DE1426606A1 - Device for controlling hydraulic machines - Google Patents

Description

An apparatus for controlling hydraulic working machine The invention relates to an apparatus for controlling hydraulic working machine having at least one cylinder piston assembly for actuating a reciprocating movable operating means and a control slide associated with the throttling of the return flow into a tank, where the led to the spool pumping endruckleitung with a Actuator of the throttle member for the return to the tank is connected.

For example, dump trucks are such work machines known, in which the work equipment is the loading tub of the vehicle. at the task of such a loading tub is to keep it under control on the one hand overturning due to the pump pressure and lowering on the other hand.

It is known that there is a pressure relief valve in the control device is to be provided that - like an actuating piston surface of the throttle member - with the Pump discharge line - When the loading tray is lowered, the throttling of the return acts as a lowering brake.

A particular problem with such vehicles is that the Loading bath or a corresponding work equipment via a culmination point is tilted, so that it is then tended by its weight, the return side of the cylinder piston device and through the suction movement on the working side Reduce pump pressure.

Another working machine for which the invention is suitable, is for example a hydraulic lifting device, possibly a lifting vehicle. at the problem of lowering braking occurs when the lifting device is lowered will. This is also effective in this embodiment during the permitted lowering Weight of the load in the sense that the return side of the cylinder piston assembly applied and the pressure side is relieved.

It is known to have two spool valves in such devices to assign special hydraulic control elements, namely on the one hand a pressure relief valve and on the other hand a control valve in the return. Both valves are on the pump pressure side in connection in such a way that the pressure relief valve is designed in a known manner and is acted upon by a spring in the closing direction, while the control valve of the return has a piston surface on one side to the Pump pressure line is connected. This control valve, which is only available in Opening or closing senses works, has a counter pressure spring.

In the starting position, i.e. in the position in which the working equipment is not operated, the pump is directly connected to the return, i.e. the 2-pump pressure line is fully relieved. In this respect, the control valve is also located in its closed position. If now the work facility, which is under considerable Load can stand, should be acted upon and the pump pressure line to the working side the cylinder piston device is connected, the pressure in the pump pressure line increases instantly to a very high value. If in this case, possibly too the pressure relief valve does not yet respond, but the pressurized holbenf1.che receives of the control valve lying in the reflux a strong load shock, so that this Valve is opened instantly to a considerable amount. This shock load leads to the return oscillation of the counter pressure spring, so that a certain oscillation in the hydraulic drive circuit is created. Furthermore, after exceeding the mentioned culmination point the effect that the valve member of the control valve even when the piston surface is relieved by the momentarily decreasing pump pressure is strongly acted upon, so that an unstable state also arises. Self if in this case the counter-pressure spring is made strong enough to reverse the flow to throttle or close what by the momentary reduction of the pump pressure is favored, there are also pressure oscillations in the hydraulic at this point System.

Similar conditions arise with lifting vehicles on the one hand Beginning of the lift and, on the other hand, when lowering the load. Especially with lifting vehicles It is important from he that at the beginning of the lowering by switching the control slide no vibrations in the hydra, ulisehen system arise because such, in particular under heavily increased loads, convert into vibratory movements of the Zastträgers can.

Another disadvantage of the known design is that for the pressure relief valve and the throttle device require different cylinder bores become, which on the one hand is expensive and on the other hand to a considerable size leads. Furthermore, there is the possibility that under certain adverse circumstances the pressure relief valve can open regardless of the setting of the throttle device, so that opposing influences occur.

The invention is based on the object of eliminating these disadvantages and to create a device that is both space-saving and with fewer units is carried out when performing the same tasks and which, on the other hand, also apply one uniform and essentially pressure fluctuation-free control of the hydraulic Circle leads.

According to the invention, this object is achieved in that this actuator in the starting position of the control slide under the action of the pump pressure to connect the pump pressure line to the return, actuated depending on the pressure and the pump pressure line is connected to the return to the tank via a throttle section is, and that a pressure relief valve is assigned in a manner known per se, the is connected to the pump pressure line.

By this embodiment, the throttle member is at the beginning of a Working movement already in a deflected position, so that for the passage a return to the tank no sudden opening movement is required. That Throttle body is adapted to the respective conditions and corresponding to the pressure established in the pressure line both in terms of a further Opening as well as in the sense of an increasing throttling displaceable: This is an automatic adjustment to the respective load conditions is guaranteed.

According to a particularly preferred embodiment of the invention are to solve the former point of view in the task, the throttling of the Return and the pressure relief valve designed as a unit and in only one cylinder bore arranged. This at the same time becomes one in mutuality Dependency relationship standing effect of the throttle element and the pressure relief valve reached, so that no Effects can occur that are not coordinated with one another.

Acts according to a further advantageous embodiment of the invention the actuator for the unit with two springs of different characteristics together, one of which as a return throttle or lowering brake spring with relatively smaller Spring constant is executed, while the other that only after a certain Shifting of the actuator can be acted upon, has a larger spring constant. Through this it is achieved that a resulting counter-pressure spring characteristic for the actuator by means of two springs is provided with a kink, behind which the characteristic when shifting further of the actuator has a greater steepness than before this kink. This is advantageous the working area with greater steepness reserved for overpressure relief, while the throttling in the area with a lower steepness of the spring characteristic lies. Because these work area sections are not parallel, but according to the invention are connected in series, there is the possibility of the transition from one To exploit the area in the other for special tax purposes.

In the preferred embodiment of the invention, a piston with a central bore is provided as the actuator, in which an overpressure control piston can be displaced. One end face of the actuator is in a certain pressure range ten plants connected to the pressure side of the pump port, in which operating pressure range and the other side of the excess pressure-control piston is located on the pump pressure. Thus, the overpressure control piston is then relieved in this operating pressure range associated with the throttling of the return flow.

According to a further embodiment of the invention is in the actuator a channel that carries the pump pressure to the end face of the actuator is arranged, which operating ports cooperating with various control surfaces of the cylinder has, one of which relieves the front side when a certain limit is exceeded Pump pressure causes, with the other shut off at the same time from the pump pressure is, while the middle bore of the actuator with the overpressure control piston is due to the pump pressure. This is the transition to different operating pressure ranges guaranteed with different spring characteristics. In the execution of the as Actuator serving piston, the invention provides that an axial Druckleitungsbohrung.in the actuator has two radial branches, each of which is in the starting position a circumferential groove located at the pump pressure are connected, with displacement of the actuator blocked in the sense of opening the throttle of a branch is and with increasing pump pressure in the Area of a return chamber while the other branch is then shut off.

An advantageous embodiment of the invention has for the actuator two concentric springs, one of which acts as a brake spring between the one in the starting position located actuator and a support bearing is arranged, while the other is supported at its end associated with the actuator in an abutment which at a distance from the actuator and after a certain movement of the Actuator can be acted upon by this. This abutment is expediently adjustable, in order to give the assigned spring an adjustable preload.

An essential feature of the invention is the combination of one As a unit in a cylinder, throttling of the return, i.e. in a special application of a lowering brake and a pressure control valve with a Multiple control device within a housing, the multiple control device -a or can have several control spools.

The invention is explained below on the basis of exemplary embodiments, which are shown in the drawing. These show: FIG. 1: a plan view on a device with a multiple control slide and one Unit according to the invention for the throttle element and the pressure control valve in Cut.

FIG. 2: an end view of FIG. 1, seen from the right, where in addition on the actuator of the control slide a control template shown in section and the attachment member for an operating handle is attached, FIG. 3 : a section along the line III - III in FIG. 2.

The device is described using an embodiment shown in FIG a housing 1, a unit 2, which the throttle member 'and the overpressure control valve comprises, as well as a control slide 3. This housing thus has two cylinder bores, 4 for the unit and 5 for the spool. in the latter hole is a bushing 6 arranged, in which the actual control slide 7 is located. In the Figure are for a working device, which is supported by a cylinder-piston device, not shown can be actuated, only two connections 8, 9 are provided, which are in different sides of the cylinder of the working device open. It goes without saying that in the housing, For example, on the upper side, not shown in FIG. 1, two further connections can be arranged for a further cylinder piston device another work facility are provided. The arrangement shown is for two such tools are provided, one of which is a dump truck and the other an additional device, for example a support device for the vehicle, on the tilting device is. These relationships are not yet discussed in more detail because it involves i.e. with the simultaneous control of several work equipment or the type the control of several work equipment, not about the essential characteristics of the invention. The explanation is given in the following only taking into account the connections 8, 9 given for a work device.

A connection piece 10, which is the pressure connection, also opens into the housing or the pressure line for the pump is. this is indicated by dashed lines Openings 11, 12, with a control chamber 13 of the socket 6 and a connecting channel 14 in connection, which leads to the socket 15 of the unit 2. The control spool 7 has a central bore 16, which passes through two diametrical hadial bores 17, 18 connected to. The connecting channels passing through the socket 6 to the control slide are denoted by 19 and 20. The one formed in the circumferential direction in the socket Control room 13 is assigned a corresponding control room 21 relatively close. The control chamber 21 is via a connecting bore 22 with a corresponding one radial control chamber 23 in the unit 2 in connection.

The control slide 7 has a control groove 24 formed in the circumferential direction, which connects the control spaces 13 and 21 in the initial position shown, the control space 21 being connected to the radial bores 17 through an extension 25 to which a recess 26 in the slide is assigned.

Furthermore, in the control slide 7 there is a circumferential direction Control recess 27 arranged, optionally with the radial connecting channels 19, 20 can be associated. The control recess is in the socket assigned a radial connection 28, which is connected to a newspaper 29 via a check valve 30 communicates. (Fig. 3). This check valve 30 opens to the radial Connection 28. The Rückschlagveiitil 30 consists of a valve body 31, the under Load of the spring 32 is and by means of the bores 33, 34 of the hydraulic Nedium can flow through. The newspaper 29 continues through a cross hole 35 with the connecting channel 14 in connection.

The ends of the newspapers and channels are closed with plugs.

Since the connecting channel 14 in the manner described with the pump connection 10 is in connection, it follows that the radial connection 28 with the pump pressure is connectable. It can be seen that the control recess 24 and the control groove 27 with axial incisions at their ends are provided that are in Act in a known manner as a throttle section .. The central bore 16 is at its left end of the mouth closed by a plug 36 as well as the socket the left has a closure member 37. On the right is an actuating linkage on the control slide 38 arranged, which is articulated to the control slide by means of the pin 39 is. This is under the load of a spring 40 which is against a stopper 41 acts at the right end of the socket. According to FIG. 2, a is articulated on the linkage Actuating pin 42 arranged, which is adjustable in a shift gate 43, the is not shown in more detail in FIG. The socket 15 has a central bore 44,, ir'i which the actuator 45 is displaceable. The hole 4.4 is screwed in on the left Plug 46 closed and right open. In the area of the opening, the actuator has 45, which is designed like a piston, a step 47 on which an annular disc 48 seated. The continuation of the actuator is denoted by 49. The washer 48 forms an abutment of a so-called throttle spring 50, which on the other hand an annular projection 51 is supported, which on the front wall closure 52 of the Cylinder bore 53 of the housing rests. This cylinder bore takes the liner 15 on.

In the cylinder space on the right, ie in the area of the spring 50, another stronger spring 54 is arranged concentrically in the spring 50. This spring is on the one hand a resistance lager to verschlug 52 and on the other hand be on a Lagerschei- 55j which is arranged on a rod 56 with a thrust bearing 58th The rod 56 is led out through the lock 52 . It has a thread and a Stellsohraubenanordnung 579 which can make adjustable 54 Vorapannung the äeder to lead-out end. The Yederwiderlager 55 and the thrust bearing 58 may be the continuation 49 and a central abutment on the continuation in the presence position come to compress the spring 54th Before this system is reached, the actuator 45 must be moved a considerable distance to the right, ie the spring 54 must have already been compressed beforehand.

The connecting channel 14 continues through the socket 15 in an inwardly open annular groove 59. The annular groove is adjacent to a corresponding annular groove 60 which is connected to the connecting duct 14 or the continuation into the annular groove 59 through a duct 61 . The control chamber 23 is associated with an annular groove 62nd Furthermore , an inwardly open annular groove 63 is provided in the socket. The other annular groove is connected to the drain 64 to the tank. The annular groove 62 is assigned a control outlet 65 in the actuator that extends in the circumferential direction. This control chamber has a greater length than the annular groove 62. This control chamber 65 can be provided with throttle notches at its ends. In the actuator 45 is a. further control chamber 66, which extends in the circumferential direction and is located in the area of the annular grooves 59, 60.

In the actuator 45 there is an axial channel 67, which opens at the end face 68 and has two radial connections 69, 70. In the starting position, the radial connection 69 lies at the left end of the annular groove 60, while the radial connection 70 lies in the vicinity of the right end of the annular groove 59. The distance between the radial connections 69, 70 is selected so that when the actuator 45 is shifted to the right, the radial connection 7i5 is initially closed, while the radial connection 69 remains open. However, if this is closed at the socket 15 when the actuator 45 continues to move to the right, the radial connection 70 opens in the annular groove 62. At this moment, however, the annular groove 62 would pass through the control chamber 65 with the annular groove 63 and thus with the return 64- connected to the tank.

It should be noted that the control chamber 66 is connected to an inner bore 72 of the actuator 45 through q a radial bore 71. The control chamber 66 has such: that is length in the Ausgangsetellung with the annular groove 59 in connection which is situated on the Pumpendruok that it does not come with the annular groove 62 in connection: In the inner bore 72, a relief valve piston 73 is overall results, which is exposed to the front surface 68 and forms an engagement surface 74 at the right end. The shown reduction in circumference serves as a vibration inhibitor. The right bath * the overpressure control piston 73 is. a mating surface 75 is assigned which blocks the bore 72. For this purpose, an auxiliary punch can be used, for example (as shown).

In the starting position, which is shown, the connections 8, 9 are blocked by the control slide. The pump pressure passes through the connection 10 into the control chamber 13 and from there via the connecting channel into the annular groove 59. The control chamber 13 is at the same time connected by the control groove 24 to the control chamber 21 and thus in the manner described with the annular groove 62 transmitted through the annular grooves 59, 60 and the channel 67 on the left side of the actuator 45, which is moved under compression of the spring 50 to the right. As a result, the control chamber 65 comes into connection with the control groove 63 and thus with the return 64, so that the pressure from the pump is connected to the return via a throttle section at 76. The throttle section opens more or less depending on the level of the pump pressure. At the same time, the pump pressure reaches the right-hand side of the overpressure control piston 73 through the radial bore, so that this is relieved. If the control slide 7 is adjusted to the right, for example, the control recess 27 closes the pump pressure to the connection 9, while the connection 8 is connected via the radial bore 17 and the extension 25 to the control chamber 21, which through the connection 22 the annular groove 62 and the Throttle path connects to the outlet 64. The greater the resulting pump pressure, the more the throttle section is opened, while in the opposite case it can be closed.

If there is a higher level of overpressure at the pump, it migrates the actuator 45 so far to the right that the initially closed radial connection 70 opens into the annular groove 62, at the same time the radial connection 69 through the Web between the annular grooves 59, 60 is closed from the pump pressure. In this Moment the left end face 68 of the actuator is relieved of pressure. In order to but the pump pressure continued through the radial bore 71 acts on the right End of the overpressure control piston 73, so that the reaction movement to a further Shifting the actuator q-5 to the right leads. This then makes the connection between the annular groove 59, which is connected to the pump or the connection piece 10 is connected to the control room 23, so that the pump pressure to your return got. The connection between the annular groove 59 and the control chamber 22 takes place, for example through the control room 66.

During this displacement of the actuator, the continuation 49 or an abutment arranged in its area comes into contact with the bearing disk 55 or with the thrust bearing 58, so that the stronger spring 54 is compressed. Since the tension thereof is adjustable, it can be seen that the spring 50 alone can initially also act in the overpressure region, or that the spring 54 , for example, can already be inserted before entering the overpressure region. In this way, can be divided into Advantageous ter way achieve certain characteristics that are lastabhän- gig and provide additional security. The invention therefore creates, in the manner described, on the one hand a throttling of the return flow or a lowering brake with a kinked characteristic or. In another particular embodiment, a pressure relief valve which also has a kinked characteristic , a counterforce with a higher constant being set in the area of the higher pressure.

It goes without saying that throttle notches can be provided in the usual way on control edges, as already mentioned in some cases. It can be seen that the invention achieves the underlying object, the possibility of providing differently designed characteristics for the individual operating areas of the unit being emphasized in addition to the above remarks. This can be of particular importance for a lowering brake, for example , if a certain acceleration is to occur during a prolonged lowering movement, which is safely absorbed by a counterforce that increases more rapidly from a certain point. In the other setting , a relatively easy - but only after the return throttling has been used - an appealing overpressure valve is created which, however, finds a stronger counterforce with increasing overpressure.

Claims (1)

1. A device for controlling hydraulic working machine having at least one cylinder-piston device for loading actuation of a reciprocable working device and an associated a control slide throttling the return flow into a tank, where the led to the spool Pumpendruckleitungmit an actuator of the throttle member for the return to the tank is connected characterized in that said manipulated member (45) in the starting position of the control slide (7), when acted upon by the pump pressure to connect the pump pressure line to the return pressure dependent basis actuated and the pump pressure line via a throttle section (76) with the return (64) is connected to the tank, and that an excess pressure valve is arranged in conces- manner known per se, which is connected to the pump discharge line. 2. Apparatus according to claim 1, characterized in that the throttling of the return and the pressure relief valve are designed as a unit and are arranged in only one cylinder bore (53) . 3. Apparatus according to claim 2, characterized in that the throttling of the return and the pressure relief valve are connected in series so that the latter only becomes effective after the operational throttling of the return has been brought into effect in its entire setting range . 4. Apparatus according to claim 1 and 2, characterized in that the actuator (45) for the unit cooperates with two springs ( 50, 54) of different characteristics, one designed as a return throttle or lowering brake spring (50) with a relatively small spring constant is, while the other (54), which can only be acted upon after a certain displacement of the actuator (45) , has a larger spring constant . 5. Device according to one of claims 1 to 4, characterized in that a piston with a central bore (72) is provided as the actuator (45) , in which an overpressure control piston (73) is displaceable , and that an end face (68 ) of the actuator is connected to the pressure side of the PUapeneinsohlusses (10) in a certain operating pressure range, in which operating pressure range the other side of the overpressure control piston (73) is also at the pump pressure . 6. Apparatus according to claim 5, characterized in that in the actuator (45) a the pump pressure to the end face of the actuator (45) leading channel (67) is arranged which has cooperating with different control surfaces of the cylinder operating openings (69, 70) , of which one (70) relieves the end face (68) when a certain pump pressure is exceeded , the other (69) being shut off from the pump pressure at the same time, while the central bore (72) of the actuator (45) with the The overpressure control piston (73) is at the pump pressure. 7. Apparatus according to claim 5, characterized in that the DAB an axial pressure line bore (67) in the actuator (45) has two radial branches (69, 70) which in the initial position, respectively one The pump pressure Lie constricting circumferential groove (59, 60 ) are connected, and that when the actuator (45) is moved in the sense of opening the throttle, one branch (70) is blocked and when the pump pressure increases it reaches the area of a return chamber (62), while the other branch (69 ) is locked. B. Apparatus according to claim 4, characterized by two concentric springs (50, 54), one of which is arranged as a brake spring (50) between the located in the starting position actuator (45) and a support bearing (51), while the other ( 54) at its-the actuator (45) associated end in an abutment (55, is supported 56) spaced from the actuator (45) and after a certain movement of the actuator from this is beaufsohlagbar. 9. Apparatus according to claim 8, characterized in that the abutment (55, 56) is adjustable in order to give the other spring (54) a bias . 10. The apparatus of claim 1, 4, and 9, characterized in that larger for the actuator by means of two springs (50, 54), a resultant back-pressure Bedercharakteristik is provided with a crease provided, behind which the characteristic element of the manipulated upon further displacement Has steepness than before this kink. 11. Apparatus according to claim 9 and 10, characterized in that by adjustment of the abutment (55, 56) in the operating region for throttling or in the operating range for the pressure relief valve can be laid the bend of the characteristic and either a throttling with a counter-force, which has a kinked characteristic or a pressure relief valve with a kinked characteristic is provided . 12. Device according to one of claims 1 to 11, characterized by the combination of a overall ausgefüh as a unit (2) in a cylinder: appliance Icten Senkbremse and a Überdrnckateuerventils with a Mehrfachsteuer- (3) in a housing.