Patent Grant
8051653
1. Technical Field
The present disclosure relates to control apparatuses, and particularly to a control apparatus for controlling motor velocity and hydraulic pump pressure of a hydraulic machine.
2. Description of Related Art
Hydraulic machines, such as hydraulic injection molding machines, are operated by hydraulic pumps controlled by motors. Motor velocity and hydraulic pump pressure are controlled by a control apparatus to make moveable elements of the injection molding machine work. Generally, product engineers manually adjust velocity and pressure according to experience, which may not be accurate and is inconvenient.
What is needed is to provide a velocity-pressure control apparatus of a hydraulic machine to overcome the above-described shortcomings.
Referring to
The velocity-pressure switch module 10 includes a pressure command generator 11, a first comparison unit 12, a pressure controller 13, a velocity limiter 14, a velocity command generator 15, a switch such as a relay 16, a comparator 17, and a second comparison unit 18. In one embodiment, the relay 16 includes a single-pole double-throw (SPDT) switch K, and a control terminal to control the SPDT switch K. The SPDT switch K includes a first throw 1, a second throw 2, and a pole 3.
The pressure command generator 11 is configured for outputting a target pressure signal of the oil pump 60, and giving a desired pressure of the oil pump 60 to a positive terminal A of the first comparison unit 12. The pressure sensor 30 senses current pressure of the oil pump 60 and transmits a pressure sensing signal relaying the current pressure to a negative terminal B of the first comparison unit 12. The first comparison unit 12 outputs a pressure compensation signal via an output C, by subtracting the pressure sensing signal from the target pressure signal and sending the pressure compensation signal to an input of the pressure controller 13 and an input of the comparator 17.
The pressure controller 13 receives the pressure compensation signal and obtains a compensation velocity according to the pressure compensation signal, and then correspondingly outputs a compensation velocity signal to an input of the velocity limiter 14. The comparator 17 receives the pressure compensation signal. When the pressure compensation signal is a positive signal or a null signal, namely the current pressure of the oil pump 60 is less than or equal to the expectation pressure, the comparator 17 outputs a velocity control signal to the control terminal of the switch K to control the switch K to connect the pole 3 to the first throw 1. When the pressure compensation signal is a negative signal, namely the current pressure of the oil pump 60 is greater than the desired pressure, the comparator 17 outputs a pressure control signal to the control terminal of the switch K, to control the switch K to connect the pole 3 to the second throw 2.
The velocity command generator 15 is configured for outputting a predetermined velocity signal, giving a predetermined velocity, to the velocity limiter 14. An output of the velocity limiter 14 is connected to the second throw 2 of the switch K. The velocity limiter 14 compares the compensation velocity signal with the predetermined velocity signal, and outputs the smaller velocity signal as a limiting velocity command signal. The velocity command generator 15 is also configured for outputting a target velocity signal, giving a desired velocity to the first throw 1 of the switch K. When the pole 3 is connected to the second throw 2 of the switch K, the limiting velocity command signal is output to a positive terminal A of the second comparison unit 18. When the pole 3 is connected to the first throw 1 of the switch K, the target velocity signal is output to the positive terminal A of the second comparison unit 18.
The motor driver 20 includes a velocity controller 22 and a current limiter 24. The velocity sensor 40 senses a current velocity of the motor 50 and transmits a corresponding velocity sensing signal to a negative terminal B of the second comparison unit 18. The second comparison unit 18 outputs a velocity compensation signal via an output C, by subtracting the velocity sensing signal from the target velocity signal and sending the velocity compensation signal to an input of the velocity controller 22. The velocity controller 22 processes the velocity compensation signal and then drives the motor 50 via the current limiter 24.
In use, the velocity-pressure control apparatus works at a velocity control mode at first, wherein the pole 3 is connected to the first throw 1 of the switch K. At this time, the motor driver 20 receives the velocity compensation signal from the second comparison unit 18, so as to control acceleration of the motor 50 such that the pressure of the oil pump 60 increases. At the same time, the comparator 17 receives the pressure compensation signal from the first comparison unit 12. If the pressure compensation signal is a positive signal or a null signal, the velocity-pressure control apparatus continues to work at the velocity control mode. If the pressure compensation signal is a negative signal, the comparator 17 outputs the pressure control signal to control the switch K to connect the pole 3 to the second throw 2. The motor driver 20 receives the velocity compensation signal from the second comparison unit 18, so as to control deceleration of the motor 50 such that the pressure of the oil pump 60 decreases. Therefore, the velocity-pressure control apparatus works at a master pressure control and slave velocity control mode.
Because the motor 50 and the oil pump 60 works at the velocity control mode when the pressure of the oil pump 60 increases, the motor 50 is rotated at a very fast velocity in this period, which can reduce time for increasing the pressure of the oil pump 60. Because the motor 50 and the oil pump 60 works at the master pressure control and slave velocity control mode when the pressure is reduced, the velocity of the rotation of the motor 50 can be limited, which can avoid shaking of the hydraulic machine.
It is to be understood, however, that even though numerous characteristics and advantages of the present disclosure have been set forth in the foregoing description, together with details of the structure and function of the disclosure, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008 1 0305683 | Nov 2008 | CN | national |
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| Number | Date | Country | |
|---|---|---|---|
| 20100126162 A1 | May 2010 | US |
