Control device

[Detailed Description of the Invention]

[Industrial Application]

This invention relates to the control device of 3 port valves with which speed can make an actuator rise from the state of zero (0) to target speed other than zero quickly.

[Description of the Prior Art]

Before, as control of the oil pressure cylinder by 3 port servovalve is shown in Drawing 3, it is performed. That is, speed sensor 2 detected the speed of oil pressure cylinder l placed horizontally, and it has inputted velocity feedback signal F and target speed T from this speed sensor 2 into control device 3. And a control signal is inputted into 3 port servovalve 5 from this control device 3, and the port by the side of the head of oil pressure cylinder l is switched to pressure source 6 and tank 7, and it connects, and is controlling the operation of oil pressure cylinder l by the operation of this 3 port servovalve. At this time, 3 port servovalve 8 was located in Nonpol position S2, was open for free passage on tank 7, and has opened wide the port by the side of the rod of oil pressure cylinder l on the tank. And as shown in Drawing 4, the above-mentioned control device 3 consists of integration element 11 and subtraction circuit 12, and is target speed T, Ask for a deviation with velocity feedback signal F outputted from speed sensor 2 in subtraction circuit 12, integrate integration element 11 with the deviation outputted from this subtraction circuit 12, it is made not to produce a remains deviation, a control signal is outputted to 3 port servovalve 5, and the speed of oil pressure cylinder I is controlled.

[Problem(s) to be Solved by the Invention]

However, although speed sensor 2 has offset and cylinder l has stopped at the above-mentioned conventional control device 3, when the positive signal is being outputted, When target speed T is 0, a negative deviation signal is outputted from subtraction circuit 12, and integration element 11 outputs the signal which integrates with this negative deviation and increases to negative one. Therefore, 3 port servovalve 5 of Drawing 3 is neutral position S. also depending -- time until the negative electric charge stored in integration element 11 when a spool was made shifted in the direction of symbol position S, too much and then target speed T other than zero was inputted changes to a positive electric charge, Time until the spool of 3 port servovalve 5 shifts to symbol position S0 and also symbol position S1 from the state remarkably shifted in the symbol position St direction is taken, time until speed rises from the state of O to target speed other than zero becomes long, and there is a problem that a response is slow. That is, since the output of integration element 11 will be remarkably depressed in the negative direction when offset etc. have speed in speed sensor 2 in the state of 0, when target speed T other than zero is inputted for the speed of oil pressure cylinder l in the state of O, response delay produces it. Then, the object of this invention and the speed of a Is actuator are to make 3 port valves answer quickly and make it not make an actuator produce the delay in a response in the state of 0 when target speed other than zero is inputted.

[Means for Solving the Problem]

3 port valves which the present invention switches a port of an actuator to a pressure source and a tank, and connect in order to achieve the above-mentioned object, A control device controlled based on a velocity feedback signal from a speed sensor which detects speed of the above-mentioned actuator, and a signal showing target speed is characterized by comprising: The 1st subtraction circuit which computes a deviation of a signal showing the above-mentioned target speed, and a velocity feedback signal from the above-mentioned speed sensor, Integration element, An integration initial value output means which outputs an integration initial value corresponding to speed of zero of the above-mentioned actuator, A deviation of an integration initial value outputted from the above-mentioned integration initial value output means and an output of the above-mentioned integration element is computed, A spool position command signal output means which outputs a spool position command signal showing the 2nd subtraction circuit which outputs this deviation to an integration element, and a predetermined bias position where a spool of the above-mentioned 3 port valves carried out the software of the load port to the position side which a tank is made to open for free passage from a neutral position, An addition circuit which outputs a signal which computes the sum of an output of the above-mentioned integration element, and a spool position command signal outputted from the above-mentioned spool position command signal output means, and by which it denotes this sum to the above-mentioned 3 port valves, A switch which controls an input from the above-mentioned 1st subtraction circuit to an integration element of an outputted deviation signal, A switch which controls an input to the above-mentioned integration element of an output from the above-mentioned integration initial value output means, and an output of the above-mentioned integration element, A switch control circuit which responds to whether it is larger than a standard value for an absolute value of the above-mentioned target speed to distinguish zero from a switch which controls an input to the above-mentioned addition circuit of an output from the above-mentioned spool position command signal output means, turns on each above-mentioned switch and carries out OFF control.

[Function]

According to the above-mentioned composition, a switch control circuit compares the standard value for distinguishing 0 with the absolute value of target speed, and controls each above-mentioned switch according to the comparison result. If it will distinguish that target speed is 0 now supposing the absolute value of the above-mentioned target speed is smaller than the above-mentioned standard value namely, the switch for inputting the output of the 1st subtraction circuit into an integration element serves as OFF, the 1st subtraction circuit and an integration element will be separated and other switches will be set to ON. Therefore, the deviation of the integration initial value which expresses the speed of 0 from an integration initial value output means, and the output from an integration element is outputted to the 2nd subtraction circuit, and the output of an integration element is held at the value showing the speed of 0. An addition circuit adds the signal showing the bias position of the spool inputted through the switch from the spool position command signal output means, and the signal showing O outputted from the integration element, and inputs them into 3 port valves. For this reason, the above-mentioned 3 port valves are located in the predetermined bias position which connects a load port to a tank, and stop an actuator. At this time, an integration element keeps the value of 0 and does not keep a negative value like the former. 3 port valves do not shift a spool to the position which makes a tank open a load port for free passage too much, and it is making the bias position which carried out the small shift of the spool very much at the position side which makes a tank open a load port for free passage from a neutral position stop them. If the target speed of an actuator is set as values other than zero in this state, it is a switch control circuit, The switch which controls inputting the output from the 1st subtraction circuit into an integration element is turned ON, other switches are turned OFF, the feedback loop which returns the output of an integration element to an input is cut, and an integration initial value output means and a spool position command signal output means are cut off. Therefore, in the 1st subtraction circuit, the deviation of target speed and the velocity feedback signal from a speed sensor is taken, this deviation is inputted into an integration element, and it finds the integral, and also the output of an integration element is inputted into 3 port valves, and controls an actuator. In order that the output of an integration element may recover from the state of 0 currently held at this time and the spool of 3 port valves may operate from the bias position specified by the spool position command signal output means, The standup of the output of an integration element is quick, and, as for short Nuclear, therefore an actuator, a distance of a spool until 3 port valves output fluid of operation recovers from a state of rest quickly.

[Example]

Hereinafter, the example of illustration of this invention explains in detail. Drawing 3 shows this whole example composition, and only control device 30 differs from a conventional example. The above-mentioned control device 30 is carrying out composition as shown in Drawing 1. Switch control circuit 21 compares the absolute value of target speed T with minute standard value R for distinguishing whether target speed is O, When absolute value T1 of target speed T is smaller than standard value R, switches 23 and 24 are turned ON, Switch 22 is turned OFF, when absolute value ITI of target speed T is greater than standard value R, namely, target speed T is not 0, switch 22 is turned ON and switch 23 and switch 24 are turned OFF. The 1st subtraction circuit 31 computes a deviation with velocity feedback signal F from speed sensor 2 which detects target speed T and the speed of oil pressure cylinder l, and outputs this deviation to integration element 33 via switch 22. When target speed T of the 2nd subtraction circuit 32 is 0, A deviation with the output of integration element 33 inputted via the integration initial value (V+=O) and switch 23 which were inputted via switch 23 from integration initial value output means 35 is computed, and it inputs into integration element 33, and makes integration initial value ■1 hold to integration element 33. When target speed T is not 0, the above-mentioned 2nd subtraction circuit 32 inputs into integration element 33 the signal inputted via switch 22 from the 1st subtraction circuit 31. The spool of 3 port servovalve 5 which spool position command signal output means 36 shows in Drawing 3 is neutral position S. also depending -- the signal showing being in the position (henceforth a negative bias position) by the side of left-hand side symbol position St very slightly is outputted. Addition circuit 37 applies the signal showing the negative bias position inputted via switch 24 from spool position command signal output means 36, and the output of integration element 33, and outputs them to 3 port servovalve 5. The above-mentioned addition circuit 37 outputs the output of an integration element to 3 port servovalve 5 as it is, when switch 24 is OFF. The concrete composition of the above-mentioned integration element 33 and the 2nd subtraction circuit 32 is shown in Drawing 2. The above-mentioned integration element 33 consists of comparator 51, capacitor C, and resistance R, the 2nd subtraction circuit 32 consists of Hamparator 32, and switch 22*23 shown in Drawing 1 is arranged as shown in Drawing 2. Switch 23 shown by two blocks in Drawing 1 is shown by one block in Drawing 2. An integration gain is determined by capacitor C and resistance R. Resistance r is a small value in order to perform integration element 33 or initialization at high speed. Operation of the control device of the above-mentioned composition is explained while referring to Drawing 1. Now, supposing target speed T is 0, switch control circuit 21 compares minute standard value R for distinguishing whether speed is 0 from absolute value IT of this target speed T, since it is l T l <H, will turn ON switch 23 and switch 24, and will turn OFF switch 22. Therefore, the 1st subtraction circuit 31 is separated from the 2nd subtraction circuit 32, and the 2nd subtraction circuit 32 is, The deviation of voltage ■1-O which is an integration initial value showing the speed of 0 inputted from integration initial value output means 35, and the output of integration element 33 fed back via switch 23 is taken, and this deviation is inputted into integration element 33. Therefore, the integration initial value to which the above-mentioned integration element 33 expresses speed 0 outputted from integration initial value output means 35 is held. Addition circuit 37 adds the signal showing the negative bias position inputted into integration element 33 as integration initial value V showing kept speed 0, and =O via switch 24 from spool position command signal output means 36, and outputs it to 3 port servovalve 5. Therefore, the above-mentioned 3 port servovalve 5 makes the position which carried out small displacement very much from neutral position S0 shown in Drawing 3 at left-hand side position S and the side suspend a spool, makes tank 7 open a load port for free passage, and it keeps oil pressure cylinder 1 from moving forward by the leak of 3 port servovalve 5. Next, since switch control circuit 21 is larger than very small standard value R for absolute value ITI of target speed T to distinguish zero when target speed T other than zero is inputted into control device 30 from the state in which oil pressure cylinder l stood it still in this way, Switch 22 is turned ON and switch 23.24 is turned OFF. Therefore, the loop which integration initial value output means 35 and spool position command signal output means 36 are separated from a circuit, and holds the output of integration element 33 is also cut. In a direction, since switch 22 is set to ON, the same circuit as the usual speed feedback loop is constituted. Therefore, in the 1st subtraction circuit 31, a deviation with velocity feedback signal F from target speed T and speed sensor 2 is calculated, This deviation is inputted into integration element 33 via switch 22, and integration is performed so that a remains deviation may not arise, The output from integration element 33 is outputted to 3 port servovalve 5 via addition circuit 37, displaces the spool of 3 port servovalve 5 in a predetermined position, and operates oil pressure cylinder l at the rate of predetermined. Thus, since integration element 33 keeps the value of 0 just before that when target speed T other than zero is inputted, In order to operate from the negative bias position where the output of integration element 33 rose quickly, and spool 5 of 3 port Saho valve was also defined by spool position command signal output means 36 and which carried out the knot to small Nimbol position S and the side very much, There are few shift amounts of a spool until 3 port servovalve 5 outputs a predetermined flow. Therefore, a standup until 3 port servovalve 5 outputs a predetermined flow can make oil pressure cylinder 1 recover from a state of rest quickly early extremely. Although he is trying to control switch 22.23*24 by switch control circuit 21, it may enable it to control a switch by the above-mentioned example compulsorily by other means in addition to switch control circuit 21. Although 3 port servovalve was used as 3 port valves in the above-mentioned example, the three-point 1 A proportioning valve which operates by proportionality solenoid which produces the power of absorption proportional to a current value may be used.

[Effect of the Invention]

As mentioned above, when target speed is O in the present invention clearly, While making an integration initial value corresponding to speed of O outputted to an integration element from an integration initial value output means hold, A spool is displaced in a negative bias position equivalent to a signal outputted to 3 port valves from a spool position command signal output means, When target speed is inputted [ target speed other than zero ] from a state of 0, while, separating an integration initial value output means and a spool position command signal output means from a circuit with a switch on the other hand, A loop which returns an output of an integration element to the input side is cut, and it asks for a deviation of target speed and a velocity feedback signal from a speed sensor in the 1st subtraction circuit, outputs to an integration element, and controls 3 port valves. Therefore, when target speed other than zero is inputted for target speed in the state of 0, An integration element rises from an integration initial value currently held to a predetermined value immediately, The spool of 3 port valves can move migration length slight to a position which obtains a predetermined output flow rate from a negative bias position which has not been shifted to an un-controlling side too much, therefore can perform a standup from a halt condition of an actuator quickly.

[Brief Description of the Drawings]

The figure and Drawing 4 showing the circuit composition whose Drawing 3 Drawing 2 controls Drawing 1 by the block diagram of the control device of 3 port valves of this invention, control it by the concrete circuit lineblock diagram of an integration element and the 2nd subtraction circuit, and controls an oil pressure cylinder by a servovalve are a block diagram of the control device of the conventional 3 port valves. l ... An oil pressure cylinder, 2 ... A speed sensor, 3.30 ... Control device, 5.8 ... 3 port servovalve, 6 ... pressure source, 21 ... switch control circuit, 22.23.24 ... switch, 31 ... the 1st subtraction circuit, 32 ... the 2nd subtraction circuit, 33 ... integration element, 37 ... addition circuit, 35 ... integration initial value output means, 36 ... spool position command signal output means.