of the operating lever, and correction is performed to obtain the initially targeted value. Done. Further, the discharge pressure at this time is detected by the pressure switch, and when the pressure is abnormally high, it is controlled so as to reduce the tilt angle and decrease the discharge flow rate, so that constant horsepower control is performed. Become.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which two concrete cylinders 3 and 4 are alternately reciprocated by two main hydraulic cylinders 1 and 2, and the main hydraulic cylinder 1
And 2 are connected to each other by a sealed circuit 5 and the head sides of the main hydraulic cylinders 1 and 2 are connected to both tilting oil pumps 8 through main pipes 6 and 7, respectively. The pressure oil is alternately supplied to the head side of the main hydraulic cylinder 1 or 2 by switching the tilt direction of the tilt hydraulic pump to the positive side or the negative side, and the tilt angle of both tilt oil pumps 8 is changed. As described above, the discharge flow rate can be increased or decreased as in the conventional case. The oil pump discharge amount control device of the present invention is an actuator (rocker cam) 18 for changing the tilting direction and tilting angle of the both tilting oil pumps 8.
Is operated by a servo valve (proportional solenoid valve) 19. The servo valve 19 outputs an output from the potentiometer 21 when the operating lever 20 with the potentiometer 21 is operated at an arbitrary angle from the minimum position to the maximum position. The tilting angle of the tilting oil pump 8 can be adjusted by adjusting the tilting angle of the tilting oil pump 8. The amount of the discharge amount is set in advance, and the operation lever 20 may be operated so as to obtain the tilt angle at which the target discharge amount is obtained.

Further, a differential transformer 23 for detecting the actual tilting position of the both tilting oil pumps 8 is provided, and the differential transformer 23 is provided.
If there is a difference by comparing the value from the above and the value of the preset tilt amount, the comparison calculator 24 for outputting a correction signal for correcting the actually detected value to the preset target value to the servo valve 19. Is provided in the middle of a connection line 25 between the potentiometer 21 and the servo valve 19, and the comparison calculator 24 and the differential transformer 23 are connected to each other so that the actual tilting positions of the both tilting oil pumps 8 are different from each other. The dynamic transformer 23 provides feedback to the servo valve 19. In addition, two main hydraulic cylinders
In order to perform constant horsepower control in supplying pressure oil to 1, 2, a pressure switch 27 is connected between both main pipelines 6, 7 via a shuttle valve 26, and the pressure switch 27 is connected to a servo valve 19 To control the servo position to the limit tilt position determined by the pressure switch 27.

Now, when the operation lever 20 is operated to set the tilting direction of both tilting oil pumps 8 to the plus side via the servo valve 19, pressure oil is discharged from both tilting oil pumps 8 to the main pipeline 6 side, and tilting oil pump 8 is tilted. It is assumed that the pressure oil is discharged to the main pipe line 7 side when the rolling direction is set to the negative side, and the operating lever 20 is tilted, for example, 15 degrees, so that the discharge flow rate becomes 80 m ³ / h. Assuming that the tilting position (tilt angle) of the oil transfer pump 8 is set so that when the target flow rate of 80 m ³ / h is to be discharged to the main pipeline 6 side (plus side), , Operating lever 20
Incline 15 degrees. At this time, both tilting oil pump 8
Is detected by the differential transformer 23, the value is input to the comparison calculator 24, and the actual tilt angle detected by the differential transformer 23 and the discharge amount of 80 m ³ / h are targeted. The value of the tilt angle set for this purpose is compared by a comparison calculator, and there is a difference between the two. For example, the tilt angle detected by the differential transformer 23 corresponds to the discharge flow rate of 75 m ³ / h. If it is, the correction command for correcting the tilting angle so that the target discharge flow rate is 80 m ³ / h is sent to the servo valve 19, and the tilting of the both tilting oil pumps 8 is corrected. It When the preset value so that the target discharge flow rate is obtained and the actual value are different from each other, the target discharge flow rate is corrected so that the main hydraulic cylinder 1 or An appropriate amount of pressure oil is supplied to 2 to ensure proper operation of the concrete pump. Further, in the present invention, between the main pipelines 6 and 7,
Since there is a pressure switch 27 for constant horsepower control, and the servo position can be controlled to the limited tilting position determined by the pressure switch 27, the two tilting oil pump 8
To the positive side or the negative side to switch the main line 6 or 7
When the pressure oil is discharged to the main pipe line 6 or 7, that is, when the discharge pressure of the oil pump 8 is low, the tilt angle of the oil pump 8 is increased to increase the discharge flow rate.
Alternatively, when the discharge pressure to 7 becomes high and the pressure switch 27 is activated, the tilt angle of the oil pump 8 is made small and the discharge flow rate is reduced. As a result, the discharge amount can be changed by the pump discharge pressure on both the positive side and the negative side, and the characteristic curve I shown in FIG. 2 can be controlled so as to be always constant.

[Effects of the Invention] As described above, according to the oil pump discharge rate control device of the present invention, when the operation lever with the potentiometer is operated, the tilt of the oil pump is adjusted by the servo valve with respect to the output of the potentiometer. In addition, the differential transformer detects the actual tilt position when operated with a preset value, and the actual tilt angle value detected by the differential transformer and the preset tilt angle are detected. The value of the turning angle is compared with the comparison calculator, and a correction signal that corrects the value actually detected if there is a difference between the two is output to the servo valve to reach the target discharge flow rate. Further, a pressure switch for detecting the discharge pressure of the oil pump is provided in the main pipe line, and the pressure switch and the servo valve are connected so as to control the servo position to the limited tilt position determined by the pressure switch. Since it is configured as such, it is possible to always discharge a target amount of pressure oil and operate the cocrete pump properly, and it is possible to perform constant horsepower control operation of the oil pump and not to use a high-power prime mover. And so on.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention, FIG. 2 is a pump discharge pressure-discharge amount characteristic diagram obtained by the present invention, and FIG. 3 is a schematic view showing a conventional example. 1,2 ... Main hydraulic cylinder, 6,7 ... Main pipeline, 8 ... Tilting oil pump, 19 ... Servo valve, 20 ... Operating lever, 21 ... Potentiometer, 23 ... Differential transformer, 24 ... Comparison calculator, 25 … Connection line, 27… Pressure switch.

Claims (1)

(57) [Scope of utility model registration request] 1. A tilting oil pump is connected to two main hydraulic cylinders for operating two concrete cylinders via a main pipe, and the tilting direction and tilting amount of the oil pump are changed by a servo valve. In the oil pump discharge rate control device for the concrete pump, the potentiometer and the servo valve are connected so as to adjust the tilt of the oil pump in accordance with the output of the potentiometer attached to the operating lever, and the oil The value from the differential transformer that detects the actual tilt position of the pump is compared with the value of the preset tilt amount, and if there is a difference, a correction signal that corrects the actually detected value to the preset target value is sent. A comparison calculator for outputting to the servo valve is installed in the middle of the line connecting the potentiometer and the servo valve, and the tilting position of the oil pump is changed to the differential transformer. And a pressure switch for detecting the discharge pressure of the oil pump is provided in the main pipe line to control the servo position to the limit tilt position determined by the pressure switch. An oil pump discharge amount control device for a concrete pump, comprising a switch and a servo valve connected to each other.