KR100319933B1 - Load compensator of hydraulic elevator - Google Patents

Abstract

The present invention relates to a load compensation device of a hydraulic elevator. Conventionally, by using a sensor such as a cylinder pressure detector and a pump pressure detector inside the control valve, it is difficult to accurately adjust the outputs of the two sensors, and the output value is different from the initial setting value, which requires periodic inspection. In addition, there is a problem that the price is high, resulting in a cost increase and a decrease in the reliability of the product. Therefore, the present invention is a hydraulic elevator of the method of controlling the rotational speed of the induction motor driving the hydraulic pump to control the discharge flow rate of the hydraulic pump, the hydraulic cylinder side chamber and the hydraulic pump side chamber is formed in the valve block, When the hydraulic cylinder side rod and the hydraulic pump side rod are connected to each other with elastic springs, and the hydraulic cylinder side pressure and the hydraulic pump side discharge pressure coincide, the hydraulic pressure area of the hydraulic pump side exhaust chamber becomes larger than the hydraulic cylinder side pressure area. A load detection valve formed of a structure in which the movement of the spool changes abruptly; By providing a load compensation detection switch operated by the movement of the load on the hydraulic pump side of the load detection valve, it is possible not only to perform more accurate load compensation, but also to reduce the cost and improve the reliability of the product by not using expensive sensors. It can be effected.

Description

Load compensator of hydraulic elevator

The present invention relates to a load compensation device of a hydraulic elevator.

In general, the hydraulic cylinder for moving the hydraulic elevator in the vertical direction is to change the pressure in the hydraulic cylinder according to the weight of the car and the number of people (including cargo) in the car, the main control valve of the hydraulic elevator by the inverter control method. Consists of a check valve actuated by pilot operating pressure. The main control valve acts as a check valve at the time of ascending and supplies the hydraulic oil discharged from the hydraulic pump to the hydraulic cylinder, and at the time of descending, the check valve is forcibly opened by the pilot pressure to pressurize the hydraulic oil in the hydraulic cylinder through the check valve. It flows to the pump side. In the inverter control valve configured as described above, the hydraulic oil always passes through the check valve during the rising or falling, and at this time, the flow rate is a method of directly controlling the discharge flow rate of the hydraulic pump by controlling the speed of the induction motor. Depending on the pilot pressure, only two functions can be performed, either fully closed or fully open. Therefore, in order to move the car of the hydraulic elevator, the hydraulic pump is driven to operate the check valve while the pressures of the check valve's input and output ports are the same, and then the speed of the hydraulic pump must be decreased or decreased so that the car can run normally. Referred to as "load compensation" in hydraulic elevators.

The present invention relates to a load compensating device of such a hydraulic elevator, and in particular, by comparing the discharge pressure of the hydraulic cylinder and the hydraulic pump by a mechanical method and outputs a signal when the two pressures are the same, this output signal is a speed command generator of the car It relates to a load compensator used as a start signal of.

The hydraulic elevator is generally a car (1) in which a passenger boards or loads, as shown in Figure 1, and a hydraulic cylinder (2) for generating a driving force hydraulically to drive the car (1) on a hoistway; In order to lift and lower the car 1 by the driving force by the hydraulic cylinder 2, one end is fixed to the ground through the pulley 2B installed on the ram 2A of the hydraulic cylinder 2 and the other end is The main rope 3 fixed to (1) and a speed governor installed on the upper side of the hoistway as a safety device and connected by the lower side Weiihgt pulley 5 and the rope 6 are provided. It is installed. In addition, an operation control device 7, a speed control device 8, and an inverter 9 are provided for the operation control of the elevator by the hydraulic cylinder 2, and the hydraulic tank 10 or the The control valve 11 is installed to open and close the oil supply from the hydraulic tank 10 to the hydraulic cylinder 2 side. At the same time, as a means for discharging oil in the hydraulic tank 10 to the hydraulic cylinder 2 side, a hydraulic pump 12 is provided in the pipe 15 between the hydraulic tank 10 and the control valve 11. The hydraulic pump 12 is driven by the induction motor 13, and the induction motor 13 is configured to be operated by the inverter 9 for generating three-phase alternating current of variable voltage variable frequency. . In addition, rotary encoders 14 and 14A are installed in the weight pulley 5 and the induction motor 13, respectively, for speed detection, and the rotary encoders 14 and 14A and the control valve 11 are respectively installed. The signal output from is configured to be input to the speed control device (8). The hydraulic cylinder 2 and the control valve 11, the control valve 11 and the hydraulic tank 10 are connected to the pipe 15, respectively, and the control valve 11 is connected to the voltage 111A and 111B. It operates by the command of the operation control apparatus 7 by this. The control valve 11 is in series with the opening solenoid valve 11 and the opening solenoid valve 11 which is maintained in the normally closed state and is converted into the open state by the voltage 111A applied by the operation control device 7. And the solenoid valve 112 for closing and being kept in the normally open state and being converted to the closed state with the voltage 111B applied by the operation control device 7, the opening solenoid valve 11 and the closing solenoid valve ( The pilot operated main shock valve 113 is branched from the pilot pipe 112 between the 112 and connected to the pilot pipe 112 connected from the hydraulic pump side port 11B to the hydraulic cylinder side port 11B. Is installed on the front and rear pilot pipe 112 in the center of the pilot operated main shock valve 113, and detects the hydraulic cylinder pressure signal (114A) or the hydraulic pump side pressure signal (115A) speed control device (8) send to It consists of a cylinder-side pressure detector 114 and the pump-side pressure detector 115. Reference numeral 116 denotes a relief valve, and 117 denotes a check valve for preventing cavitation.

In the hydraulic elevator configured as described above, first, when an operation command of the car 1 is generated in the operation control device 7, the speed control device 8 detects the pressure signal 114A of the cylinder-side pressure detector 114 and generates it. The reference pressure is generated as a reference signal, and the inverter 9 generates three-phase alternating current of a variable voltage variable frequency using the pressure signal 115A of the pump side pressure detector 115 as a feedback signal. (13) is driven. At this time, when the discharge pressure of the hydraulic pump 12 connected to the induction motor 13 by the drive of the induction motor 13 is equal to the pressure on the cylinder side, the operating solenoid 7 to maintain the normally closed state in the operation control device 7 Voltages 111A and 111B are sequentially applied to the valve 11 and the closing solenoid valve 112 to maintain the normally open state, thereby maintaining the pilot operated main shock valve 113 in the open state. At the same time, the speed control device 8 is commanded to generate a speed command, and the speed signal 1A of the car 1 and the speed signal 13A of the induction motor 13 are controlled by a feedback signal. The car 1 is raised or lowered. When the car 1 reaches the stationary floor, the driving control device 7 again turns off the opening solenoid valve 11 and the closing solenoid valve 112 to return to the original state, that is, the opening solenoid valve ( 11) from the open state to the normally closed state again, the closing solenoid valve 112 is switched from the closed state to the normally open state to maintain the pilot operated main shock valve 113 in the closed state, thereby The oil 1 on the hydraulic cylinder 2 side is prevented from flowing to the hydraulic tank 10 side to completely stop the car 1.

However, such a conventional hydraulic elevator detects the pressure on the cylinder side and sets it as the reference pressure signal, and the pressure on the hydraulic pump side to compensate for the load by the two pressure sensors that perform the load compensation by controlling the feedback signal pressure. First, since the general pressure sensor is an analog detection method that detects pressure with a strain gauge, a piezoelectric element, etc., there is a difference in the output signal of each sensor, and the gain of the amplifier amplifying the sensor output. (Gain) is also slightly different, so it is very difficult to accurately adjust the outputs of the two sensors, there was a problem that the control accuracy is lowered by the output difference of the two sensors. Second, the pressure sensor generally has hysteresis characteristics, and the hydraulic cylinder pressure sensor always receives the pressure corresponding to the weight of the car at no load. Therefore, when it is used for a long time, the initial zero point by the permanent change of the sensor is used. There was a problem in that an offset occurred and the output value was different from the initial set value, requiring periodic inspection. Third, there is a problem that the price is expensive due to the need for the sensor and the peripheral hardware by using a pressure detector.

Therefore, an object of the present invention is to enable a more accurate load compensation while the cost is low in mechanical operation.

1 is a schematic configuration diagram of a general hydraulic elevator.

2 is a hydraulic circuit diagram of a conventional control valve.

3 is a hydraulic circuit diagram of a control valve of the present invention.

4A, 4B, and 4C show an operation state of the load compensation device of the present invention.

4A is an operation state diagram when stopped.

4B is an operation state diagram at the time of load compensation.

4C is an operation state diagram when the load compensation is completed.

** description of the symbols for the main parts of the drawings **

120: control valve 120A: hydraulic cylinder side port

120B: Hydraulic pump side port 121: Open solenoid valve

122: closing solenoid valve 123: pilot pipe

124: pilot operated main check valve 125: normal closed valve

130: Load detection device 130A: Load detection valve

130B: Normal closed switch 130C: Contact

131: valve block 131A: through hole

131B: Seal 131C, D, E: 1st, 2nd, 3rd pilot tube

132: hydraulic cylinder side exhaust chamber 133, 134: hydraulic pump side 1, 2 exhaust chamber

135: spool 136: hydraulic cylinder side rod

137: hydraulic pump side rod 138, 139: spring

In order to achieve the object of the present invention, in the hydraulic elevator system of controlling the discharge flow rate of the hydraulic pump by controlling the rotational speed of the induction motor for driving the hydraulic pump, the hydraulic cylinder side chamber and the hydraulic pump side chamber in the valve block When the hydraulic cylinder side rod and the hydraulic pump side rod are connected to each other and the spool is elastically supported by a spring, and the hydraulic cylinder side pressure and the hydraulic pump side discharge pressure match, the hydraulic pressure area of the hydraulic pump side exhaust chamber is the hydraulic cylinder side. A load detection valve formed to have a structure larger than the hydraulic pressure area so that the movement of the spool changes rapidly; Provided is a load compensation device for a hydraulic elevator, characterized by comprising a load compensation detection switch operated by the movement of the load on the hydraulic pump side of the load detection valve.

The drive signal and the speed command signal of the control valve may be operated according to the contact signal of the load compensation detection switch.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

Figure 3 is a hydraulic circuit diagram of the control valve of the present invention, Figures 4a, 4b, 4c shows the operating state of the load compensation device of the present invention, the control valve 120 is normally closed as usual The solenoid valve 121 for opening is converted into the open state by the voltage 121A applied by the operation control device 7 and the opening solenoid valve 121 is connected in series with the open solenoid valve 121 to maintain the open state at all times. Branch from the closing solenoid valve 122 which is converted to the closed state by the voltage 122A applied by the apparatus 7 and the pilot tube 123 between the opening solenoid valve 121 and the closing solenoid valve 122. And a pilot operated main check valve 124 installed in the pilot pipe 123 connected from the hydraulic pump side port 120B to the hydraulic cylinder side port 120A, and a lily for maintaining the pressure in the circuit at a set value. If It consists of a bracket 126, and a cavitation preventing check valve (127).

In the control valve of such a hydraulic elevator, the present invention branches from the hydraulic pump side port 120B to the hydraulic cylinder side port 120A side of the pilot pipe 123 connected to the check valve 127 side as shown in FIG. 3. In this regard, the pilot pipe 123 is connected to the pilot operated main shock valve 124 side, and the pressure port is provided at the normal position, that is, the valve position when the operating force is not applied to the pilot pipe 123. A normal close valve 125 is installed to maintain a closed state, and a load detection device 130 is installed at the front side of the normal closed valve 125. In addition, the load detection device 130 is a load detection switch on one side of the load detection valve 130A, as shown in Figure 4a, 4b, 4c, the normal closed switch (130B) is installed, The signal output from the normal closed switch 130B is input to the operation control device 7 and configured to control the operation of the hydraulic elevator according to the input signal.

The load detection valve 130A includes a hydraulic cylinder side exhaust chamber 132, a hydraulic pump side first exhaust chamber 133, and a second exhaust chamber 134 inside a valve block 131 constituting a body. The hydraulic pump side second discharge chamber 134 is provided with a spool 135. In addition, the hydraulic cylinder side rod 136 and the hydraulic pump side rod 137 are integrally provided on both sides of the spool 135, and the hydraulic cylinder side rod 136 and the hydraulic pump side rod 137 are respectively springs ( 138, 139 is elastically supported. The hydraulic cylinder side rod 136 and the hydraulic pump side rod 137 are provided at both sides of the valve block 131 at the hydraulic cylinder side exhaust chamber 132 and the hydraulic pump side first exhaust chamber 133 inside the valve block 131. And a through hole 131A through which the hydraulic cylinder side rod 136 and the hydraulic pump side rod 137 pass through the second exhaust chamber 134 so that the linear reciprocating motion is possible, and the through hole 131A is sealed. It is sealed by (Seal) 131B. In addition, the contact 130C of the normal closed switch 130B provided at one side of the load detection valve 130A is turned on / off by the operation of the hydraulic pump side rod 137 of the load detection valve 130A. It works. In addition, the discharge detection pressure of the first pilot pipe 13C and the hydraulic pump 12 for supplying the pressure of the hydraulic cylinder 2 to the hydraulic cylinder side exhaust chamber 132 of the valve block 131 is provided to the load detection valve 130A. The second pilot pipe 13D to supply the hydraulic pump side first exhaust chamber 133 of the valve block 131, and the pressure of the hydraulic tank 10 to the hydraulic pump side second exhaust chamber 134 of the valve block 131. The third pilot pipe 131E to be supplied is connected.

The following describes the operating state of the present invention configured as described above.

First, each of the hydraulic pressure areas of the load detection valve 130A of the load detection device 130 has the following relationship.

A1 = A2

A1 <A2 + A3

Here, A1 is the hydraulic pressure area of the hydraulic cylinder side exhaust chamber 132.

A2 is the hydraulic pressure area of the first drain chamber 133 on the hydraulic pump side.

A3 is the hydraulic pressure area of the second exhaust chamber 134 on the hydraulic pump side.

to be.

First, at the time of stop, the pressure on the hydraulic cylinder 2 side is cut off by the normal closed valve 125, and the hydraulic pump 12 does not operate. In addition, due to the gap between the spool 135 and the valve block 131 of the load detection valve 130A, all the pressures of the exhaust chambers 132, 133 and 134 are brought to atmospheric pressure, and the spool 135 is a spring. The spool 135 is positioned as shown in FIG. 4A because it is in equilibrium by 138 and 139. When the operation command occurs in the operation control device 7, when the normal closed valve 125 is turned on at the same time as the operation command, the pressure on the hydraulic cylinder 2 side becomes the hydraulic cylinder of the load detection valve 130A. Since the discharge pressure of the hydraulic pump 12 is not generated because it is supplied to the side exhaust chamber 132, the first and second exhaust chambers 133 and 133 of the hydraulic pump side become atmospheric pressure, and the pressure of the hydraulic cylinder 2 side is P1. The force pushing the spool 135 is

A1 * P1> 0

As a result, the spool 135 of the load detector 130 moves toward the hydraulic pump side exhaust chambers 133 and 134 as shown in FIG. 4B. In addition, the hydraulic pump side rod 137 is moved by the movement of the spool 135 to turn off the contact 130C of the normal closed switch 130B.

Simultaneously with the operation command, the speed control device 8 generates three-phase alternating current of variable voltage variable frequency in the inverter 9 through an open control so that the output torque of the induction motor 13 increases at a constant rate. Thus, the induction motor 13 is driven, and the discharge pressure of the hydraulic pump 12 connected to the induction motor 13 continues to increase. In addition, the discharge pressure is supplied to the hydraulic pump side first exhaust chamber 133 through the pilot pipe 112, wherein the hydraulic pump side second exhaust chamber 134 is connected to the hydraulic tank 10 through the throttling valve 128. Thus, the atmospheric pressure is maintained. Therefore, if the hydraulic cylinder pressure is P1 and the discharge pressure of the hydraulic pump is P2, the force pushing the spool 135 is

A1 * P1 ＞ A2 * P2

Becomes That is, the discharge pressure P2 of the hydraulic pump must be equal to the load pressure P1 of the hydraulic cylinder in order to achieve a balanced state.

When the hydraulic cylinder side discharge pressure P1 becomes equal to the discharge pressure P2 of the hydraulic pump, and the spool 135 is slightly pushed toward the hydraulic cylinder 2 side, the pressure of the hydraulic pump side second exhaust chamber 134 becomes the hydraulic pump side first exhaust chamber ( Since the pressure of the hydraulic cylinder side is P1 and the discharge pressure of the hydraulic pump is P2,

A1 * P1 <A2 * P2 + A3 * P2 (P1 = P2)

Becomes Therefore, the spool 135 of the load detection device 130 moves to the hydraulic cylinder side exhaust chamber 132 side as shown in Fig. 4c, and the hydraulic pump side rod 137 moves normal by the movement of the spool 135. The contact of the closed switch 130B is to be turned on.

The contact signal of the normal closed switch (130B) is transmitted to the operation control device (7), wherein if the signal transmitted to the operation control device (7) (on), the solenoid valve for opening as in the prior art The solenoid valve 121 for opening and closing the solenoid valve 121 which maintains a normally closed state by sequentially applying voltages 121A and 121B to the 121 and the closing solenoid valve 122 is always closed. The valve 122 is switched to the closed state to maintain the pilot operated main shock valve 124 in the open state. At the same time, the speed control device 8 is commanded to generate a speed command, and the speed is controlled using the speed signal 1A of the car 1 and the speed signal 13A of the induction motor 13 as feedback signals. While the car (1) is to be raised or lowered. When the car 1 reaches the stationary floor, the operation control device 7 turns off the opening solenoid valve 121 and the closing solenoid valve 122 to return to the original state, that is, the opening solenoid valve ( 121 is changed from the open state to the closed state, and the closing solenoid valve is switched from the closed state to the open state, respectively, to maintain the pilot operated main shock valve 124 in the closed state. By blocking the flow of hydraulic oil from the cylinder 2 to the hydraulic tank 10 side, the car 1 can be completely stopped.

As described above, the present invention mechanically performs load detection to generate the speed command of the car according to the load detection signal, thereby not only providing accurate load compensation, but also reducing the cost and improving reliability of the product by not using expensive sensors. It can be effected.

Claims (2)

In a hydraulic elevator in which a rotational speed of an induction motor for driving a hydraulic pump is controlled to control the discharge flow rate of the hydraulic pump, a hydraulic cylinder side chamber and a hydraulic pump side chamber are formed in the valve block, and both sides have hydraulic pressure inside. When the spool connected to the cylinder side rod and the hydraulic pump side rod is elastically supported by the spring, and the hydraulic cylinder side pressure and the hydraulic pump side discharge pressure coincide, the hydraulic pressure area of the hydraulic pump side exhaust chamber becomes larger than the hydraulic cylinder side hydraulic pressure area, and the spool movement A load detection valve formed of a rapidly changing structure; And a load compensation detection switch operated by movement of the load on the hydraulic pump side of the load detection valve. The load compensating device of a hydraulic elevator according to claim 1, wherein a drive signal and a speed command signal of a control valve are operated according to a contact signal of the load compensation detection switch.