DE3422978A1 - Arrangement for controlling a hydraulic actuating device - Google Patents

Abstract

An arrangement (10) for controlling the rapid traverse and feed of a hydraulic actuating device is proposed, the hydraulic motor (11) of which can be controlled in both directions with regard to direction and speed. Lying between a proportional valve (15) and the hydraulic motor (11) in one (24) of the working lines (22, 24) is a pressure balance (33) which interacts with the proportional valve (15) as a flow controller, for which purpose both valves (15, 33) are connected to one another via control lines (38, 39) in which an additional, switching 4/2-way control valve (42) is connected, while a counterholding pressure valve (47) lies in the other working line (22). The controllable pressure balance (33) works as a downstream inflow controller during forward feed and as an upstream outflow controller during reverse feed and at the same time as a counterholding pressure valve. In addition, to avoid starting surges, the pressure balance (33) can activate its control position starting from a blocking position. <IMAGE>

Description

Device for controlling a hydraulic actuator

prior art device The invention is based on a device for controlling a hydraulic actuator according to the preamble of the main claim. Such a device is already known from DE-OS 24 61 021, in which the Functions of the direction control of a double-acting hydraulic motor together with the pressure compensator function are combined in one slide axis, while a second Slide axis is assigned to a proportional throttle valve. The proportional throttle valve assumes the function of a measuring orifice, which together with the pressure compensator a Current controller function results. When the hydraulic motor is extending, the proportional throttle valve is located here in the outflow stream upstream of the pressure compensator, while it is when the hydraulic motor is retracting the pressure compensator is seated in the feed stream downstream. A disadvantage of this device is that here the first valve axis for the direction control and the pressure compensator function builds relatively expensive. This is how the slide of the first valve axis works for the Pressure compensator function with two springs and with several control edges; In addition, two switching pistons and several pressure chambers are required. This valve axis is therefore difficult to derive from a standard valve series. Further can be disadvantageous that no pressure valves in the for a counter-hold function Working lines are provided. Through the combined functions of directional control and pressure compensator, the control spool is only in its central position by springs centered; this requires a very high manufacturing accuracy of the springs. Further the springs may change differently with a longer service life.

Furthermore, from DE-OS 32 35 954 a device for control the rapid traverse and the feed rate of a machine tool slide with the aid of a double-acting working cylinder known in which a pressure compensator in a feed line is connected between a pump and a proportional directional control valve. Be here the functions of the direction control of the working cylinder and the orifice plate for the flow control function perceived by the proportional directional control valve. A disadvantage with this device is that this requires an expensive proportional valve is designed as a 4-way 5-position valve. Also are here for the counter-hold function has two pressure valves and one associated check valve each required in a correspondingly large nominal size, which increases the cost of the device.

Advantages of the invention The device according to the invention with the characterizing Features of the main claim has the advantage that it is a simple one and precise control of the dilatation and advance of the hydraulic motor in both Directions allowed with a minimum number of devices using valves that are as standard as possible. The switchable pressure compensator can now take on several functions by using retracting cylinder performs the function of a counterbalance valve. It can be thus a pressure valve for the counter-hold function and a check valve for Save parallel bypassing of the pressure valve in each case in a large nominal diameter, which and brings space advantages. The pressure compensator is directly in the working line connected between hydraulic motor and proportional valve. It is therefore also omitted in this connection an additional leakage oil valve, its leakage oil flows could disturb a constant work feed rate. The minimum achievable The working feed rate can therefore be selected to be even smaller. In addition, lies In the case of the proportional directional control valve, the control slide defines between mechanical off beats.

The measures listed in the subclaims are advantageous Developments and improvements of the device specified in the main claim possible. An embodiment according to claim 7 is particularly advantageous, whereby the Switchable pressure compensator also used for a jump-free feed control will. Further advantageous refinements emerge from the drawing and FIG Description.

DRAWING Three exemplary embodiments of the invention are shown in the drawing and explained in more detail in the following description. It show figure 1 shows a first embodiment of the device with a proportional directional control valve, Figure 2 shows a second embodiment with a proportional throttle valve and Figure 3 a part a third device with a proportional directional control valve to prevent jump start.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS FIG. 1 shows an apparatus 10 for controlling a hydraulic actuator that has a double-acting Has hydraulic motor 11. The hydraulic motor 11 is designed as a differential cylinder, the piston 12 of which separates a piston rod space 13 from a cylinder space 14.

A proportional directional control valve is used to control the direction of the hydraulic motor 11 15 provided in a pilot-operated design. Its inlet connection marked with P. 16 is in connection with a pump 17, while its return connection, designated by T, is connected 18 has connection with the tank 19. A consumer connection 21 labeled A is in connection with the piston rod space 13 via a first working line 22, while from the consumer connection 23 designated by B, a second working line 24 leads to the cylinder space Ib.

The proportional directional control valve 15 is designed as a kWege 3-position valve and also has a first (25) and a second control connection 26. Both control connections 25, 26 and the inlet connection 16 are blocked in the calculated middle position 27. In contrast, both consumer connections 21, 23 are in the same position 27 with the Return connection 18 connected.

The control slide of the proportional directional control valve 15 is out of the middle position 27 can be deflected out to both sides in working positions, the cross position 28 and as parallel position 29 are designated. the Cross position 28 is designed so that the inlet connection 16 to the second consumer connection 23 via an orifice plate 31 has connection and the pressure is upstream of this Orifice 31 is fed to the second control connection 26. At the same time is in the cross position 28 the first control connection 25 blocked, while the first consumer connection 21 to the return port 18 is relieved. The parallel position 29 is designed so that the second consumer connection 23 to the return connection 18 via an orifice plate 32 is relieved and thereby the pressure downstream of the measuring orifice 32, that is in the return connection 18, the first control terminal 25 is supplied.

The measuring orifices designed to be adjustable in the proportional directional control valve 15 31, 32 work together with a pressure compensator 33 in the manner of a flow regulator. the Pressure compensator 33 is designed as a 2-way valve and directly into the second working line 24 connected between the proportional directional control valve 15 and the hydraulic motor 11. the Pressure compensator 33 has one of the control pressures in a spring chamber 34 and a pressure chamber 35 can be acted upon slide 36, which is operated by a spring 37 in the direction of the open position is burdened.

The spring chamber 34 of the pressure compensator 33 is connected to a first control line 38 with the second working line 24 in the area between the pressure compensator 33 and the proportional directional control valve 15 in connection. In addition, a second control line leads from the pressure chamber 35 of the pressure compensator 33 39 to the second control connection 26 in the proportional directional control valve 25.

A parallel branch line also leads from the second control line 39 41 to the first control connection 25 on the proportional directional control valve 15.

In the two control lines 38, 39 is a pressure compensator 33 controlling 4/2 control valve 42 switched. In a cross position 43 of the control valve 42 are on the one hand the two sections of the first control line 38 connected to one another, while at the same time the pressure chamber 35 via the second control line 39 with both control connections 25, 26 in the proportional valve 15 has connection. In a parallel position 44 of the Control valve 42, the control connections are interchanged, so that then the spring space 34 receives the control pressure tapped in the proportional valve 15, and the pressure chamber 35 with the pressure in the second working line 24 between the pressure compensator 33 and the proportional valve 15 is applied.

The control valve 42 is actuated by two switching solenoids 45, 46 and is locked in its two positions 43, 44.

In the first working line 22 is between the hydraulic motor 11 and the proportional directional control valve 15, a controllable pressure relief valve 47 is connected as a counterbalance valve.

To bypass this pressure relief valve 47 lies parallel to it a first check valve 48 which opens towards the piston rod space 13.

For a rapid traverse shift, the piston rod space 13 is via a return line 49 and a second check valve (51) connected to the output of the pump 17, the second check valve 51 opening towards the latter.

The operation of the device 10 is explained as follows: For a hydraulic feed control becomes one of force or pressure fluctuations independent, constant feed rate required. This requires both a Regulation of the feed rate influencing the volume flow as well as a Counter-hold of the extending or retracting hydraulic motor 11, i.e. one hydraulic counterforce directed against the feed direction. This counterforce is when the piston rod 12 'extends in a manner known per se by the controllable Pressure relief valve 47 applied. On the other hand, when the piston rod is retracted 12 'perceived this counter-hold by the pressure compensator 33, which is also associated with the Orifice plates in the proportional directional control valve 15 cooperate in the manner of a flow control valve.

To the hydraulic motor 11 in the direction of arrow 52 in Figure 1 in rapid traverse To steer forward, the proportional directional control valve 19 is in its cross position 28 controlled, the control valve 42 occupies the drawn cross position 4a. Pressure medium delivered by the pump 17 flows through the proportional directional control valve 15, the second working line 24 with the pressure compensator 33 into the cylinder space 14 of the Hydraulic motor 11. Pressure medium displaced from piston rod space 13 flows over the return line 49 and the check valve 51 also to the inlet connection 16 of the proportional directional control valve 15, so that the piston rod 12 'in the manner of a conventional Plunger shift extends quickly. During rapid forward are the working pressures so low that over the pressure relief valve 47 with the appropriate pressure setting the same no pressure medium flows off.

During the forward rapid traverse the pressure acts upstream of the Measuring orifice 31 via the second control connection 26 and the second control line 39 in the pressure chamber 35. At the same time, the pressure downstream of the same measuring orifice 31 from the second working line 24 via the first control line 38 into the spring chamber 34 transferred.

The pressure compensator 33 thus has the effect of being independent of pressure fluctuations on the pump side 17 or in the event of load fluctuations on the hydraulic motor 11 is always a constant pressure gradient across the orifice plate 31 and thus a constant volume flow for the rapid traverse movement on the hydraulic motor 11 is available stands.

Depending on the position of the extending piston rod 12 ', FIG Arrow 53 switched from rapid traverse to working feed forward. The orifice plate is thereby 31 in the proportional directional control valve 15 significantly reduced in cross section, so that now a small volume flow required for the working feed to the cylinder chamber 14 flows. The pressure compensator 33 keeps the volume flow constant in the same way. As a result of the higher working pressure, that which is displaced from the piston rod space 13 flows Pressure medium now from the first working line 22 to the tank 19. The pressure relief valve 47 thereby exercises its counter-holding function in a manner known per se. Of course the speed at the work feed forward is proportional to that at the proportional variable speed valve 15 entered, electrical setpoint adjustable. In addition to the function of speed control The proportional directional control valve 15 also takes on the function of directional control at the same time of the hydraulic motor 11. The control valve is also located at the working feed forward 42 in the drawn cross position 43, so that with the same flow direction of the Volume flow through the pressure compensator 33 the same control connections during rapid traverse and work feed act.

If the extended piston rod 12 'according to arrow 54 in Figure 1 with Working feed retracted backwards, so the proportional directional control valve 15 is off the middle position 27 is deflected out in the direction of the parallel position 29. Simultaneously the control valve 42 is moved by its switching magnet 46 into the parallel position 44 brought.

Pressure medium delivered by the pump 17 now flows over the first Working line 22 and its check valve 48 in the piston rod space 13. From the cylinder chamber 14 displaced pressure medium must be via the second working line 24, the pressure compensator 33 and the proportional directional control valve 15 flow off to the tank 19. Included the measuring orifice 32 is now effective in the proportional valve, which is for the work feed is only slightly open backwards, and when the hydraulic motor 11 retracts according to Art a sequence circuit works, in contrast to the inlet circuit of the measuring orifice 31 with extending piston rod 12 '. 3 in this sequence switching during the work feed backwards the pressure compensator 33 is now upstream of the measuring orifice 32. By the Parallel connection 44 in control valve 42, the control connections are now interchanged so that that the pressure drop across the measuring orifice 32 on the slide 36 of the pressure compensator 33 in turn the force of the spring 37 counteracts. This means that the from Hydraulic motor 11 outflowing pressure medium flow kept constant and thus also the Work feed backwards. When the piston rod 12 'moves in, the pressure compensator takes over 33 by the sequence circuit together with the throttle function of the measuring orifice 32 in the Proportional directional control valve 15 also has the counter-hold function. It can therefore an additional brake / pressure valve with a large nominal diameter and an associated check valve can be saved for bypassing.

When the piston rod 12 'moves in, it is position-dependent on the working feedrate is switched backwards to reverse rapid traverse according to arrow 55 in FIG the orifice plate 32 in the proportional directional control valve 15 is fully opened, the control valve 42 continues to assume its parallel position 44. The pressure compensator 33 also takes care of this for a constant volume flow independent of load changes on the hydraulic motor 11 or pressure changes on the pump side 17.

By switching the pressure compensator 33 in the working line between Hydraulic motor 11 and proportional valve 15 is achieved that in this connection no leakage valve has to be arranged additionally.

This also eliminates the need for such valves with leakage oil leakage oil flows that change from pressure fluctuations, which maintain a constant working feed rate could disturb. The achievable, minimum work feed rate can therefore can be chosen even smaller. This is particularly important when there is a major problem Temperature fluctuations affect the viscosity of the pressure medium and thus the size which can change leakage oil flows.

Figure 2 shows a second device 60, which differs from that according to Figure 1 differs as follows, with the same reference numerals for the same components be used.

In the case of the second device 60, those in FIG. 1 are in the proportional valve 15 combined functions for direction control and speed control now implemented in two separate valves, namely the directional control in one 4/3-way valve 61 and the speed control in a proportional throttle valve 62. The directional control valve 61 can thereby be designed as a simple switching valve and the proportional throttle valve 62 only needs to control two ways, so that it is much easier to build. At the proportional throttle valve 62 is next to Inlet connection 16 and the second consumer connection 23, only the second control connection 26 is required, which is connected to the second control line 39 in a corresponding manner is. The two working lines 22 and 24 are now directly on the 4/3-way valve 61 connected, so that in the second working line 24, the pressure compensator 33 and the Proportional throttle valve 62 lie in series with one another. A return line 49 omitted, so that in rapid traverse forward and rapid reverse on Hydraulic motor 11 the pressure medium volume pushed out in each case via the directional control valve 61 flows to the tank 19.

The mode of operation of the second device 60 corresponds accordingly that of the first device 10, wherein for direction control for forward and backwards on the hydraulic motor 11, the corresponding magnets 63 or 6V on the switching Directional valve 61 must be energized and the speed control from the proportional throttle valve 62 is taken over, its associated proportional magnet only in one direction must work. The function of the pressure compensator which can be switched with the aid of the control valve 42 33 remains unchanged.

FIG. 3 shows part of a third device 70 with which In a particularly simple and advantageous manner, a jump-free feed control can be achieved. The third device 70 is different from the first device 10 according to FIG. 1 as follows, the same reference numerals being used for the same parts will.

The third device 70 is a different proportional directional control valve 71 used, in which in the middle position 27 of the second control terminal 26 via a Cross connection 72 with the inlet connection 16 has connection. Through this special Middle position 27 can be reached together with the switchable pressure compensator 33, that at the beginning of a work feed movement forwards or backwards the slide 36 in the pressure compensator 33 instead of the open always from its closed Position moved to the control position.

The proportional directional control valve is at the start of a forward working feed movement 71 in its middle position 27, and the 4/2 control valve 42 in its cross position 43. The pressure building up in the inlet connection 16 can now via the cross connection 72, the second control connection 26 and the second control line 39 act in the pressure chamber 35 and the slide 36 of the pressure compensator 33 against the force push its spring 37 into a locking position.

At the same time, the spring chamber 34 is in the middle position via the first control line 38 27 of the proportional directional control valve 71 to the tank 19 is relieved. With the start of the work feed switches the proportional directional control valve 71 in the direction of its cross position 28; the The slide 36 in the pressure compensator 33 moves out of the closed position into its control position and thereby avoids a jump start.

The proportional directional control valve 71 is at the working feed backward and the control valve 42 again in the same starting positions, namely the middle position 27 or the cross position 43. The pressure compensator 33 is therefore closed.

At the beginning of the working feed both valves 71 switch backwards, 42 at the same time in their parallel positions 29 and 44, the slide 36 in the pressure compensator 33 in turn moved from its closed position to the rule. An approach jump is also avoided here.

Changes to the devices shown are of course possible possible without deviating from the concept of the invention. So the valves for the functions of direction control and speed control as well as direct actuated as well as pilot operated valves are designed. The feed control is also not limited to the differential cylinder shown as a hydraulic motor its place in a circuit according to Figure 2 also a working cylinder with the same large effective areas can be used.

A circuit is particularly advantageous if a differential cylinder Compared to FIG. 2, connected to the working lines 22, 24 reversed will; So the cylinder space 14 to the first (22) and the Koioenstangenraum 13 to the second working line 24. Then the pressure compensator 33 takes over the counter-hold with extending piston rod. In the case of heavily fluctuating loads, e.g. in the case of a breakthrough Drill, this results in a reliable clamping. Even with the piston rod retracting a rapid traverse and a work feed rate can be achieved. The countermeasure by the Pressure compensator can be much stronger than with a counter-holding pressure relief valve.

Claims (10)

Claims 1. Device for controlling a hydraulic actuator, which has a double-acting hydraulic motor, from which two working lines are closed the direction of the hydraulic motor controlling directional control valve means, which on the other hand are in communication with a pressure medium source and a tank as well as with a Current regulator formed from measuring orifice and pressure compensator to control the feed rate of the hydraulic motor, the measuring orifice being adjustable in the form of a proportional valve is formed, the pressure difference of which can be fed to the pressure compensator via control lines is, characterized in that the pressure compensator (33) as one of the direction control separate 2-way valve is formed, which in the working line (24) between Hydraulic motor (11) and proportional valve (15; 62) is connected that at least one (39) of the control lines (38, 39) from the proportional valve (15; 62) in controllable Way can be influenced and that in both control lines (38, 39) between the pressure compensator (33) and proportional valve (15; 62) a control valve that switches the pressure compensator (33) (42) lies. 2. Apparatus according to claim 1, characterized in that the control valve is designed as a 4-way 2-position valve (42), with which the connections via the both Control lines (38, 39) according to the different Flow through the pressure compensator (33) and its position in relation to the proportional valve (15; 62) are switchable. 3. Apparatus according to claim 1 or 2, characterized in that in the working line (22) not routed via the pressure compensator (33) a pressure valve (47) is connected as a counterbalance valve, to which one in the direction of the hydraulic motor (11) opening check valve (48) is connected in parallel. 4. Device according to one or more of claims 1 to 3, characterized characterized in that the proportional valve is one of the directional control valve (61) for the directional control separate proportional throttle valve (62) is the at least one controlled Has control connection (26) for a control line (39). 5. Device according to one or more of claims 1 to 3, characterized characterized in that the proportional valve as a direction control with taking over Proportional directional valve (15; 71) is formed; 6. Apparatus according to claim 5, characterized in that the proportional directional control valve (15; 71) has two control connections (25, 26), which are connected in parallel to the same connection of the control valve (42) are. 7. Device according to one or more of claims 1 to 6, characterized characterized in that in the middle position (27) of the proportional valve (71) a control connection (26) is connected to the inlet connection (J6) and the control valve (42) is connected to the pressure compensator (33) initially controls to avoid a starting jump. 8. Device according to one or more of claims 1 to 7, characterized characterized in that the proportional valve (15, 62, 71) has a cross position (28) has, in which the pressure compensator (33) as a downstream feed flow regulator works and at which the pressure upstream of a measuring orifice (31) in the proportional valve a control connection (26) is fed and the slide (36) of the pressure compensator (33) loaded in the closing direction. 9. Device according to one or more of claims 1 to 8, characterized characterized in that the directional control valve means (15; 61) for direction control have a parallel position (29), in which the pressure compensator (33) as an upstream discharge flow regulator works and in which the pressure flow downstream of a measuring orifice (32; 31) in the proportional valve a control connection (25; 26) and the slide (36) of the pressure compensator (33) loaded in the opening direction. 10. Device according to one or more of claims 1 to 9, characterized characterized in that the pressure compensator has the counter-hold function in the case of an extending Piston rod during the working or rapid feed forward of the hydraulic motor exercises.