DE3422978C2 - Device for controlling a hydraulic actuating device - Google Patents

Description

The invention relates to a control device a hydraulic actuator according to that in the preamble of claim 1 specified genus.

It is already such a device for controlling a hydraulic actuator from DE 25 19 697 A1 known in which a double-acting hydraulic motor from one controlling the direction, as an orifice plate of a current regulator working proportional valve is controllable to the Current control in the tank line assigned a pressure compensator is. If the pressure compensator with this sequence switch Takes over the function of the counterhold, builds up in the upstream section of the tank line a pressure that is effective in the T-port of the proportional valve and leads to a particularly expensive construction. Further the proportional valve is a valve with leakage oil, so that with the counter function by the pressure in the T-termination leak oil over the Proportional valve can drain and the accuracy of a Feed control interferes, which is particularly the case with small ones Pressure medium flows or low speeds of the Hydromotors and the loss balance of the System deteriorated. The device also works with Flow directional valves, which are connected as anti-parallel Check valves are in the working line; she cause constant losses in the power flow and thus Heat that has to be dissipated in a complex manner. In addition the flow directional valves are used to control a  elaborate 5-way control valve with which the Proportional valve occurring in changing directions Pressure drop is performed on the pressure compensator.

A device is also known from DE 24 61 021 A1, where the functions of directional control one double acting hydraulic motor together with the Pressure compensator function are combined in a slide axis, while a second slide axis one Proportional throttle valve is assigned. The Proportional throttle valve takes over the function of a Orifice plate, which together with the pressure compensator Current controller function results. With the hydraulic motor extending here the proportional throttle valve is in the drain flow upstream of the pressure compensator while it is at incoming hydraulic motor in the feed stream downstream of the Pressure compensator sits. The disadvantage of this device is that here is the first valve axis for directional control and builds the pressure compensator function relatively complex. So the slide of the first valve axis works for the Pressure compensator function with two springs and with several Control edges; there are also two switching pistons and several Pressure chambers necessary. That is why this valve axis is bad from a standard valve series derivable. It can also be disadvantageous that for a Counter pressure function no pressure valves in the Working lines are provided. By the combined Functions of directional control and pressure compensator is the Control spool only by springs in its central position centered; this requires a very high level of manufacturing accuracy the feathers. Furthermore, the springs can last longer Change lifespan differently.  

Furthermore, DE 32 35 954 A1 describes a device for Control of rapid traverse and feed of one Machine tool slide with the help of a double-acting Working cylinder known in which a pressure compensator in a Inlet line between a pump and a Proportional directional control valve is switched. Here are the Functions of the direction control of the working cylinder and the orifice for the current control function from Proportional directional control valve perceived. A disadvantage of this The device is that this is a complex Proportional valve is necessary as a 4-way 5-position valve is trained. Also here for the counter function two pressure valves and one each assigned check valve in a correspondingly large size Nominal size required, which increases the cost of the device.

The object of the invention is a generic Device for controlling rapid traverse and feed of a double-acting hydraulic motor with an as Counter function usable switchable pressure compensator as simple as possible so that a more accurate and less loss of work is possible.

This task is solved starting from a device according to the preamble of claim 1 with the characterizing Characteristics. The device according to the invention has the advantage that they have low loss and accurate control of rapid traverse and feed of the hydraulic motor in both directions minimum number of devices using as simple as possible Valves allowed. The switchable pressure compensator takes over several Functions by performing the function when the cylinder is retracting a counterbalance valve. It gets involved with it Pressure valve for the counter function as well as a Check valve to bypass the pressure valve in parallel Save in large nominal sizes. The pressure compensator is  directly into the working line between the hydraulic motor and Proportional valve switched. This eliminates this Connection an additional leak oiled valve, the Leakage oil flows a constant feed rate could disturb. The pressure compensator is not contaminated with oil Component and prevents the function of Counteract a leakage oil flow via the proportional valve to the tank. The minimum attainable The feed rate can therefore be reduced even further choose. In addition, the proportional directional valve is the Control spool defines between mechanical deflections.

By the measures listed in the subclaims advantageous developments and improvements in Claim 1 specified device possible. Especially An embodiment according to claim 6 is advantageous, whereby the switchable pressure compensator also for one start-free feed control is used.

Three embodiments of the invention are in the Drawing shown and in the description below exercise explained in more detail. Show it

Fig. 1 shows a first exemplary embodiment of the device with a proportional directional control valve, Fig. 2 shows a second embodiment with a proportional throttle valve and Fig. 3 shows part of a third device with a Proportionalwegeven valve for starting jump prevention.

Description of the embodiments

Fig. 1 shows a device 10 for controlling egg ner hydraulic actuator, which has a double-acting hydraulic motor 11 . The hydraulic motor 11 is designed as a differential cylinder, the piston 12 of which separates a piston rod chamber 13 from a cylinder chamber 14 .

To control the direction of the hydraulic motor 11 is a proportional directional valve is seen in 15 pilot-operated construction before. His designated P inlet port 16 is connected to a pump 17 , while his return port 18 with T be connected to the tank 19 connec tion. A designated with A consumer port 21 is connected via a first working line 22 with the piston rod chamber 13 , while from your B designated consumer port 23 leads a second working line 24 to the cylinder chamber 14 .

The proportional directional control valve 15 is designed as a 4-way 3-position valve and also has a first ( 25 ) and a second control connection 26 . Both Steueran connections 25 , 26 and the inlet connection 16 are blocked in the center position 27 shown . In contrast, both actuator ports 21, 23 in the same lung Stel 27 are connected to the return port 18th

The spool of the proportional directional valve 15 is deflected from the central position 27 out to both sides in working positions, which are referred to as the crossover position 28 as well as a parallel position 29th The cross position 28 is designed so that the supply connection 16 to the second consumer connection 23 via a measuring orifice 31 has connection and the pressure upstream of this measuring orifice 31 to the second Steueran circuit 26 is supplied. At the same time in the cross position 28 of the first control connection 25 is blocked, while the first consumer connection 21 to the Rücklaufan circuit 18 is relieved. The parallel position 29 is designed such that the second consumer connection 23 to the return connection 18 is relieved via a measuring orifice 32 and the pressure downstream of the measuring orifice 32 , that is to say in the return connection 18 , is fed to the first control connection 25 .

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

The spring chamber 34 of the pressure compensator 33 is connected via a ste control line 38 to the second working line 24 in the area between the pressure compensator 33 and the proportional travel valve 15 . In addition, from the pressure chamber 35 of the pressure compensator 33, a second control line 39 leads to the two control port 26 in the proportional directional valve 15 . A parallel branch line 41 leads from the second control line 39 to the first control connection 25 on the proportional directional control valve 15 .

In the two control lines 38 , 39 , a pressure balance 33 controlling 4/2 control valve 42 is connected. In a cross position 43 of the control valve 42 , on the one hand the two sections of the first control line 38 are connected to one another, while at the same time the pressure chamber 35 has connections 25 , 26 in the proportional valve 15 via the second control line 39 . In a parallel position 44 of the control valve 42 , the control connections are interchanged, so that the spring chamber 34 then receives the control pressure tapped in the proportional valve 15 , and the pressure chamber 35 is pressurized with the pressure in the second working line 24 between the pressure balance 33 and the proportional valve 15 . The control valve 42 is actuated by two switching magnets 45 , 46 and is locked in its two positions 43 , 44 .

A controllable pressure relief valve 47 is connected in the first working line 22 between the hydraulic motor 11 and the proportional directional control valve 15 as a counterbalance valve. To bypass this pressure relief valve 47, there is a first check valve 48 parallel to it, which opens towards the piston rod chamber 13 .

For a rapid traverse, the piston rod chamber 13 is connected via a return line 49 and a second check valve 51 to the outlet of the pump 17 , where the second check valve 51 opens towards the latter.

The mode of operation of the device 10 is explained as follows: For a hydraulic feed control, a constant feed rate is required which is independent of force or pressure fluctuations. This requires both a regulation of the flow rate influencing the feed rate and a countermeasure of the extending or retracting hydraulic motor 11 , ie a hydraulic force directed against the feed direction. This counterforce is applied when rod Kol extending 12 'in a conventional manner by the controllable pressure relief valve 47 . Since against this is counteracted by the pressure compensator 33 when retracting the piston rod 12 ', which additionally cooperates with the measuring orifices in the proportional directional control valve 15 in the manner of a flow control valve.

In order to control the hydraulic motor 11 according to arrow direction 52 in FIG. 1 in rapid traverse, the proportional directional valve 19 is controlled into its cross position 28 , where the control position 42 assumes the cross position 43 shown . Pressure medium conveyed by the pump 17 flows via 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 . From the piston rod space 13 displaced pressure medium flows via the return guide line 49 and the check valve 51 also to the inlet port 16 of the proportional directional control valve 15 , so that the piston rod 12 'quickly extends in the manner of a conventional plunger circuit. During the express gear forward, the working pressures are so low that no pressure medium flows out via the pressure relief valve 47 with the appropriate pressure setting.

During the rapid forward movement, the pressure acts upstream from the orifice 31 via the second Steueran circuit 26 and the second control line 39 in the pressure chamber 35 . At the same time, the pressure is transmitted downstream from the same orifice 31 from the second working line 24 via the first control line 38 into the spring chamber 34 . The pressure compensator 33 thus has the effect that, regardless of pressure fluctuations on the pump side 17 or load fluctuations on the hydraulic motor 11, a constant pressure drop across the orifice plate 31 is always effective and thus a constant volume flow for the rapid traverse movement on the hydraulic motor 11 is available.

Depending on the position of the moving piston rod 12 'is switched according to arrow 53 from rapid traverse to feed forward. The orifice 31 in the proportional directional control valve 15 is substantially reduced in cross section, so that a small volume flow required for the working feed now flows to the cylinder space 14 . The pressure compensator 33 keeps the volume flow constant in the same way. As a result of higher working pressure, the pressure displaced from the piston rod chamber 13 now flows from the first working line 22 to the tank 19 . The pressure limiting valve 47 performs its counter-holding function in a manner known per se. Of course, the speed at work feed forward is adjustable in proportion to the electrical setpoint entered on the proportional directional control valve 15 . In addition to the function of speed control, the proportional directional control valve 15 also takes on the function of direction control of the hydraulic motor 11 . When working feed forward, the control valve 42 is in the cross position 43 shown , so that with the same flow direction of the volume flow through the pressure compensator 33 the same control connections act during rapid traverse and Ar beitsvorschub.

If the extended piston rod 12 'according to arrow 54 in Fig. 1 retracted with feed, the proportional directional control valve 15 is steered out of the central position 27 in the direction of the parallel position 29 from. At the same time, the control valve 42 is brought into the parallel position 44 by its switching magnet 46 .

Pressure medium delivered by the pump 17 now flows via the first working line 22 and its check valve 48 into the piston rod chamber 13 . Pressure medium displaced from the cylinder chamber 14 must flow out to the tank 19 via the second operating line 24 , the pressure compensator 33 and the proportional directional valve 15 . The orifice plate 32 is now in the proportional valve effect, which is only slightly opened to working feed backward, and the working circuit for the retracting hydraulic motor 11 in the manner of a sequence, as opposed to the feed circuit of the measuring orifice 31 on extending the piston rod 12 '. In the ser drain circuit during the work feed back Windwärts now the pressure regulator 33 is located upstream of the orifice gauge 32nd Through the parallel connection 44 in the control valve 42 , the control connections are now interchanged so that the pressure drop across the orifice plate 32 on the slide 36 of the pressure compensator 33 in turn counteracts the force of the spring 37 . Thus, the flow of pressure medium flowing out of the hydraulic motor 11 is kept constant even when the sequence is switched, and thus also the work feed backwards. At einfah render piston rod 12 'takes over the pressure compensator 33 through the sequence circuit together with the throttle function of the orifice 32 in the proportional directional control valve 15 also the counter function. An additional brake pressure valve with a large nominal size and an associated check valve for parallel bypassing can therefore be saved.

Is switched with retracting piston rod 12 'position-dependent from feed forward to rapid traverse backward according to arrow 55 in Fig. 1, the metering orifice 32 in the proportional directional control valve 15 is fully opened, the control valve 42 continues to take its parallel position 44 . The pressure compensator 33 also ensures a constant volume flow regardless 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 it is achieved that no leakage valve must be additionally arranged in this connection. This eliminates even with such leakage-oiled Venti len due to pressure fluctuations changing leakage oil flows, which could interfere with a constant Arbeitsvorschubgeschwin speed. The achievable, minimum working feed rate can therefore be chosen even smaller. This is particularly important if the viscosity of the pressure medium and thus the size of the leakage oil flows can change due to larger temperature fluctuations.

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

In the second device 60 , the functions for direction control and speed control combined in FIG. 1 in the proportional directional control valve 15 are now realized in two separate valves, namely the directional control in a 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 Ven valve, and the proportional throttle valve 62 only needs to control two ways, so that it builds considerably easier. At the proportional throttle valve 62 , the inlet connection 16 and the second consumer connection 23 are only required for the second control connection 26 , which is connected in a corresponding manner to the second control line 39 . The two working lines 22 and 24 are now connected directly to the 4/3-way valve 61 , so that the pressure compensator 33 and the proportional throttle valve 62 are in series with one another in the second working line 24 . A return line 49 is omitted, so that in the case of rapid forward and rapid reverse on the hydraulic motor 11 the pressure medium volume in each case flows out via the directional valve 61 to the tank 19 .

The mode of operation of the second device 60 corresponds analogously to that of the first device 10 , the corresponding magnets 63 and 64 on the switching directional valve 61 having to be excited for direction control for forward and backward on the hydraulic motor 11 and the speed control being taken over by the proportional throttle valve 62 , the associated one Proportionalma only works in one direction. The func tion of the switchable by means of the control valve 42 pressure compensator 33 remains unchanged.

Fig. 3 shows a part of a third device 70 , with which he can aim in a particularly simple and advantageous manner a start-free feed control. The third device 70 differs from the first device 10 according to FIG. 1 as follows, the same reference numerals being used for the same parts.

In the third device 70 another Proportionalwegeventil 71 is used, in which in the middle position 27, the second control port 26 has a cross connection 72 with the inlet port 16 connection. This special central position 27 can be achieved together with the switchable pressure compensator 33 , that at the start of a feed motion movement forward or backward, the slide 36 in the pressure compensator 33 always moves from its closed position into the control position instead of from the open position.

At the beginning of a forward feed movement, the proportional directional control valve 71 is in its central position 27 , and the 4/2 control valve 42 is in its cross position 43 . The pressure building up in the inlet connection 16 can now act via the cross-connection 72 , the second Steueran circuit 26 and the second control line 39 in the pressure chamber 35 and press the slide 36 of the pressure compensator 33 against the force of its spring 37 into a locked position. At the same time, the spring chamber 34 is relieved via the first Steuerlei device 38 in the central position 27 of the proportional directional control valve 71 to the tank 19 . At the start of the feed, the proportional directional control valve 71 switches in the direction of its cross position 28 ; the slide 36 in the pressure compensator 33 moves from the closed position into its control position and thereby avoids a start jump.

When working feed backwards, the proportional travel valve 71 and the control valve 42 are again in the same starting positions, namely the central position 27 and the cross position 43 . The pressure compensator 33 is therefore closed. At the start of the work feed backward, both valves 71 , 42 switch simultaneously into their parallel positions 29 and 44 , respectively, with the slide 36 in the pressure compensator 33 again moving from its closed position into the control position. A start jump is also avoided here.

Of course, changes to the shown devices are possible without departing from the spirit of the invention. The valves for the directional control and speed control functions can be designed both as directly operated and as piloted valves. The feed control is also not limited to the differential cylinder shown as a hydraulic motor, in whose place a working cylinder with the same size effective areas can be used in a circuit according to FIG. 2.

A circuit is particularly advantageous if a Dif ferential cylinder compared to FIG 2 is connected to the working lines 22 , 24 ; that is, the cylinder chamber 14 to the first ( 22 ) and the piston rod chamber 13 to the second working line 24 . Then the pressure compensator 33 takes over the counter position when the piston rod moves out. With a strongly changing load, z. B. with a piercing drill, this results in a reliable clamping. Even when the piston rod is retracting, rapid traverse and feed can be achieved. The counterbalance by the pressure compensator can be considerably stronger than with a counter pressure relief valve.

Claims (9)

1. Device for controlling a hydraulic actuating device, which has a double-acting hydraulic motor ( 11 ), from which two working lines ( 22 , 24 ) to a directional control valve ( 15 ; 61 ; 71 ) controlling the direction of the hydraulic motor ( 11 ), which on the other hand also a pressure medium source ( 17 ) and a tank ( 19 ) are connected, and with a current regulator formed from a measuring orifice ( 31 , 32 ) and a pressure compensator ( 33 ) for controlling the feed speed of the hydraulic motor ( 11 ), the measuring orifice ( 31 , 32 ) being adjustable is designed in the form of a proportional valve ( 15 ; 62 ; 71 ), the pressure difference of which can be fed to the pressure compensator ( 33 ) via control lines ( 38 , 39 ), the pressure compensator ( 33 ) acting as one of the directional control directional control valve ( 15 ; 61 ; 71 ) a separate 2-way valve is formed, and in which device in leading both to the pressure compensator (33) control lines (38, 39) a pressure compensator (33) 2-switching-position Steue rvalve ( 42 ), with which the connections to the pressure compensator ( 33 ) can be switched according to the different flow, characterized in that the pressure compensator ( 33 ) into the working line ( 24 ) between the hydraulic motor ( 11 ) and the proportional valve ( 15 ; 62 ; 71 ) that at least one ( 39 ) of the control lines ( 38 , 39 ) can be influenced in a controllable manner by the proportional valve ( 15 , 62 ) and that the control valve ( 42 ) is designed as a 4-way valve. 2. Apparatus according to claim 1, characterized in that a pressure valve ( 47 ) is connected as a counter-valve in the working line ( 22 ) not guided via the pressure compensator ( 33 ), to which a non-return valve ( 48 ) opening in the direction of the hydraulic motor ( 11 ) opens ) is connected in parallel. 3. Apparatus according to claim 1 or 2, characterized in that the proportional valve ( 62 ) from the directional control valve ( 61 ) for the directional control separate proportional throttle valve, which has at least one control connection ( 26 ) for one ( 39 ) of the control lines to the pressure compensator ( 33 ). 4. Device according to one of claims 1 to 3, characterized in that the proportional valve with the directional control directional valve ( 15 ; 71 ) combined is designed as a proportional directional control valve. 5. The device according to claim 4, characterized in that the proportional directional valve ( 15 ; 71 ) has two control connections ( 25 , 26 ) which are connected in parallel to the same connection of the control valve ( 42 ). 6. The device according to claim 5, characterized in that in the central position ( 27 ) of the proportional directional valve ( 71 ) one (26) of the control connections with the inlet connection ( 16 ) has connection and the control valve ( 42 ) the pressure compensator ( 33 ) to avoid initially controls a start jump. 7. Device according to one of claims 1 to 6, characterized in that the proportional valve ( 15 ; 62 ; 71 ) has a cross position ( 28 ) in which the pressure compensator ( 33 ) works as a downstream inlet flow controller and in which the pressure upstream of the orifice plate ( 31 ) is supplied in the proportional valve to the control line which loads the slide ( 36 ) of the pressure compensator ( 33 ) in the closing direction. 8. Device according to one of claims 1 to 7, characterized in that the directional control valve ( 15 , 71 ) for the directional control has a parallel position ( 29 ) in which the pressure compensator ( 33 ) works as an upstream discharge flow controller and in which the pressure downstream of the Measuring orifice ( 32 ) is fed in the proportional valve to the control line which loads the slide ( 36 ) of the pressure compensator ( 33 ) in the opening direction. 9. Device according to one of claims 1 to 8, characterized in that the pressure compensator ( 33 ) performs the counter-holding function in a moving piston rod during the working or rapid traverse feed forward of the hydraulic motor.