EP1400313B1 - Hydraulically operated ratchet spanner with a double-acting hydraulic cylinder/piston drive - Google Patents

Abstract

The ratchet screwdriver (12) is operated by the piston rod (15) of a double-action hydraulic piston-cylinder drive, the hydraulic oil supplied via a hydraulic pump unit (1) with cogwheel pump (20) and a radial piston pump (21) operated by a pump motor (4), the cogwheel pump providing a relatively large feed quantity for each motor rotation and the piston pump providing a relatively small feed quantity for each motor rotation. The working stroke and the return stroke of the piston rod are effected by reversing the rotation direction of the pump motor via a pump motor control (22), with automatic adjustment of the volumetric flow.

Description

The invention relates to a hydraulic ratchet wrench with a double-acting Hydraulic cylinder-piston drive according to the preamble of the claim 1, which is known from the document DE 37 19 893 A. In a well-known hydraulic ratchet wrench with a double acting hydraulic cylinder piston drive is a piston as Disk piston slidably guided in the hydraulic cylinder, the one tight the hydraulic cylinder led out piston rod for ratchet operation having. In the hydraulic cylinder is a working stroke by the displaceable piston as a high pressure chamber on a piston side of the piston and a Rückhubkammer as a low pressure chamber on the piston side with the piston rod educated.

The well-known hydraulic ratchet wrench also includes a two-stage Hydraulic pump assembly with a gear pump and a piston pump. The gear pump and the piston pump are by means of a via a Pump motor control controllable pump motor through its output shaft drivable, the gear pump due to their construction a relative large flow hydraulic oil per engine revolution up to a pressure of can pump about 100 bar and the piston pump in contrast, a relative small flow per engine revolution, however, up to much higher Press to pump is able. The pump assembly is via a hydraulic control unit connected to the working stroke chamber and the Rückhubkammer.

This known pump arrangement is via the hydraulic control unit so controlled that in a first phase of a screwing process, in which in the Ratchet unit still no or only a small torque is applied the working stroke chamber pumping over the fast and with large delivery volume Gear pump is filled. In a second phase at the end of the screwing process, if a high screw-on torque is to be applied, is decoupled by the hydraulic control unit, the gear pump and the Piston pump switched on, which then with this in the Arbeitshubkammer pumped with high pressure. The necessary switches in the hydraulic lines in particular also the switching from Vor- Return to the hydraulic cylinder lifting chambers follows through expensive, susceptible to interference Valves, in particular by solenoid valves, which have their own power supply need. This results in a relatively large energy requirement for the arrangement in particular for the drive motor, which in turn to an unfavorable large heat development in the hydraulic oil leads. Therefore, it is in these known systems, the hydraulic oil with expensive coolers required consuming cool and / or heavy and large oil tanks with a large To use hydraulic oil volumes that make handling difficult.

The object of the invention is a generic hydraulic ratchet wrench with a double-acting hydraulic cylinder-piston drive so educate that a cheaper, more reliable and easier Construction in combination with low weight and small dimensions with low energy consumption is possible.

This object is achieved with the features of claim 1.

According to claim 1, a first gear pump port is provided with a working-stroke chamber hydraulic oil passage with the working chamber and a second Gear pump connection with a return stroke hydraulic oil pipe with connected to the Rückhubkammer.

The working-stroke chamber hydraulic oil passage is at a first intake port via a first intake manifold with a first intake check valve and the return stroke hydraulic oil passage at a second Intake connection point via a second intake manifold with a second suction check valve with the hydraulic oil volume of an oil tank connected.

Between the first suction connection point and the working stroke chamber is a high-pressure check valve with a blocking action in the direction of the first Intake connection point arranged in the working stroke chamber hydraulic oil line.

The piston pump is designed as a radial piston pump, possibly also different constructed piston pumps can be used with appropriate effect. Preferred is an embodiment of a radial piston pump with three against each other staggered small pump cylinders, the pistons be driven for example via an eccentric disc. The radial piston pump is at a piston pump suction inlet through a piston pump suction line connected to the hydraulic oil volume and to a piston pump delivery outlet through a piston pump delivery line between the high pressure check valve and the working stroke chamber with the working stroke chamber hydraulic oil passage connected.

Furthermore, a hydraulic oil return line leading into the oil tank is provided. This hydraulic oil return line is via a pressure-controlled low-pressure limiting valve between the first intake connection point and the high pressure check valve with the working stroke chamber hydraulic oil line connected, wherein a return flow of hydraulic oil from the working-stroke chamber hydraulic oil line to the oil tank when reaching a certain low pressure is releasable.

The hydraulic return line is also over by a function of a pressure in the return stroke hydraulic oil pipe pressure-controlled Entsperr-check valve with reverse direction in the backflow between the High-pressure check valve and the working stroke chamber with the working-stroke chamber hydraulic oil line connected.

The pump motor is equipped with the pump motor control for a working stroke A direction of rotation can be controlled, so that at the first gear pump connection the delivery outlet and at the second gear pump connection the suction inlet lies. For a return stroke, however, the pump motor to a reverse direction controllable, so that then at the first gear pump connection the suction inlet and at the second gear pump connection the delivery outlet lies. Due to the structure of the radial piston pump promotes this in each of the driving directions in the same conveying direction. Possibly. are also in the direction of rotation and conveying direction reversible rotary element pumps with used other rotary elements than in a gear pump, provided they have a corresponding effect.

With the above arrangement is advantageously achieved that at the beginning of a Working strokes the gear pump with a large flow of, for example up to 6 liters per minute causes a fast piston feed, wherein also the delivery volume of the radial piston pump is switched on. to required associated emptying the return stroke this is fluid with the other acting as a suction port gear pump port connected. Because of the volume of the piston rod, the in the working stroke chamber inflowing hydraulic oil volume greater than that the return stroke chamber displaced hydraulic oil volume is can the gear pump the differential volume across the second intake manifold and the second Suction check valve still suck.

After reaching a certain set on the low-pressure relief valve Low pressure, for example, of 70 bar opens this, causing the Gear pump then promotes via the hydraulic oil return line into the oil tank. In addition, the high pressure check valve and the radial piston pump closes promotes with smaller flow of, for example, up to 0.6 liters per minute in a second screw phase in the working stroke chamber after for a high screwing torque high pressures of for example up to 700 bar are reachable. The resulting flow path switches take advantage of automatic, so that no externally controlled solenoid valves required are.

For a return stroke, the pump motor for an opposite direction of rotation controlled, so that the gear pump also in opposite Direction promotes. As a result, hydraulic oil is pumped into the return stroke chamber, over the open Entsperr-check valve, the Arbeitshubkammer is open for a return flow of hydraulic oil to the oil tank. The relative low flow rate of the radial piston pump is the return flow volume added. A high pressure build-up in the return stroke through the Radial piston pump is not possible with this arrangement. Becomes advantageous thus achieved a quick return of the piston or the piston rod. For the return stroke is thus only a reversal of the engine in his Running direction required, with the valves used in the arrangement suitable and automatically adjust without external control. Usual gaskets on the piston are high pressure resistant only from the Arbeitshubkammerseite. With the present arrangement this is taken into account, since in the return stroke chamber only the gear pump with maximum pressures of approx. 100 bar is effective, so that a cuff is achieved.

In contrast to the prior art, in which a changeover of power stroke on return stroke by several expensive and susceptible and externally controlled Valves is done, here is just a control to reverse the direction of rotation the pump motor required, in which case the valves used set properly in the correct function and without external energy. Of the Structure of the arrangement according to the invention is therefore much simpler, less expensive, more compact and lighter weight. In particular, a small one Oil tank volume possible and the hydraulic oil heats up operationally fewer.

With the features of claims 2 and 3 is also an advantageous safety pressure limitation both in the high pressure range and in the low pressure range possible.

Gear pumps with the features of claim 4 with a maximum Delivery pressure of about 100 bar and, for example, a flow rate of 0-6 Liters per minute are commercially available. When using such a gear pump is an operation of the arrangement in the low pressure range of up to 70 bar expedient and has proven to be suitable in practical testing.

Also radial piston pump with the features according to claim 5 with a maximum discharge pressure of about 700 bar are commercially available and for the proposed arrangement well suited.

In a specific embodiment according to claim 6 may be appropriate due the piston rod volume, the ratio between the Arbeitshubkammervolumen and the Rückhubkammervolumen to about 3: 1 dimensioned become. With the proposed arrangement is a balance of therefore required different volume flows automatically without targeted Control interventions possible.

For the pump motor control in conjunction with the control of the Screwing are known measures available: The Pump motor control, in particular the right-left rotation control can be manually or automatically activated, the screwing manually, time-dependent or working pressure-dependent as well as torque-dependent controllable can be executed. A current screwing torque as control parameter can in a conventional manner directly via a torque transducer or indirectly over the current assigned working pressure or the current power consumption of the pump motor can be determined.

Depending on the circumstances and applications, the pump motor can after Claim 8 be an electric motor, an air motor or a hydraulic motor.

Reference to a drawing, the invention is explained in detail.

Fig. 1

eine perspektivische Darstellung einer Hydraulikpumpenanordnung mit Pumpenmotor.

Fig. 2

einen Hydraulikschaltplan für die Hydraulik-Pumpen-Anordnung mit angeschlossenem Hydraulikzylinder und einer schematisch dargestellten Schraubratsche.

Fig. 3

den Schaltplan nach Fig. 2 mit eingezeichneten Volumenströmen in einer ersten Phase eines Arbeitshubs.

Fig. 4

den Schaltplan nach Fig. 2 mit eingezeichneten Volumenströmen in einer zweiten Phase eines Arbeitshubs.

Fig. 5

den Schaltplan nach Fig. 2 mit eingezeichneten Volumenströmen bei einem Rückhub und

Fig. 6

ein Diagramm aus dem die Größe des Arbeitshub-Volumenstroms bei ansteigendem Arbeitsdruck ersichtlich ist.

Show it:

Fig. 1

a perspective view of a hydraulic pump assembly with pump motor.

Fig. 2

a hydraulic circuit diagram for the hydraulic pump assembly with connected hydraulic cylinder and a screw ratchet shown schematically.

Fig. 3

the circuit diagram of FIG. 2 with drawn volume flows in a first phase of a power stroke.

Fig. 4

the circuit diagram of FIG. 2 with drawn volume flows in a second phase of a power stroke.

Fig. 5

the circuit diagram of FIG. 2 with drawn volume flows at a return stroke and

Fig. 6

a diagram showing the size of the working stroke volume flow with increasing working pressure.

In Fig. 1, the structure of a hydraulic pump assembly 1 of a hydraulic ratchet wrench shown. An oil tank 2 for hydraulic oil is through a cover plate 3, on which a pump motor 4 with a vertical motor output shaft is mounted. In the oil tank 2 are a (not visible here) gear pump and a radial piston pump disposed from the engine output shaft are driven. On the cover plate 3 is also a hydraulic control unit 5, the circuit configuration explained in connection with FIG becomes. To the hydraulic control unit 5 is a high pressure gauge. 6 connected. There are also actuations for shut-off valves and control valves recognizable. From the hydraulic control unit 5, a power stroke hydraulic oil pipe lead 7 and a return stroke hydraulic oil passage 8 to a not shown hydraulic cylinder 9. In addition, a tank level indicator 10 and a tank vent 11 are shown.

In Fig. 2 is schematically and in conjunction with a hydraulic circuit diagram a hydraulic ratchet wrench 12 is shown. In a hydraulic cylinder 13 is a piston slidably received as a disc piston 14, wherein a Piston rod 15 or possibly an extension in a only schematically indicated Screw ratchet 16 engages the actuation. At the left side of the piston is a Arbeitshubkammer in the hydraulic cylinder 13 and on the right Piston side formed a return stroke chamber 18, in which also the piston rod 15 is guided displaceably. The hydraulic cylinder 13 with the associated Divide and the screw ratchet 16 form a unit 19 via flexible Hydraulic lines connected to the hydraulic pump assembly 1 shown in FIG is.

In the oil tank 2, the gear pump 20 and the radial piston pump 21 are added, driven jointly by the output shaft of the pump motor 4 become. The pump motor 4 is powered by a pump motor controller 22 operated to the example of a manual actuation unit 23 and a working pressure line 24 are connected for input of control parameters. The hydraulic circuit for the hydraulic control unit 5 is from the frame 25th framed, from which the high-pressure gauge 6 protrudes.

A first gear pump port 26 is via the working-stroke chamber hydraulic oil passage connected to the Arbeitshubkammer 17 in the end region. On the other hand, a second gear pump port 27 is connected to the return stroke hydraulic oil passage 8 is connected to an end portion of the return stroke chamber 18.

The working-stroke chamber hydraulic oil passage 7 is at a first suction port point 28 via a first intake manifold 29 with a first intake check valve 30 connected to the hydraulic oil volume of the oil tank 2. The return stroke hydraulic oil passage 8 is at a second intake port 31 via a second intake manifold 32 via a second intake check valve 33 is connected to the hydraulic oil volume of the oil tank 2.

Between the first intake connection point 28 and the working stroke chamber 17 is a high pressure check valve 34 having a blocking action in the direction of the first intake port 28 in the working-stroke chamber hydraulic oil passage 7 arranged.

The radial piston pump 21 has a piston pump suction inlet 35, with a piston pump suction line 36 with the hydraulic oil volume of the Oil tanks 2 is connected. From a piston pump delivery outlet 37 leads a piston pump delivery line 38 to a port with the working-displacement hydraulic oil passage 7 between the high pressure check valve 34th and the working stroke chamber 17. In the oil tank 2 also performs a hydraulic oil return line 39. This hydraulic oil return line is via a low pressure relief valve 40 with the working-stroke chamber hydraulic oil pipe 7 between the high pressure check valve 34 and the first intake port 28 connected.

In addition, the hydraulic return line 39 via a druckvorsteuerbares Unlock check valve 41 with the working-chamber hydraulic oil pipe 7 between the high pressure check valve 34 and the Arbeitshubkammer 17th connected. The unlocking check valve 41 has a blocking effect in Return flow direction and opens in response to a pressure in the Rückhubkammer hydraulic oil line 8, including a corresponding pressure control line 42 is guided from there to Entsperr-check valve.

Between the working-stroke chamber hydraulic oil passage 7 and the hydraulic oil return passage 39, a high pressure relief safety valve 43 is connected. Accordingly, between the Rückhubkammer hydraulic oil line. 8 and the hydraulic oil return line 39, a low pressure limiting safety valve 44 switched.

In Fig. 3, the hydraulic circuit of FIG. 2 (without screw ratchet 16 and engine control unit 22) shown with drawn volume flows in a first phase of a workhub. For this purpose, the pump motor 4 with a clockwise rotation (arrow 45), whereby at the first gear pump connection 26 the delivery outlet and the second gear pump connection 27, the suction inlet of the gear pump 20 are formed. This sucks the Gear pump 20 with high capacity hydraulic oil from the Rückhubkammer 18 via the Rückhubkammer hydraulic oil line 8 and pumps this in the Arbeitshubkammer 17. Because because of the piston rod 15 during the shift of the piston 14 less hydraulic oil from the Rückhubkammer 18th is displaced than is to be filled in the Arbeitshubkammer 17, sucks the gear pump 20 the difference volume additionally at least partially over the second intake manifold 32 and thereby opening the second intake check valve 33 on. Next is of the follower radial piston pump 21st via the piston pump suction line 36 and the piston pump delivery line 38 a relatively small flow of hydraulic oil in the Arbeitshubkammer 17 pumped. In this first phase, the high pressure check valve 34 open.

In Fig. 4, the second phase of a power stroke is shown, in which the Arbeitshubkammer 17 already largely filled with hydraulic oil and accordingly the Piston rod 15 is extended far. After reaching a low-pressure relief valve 40 set low pressure of 70 bar in the connected Working stroke chamber hydraulic oil line 7 below the reverse direction of the high pressure check valve 34 opens the low pressure relief valve and the gear pump 20 runs without further connection to the working stroke chamber 17, the line with the low pressure relief valve 40 acts as a short-circuit line to the hydraulic oil return line 39. The above the high pressure check valve 34 with the piston pump delivery line 38 connected radial piston pump 21 while pumping with less Delivery but with the possibility of high pressure build-up further into the working stroke chamber 17, wherein the high-pressure check valve 34th closed is. By this Nachpumpen with the radial piston pump 21st can with the piston rod 15 a high screwing torque in the second Phase of screwing be generated.

After completion of the bolting process (possibly even if several successive piston rod strokes in the first phase of the screwing process be required), the piston 14 and the piston rod 15 be returned. The corresponding volume flows are in Fig. 5 shown. For this, the pump motor 4 is to be reversed to counterclockwise (Arrow 46). As a result, the suction inlet is at the first gear pump connection 26 formed for an intake via the first connecting piece 29 and on second gear pump port 27 is the delivery outlet, d. H. the conveying direction the gear pump 20 is due to the reversal of the direction of Pump motor 4 also vice versa.

This is via the return stroke hydraulic oil pipe 8 with the gear pump 20 hydraulic oil pumped with high flow rate in the return stroke chamber 18. In addition, hydraulic oil flows out of the working stroke chamber 17 via the working-stroke chamber hydraulic oil line 7 above the closed High-pressure check valve 34 via the bypass line with the druckvorsteuerbaren Unlock check valve 41 and the hydraulic oil return line 39 in the oil tank 2 from. The unlocking check valve 41 is because the pressure rise in the Rückhubkammer hydraulic oil line 8, which is supplied via the pressure control line 42 to the unlocking check valve, open. In the return stroke chamber 18 thus occurs here at best by the Low pressure limiting safety valve 44 to 70 bar limited pump pressure the gear pump on.

The radial piston pump 21 works due to the construction, even with the left-hand rotation of the pump motor 4 in the same conveying direction, so that via the piston pump delivery line 38 the piston pump delivery is promoted. There but this is low compared to the flow rate of the gear pump 20 this easily without disturbing the return stroke from the Arbeitshubkammer 17th added flowing hydraulic oil and also via the hydraulic oil return line 39 fed to the oil tank 2.

From the diagram in Fig. 6 it can be seen that up to a working pressure of about 70 bar substantially the gear pump 20 for a fast working stroke the piston 14 acts, with reference to the engine speeds also indicated It can be seen that the engine speed and thus also the delivery rate the gear pump 20 with increasing back pressure of example 3000 revolutions per minute to about 400 revolutions per minute sinks. At about 70 bar then the gear pump 20 from the Arbeitshubkammer uncoupled and the radial piston pump 21 takes over the pumping process in the Arbeitshubkammer 17. As with the radial piston pump 21 only relatively little Volume is promoted per engine revolution, the load on the engine decreases Pump motor 4, so that its speed back to, for example, 3000 Rotations per minute increases, whereby the radial piston pump 21 initially the drawn still has relatively high capacity. At about 200 bar the delivery rate drops as well as the speed of the pump motor 4, then about with a flow rate of 0.35 liters per minute to the maximum achievable pressure of approx. 700 bar can be pumped on.

Claims (8)

1. Hydraulically operated ratchet driver (12) with a double-acting hydraulic cylinder/piston drive,
   having a piston (14) which is displaceably guided in the hydraulic cylinder (13) and has a piston rod (15), led tightly out of the hydraulic cylinder, for the ratchet actuation,
   having a working-stroke chamber (17) in the hydraulic cylinder as high-pressure chamber on one piston side and having a return-stroke chamber (18) as low-pressure chamber on the piston side with the piston rod,
   having a hydraulic pump arrangement (1) with a gear pump (20) and a piston pump (21),

   the gear pump (20) and the piston pump (21) being drivable by means of the output shaft of a pump motor (4) which can be controlled with a pump-motor control (22), and the gear pump pumping a relatively large delivery quantity of hydraulic oil per motor revolution, and the piston pump pumping an, in contrast, relatively small delivery quantity per motor revolution, and

   the pump arrangement (1) being connected via a hydraulic control unit (5) to the working-stroke chamber (17) and the return-stroke chamber (18),

      characterized

   in that a first gear-pump connection (26) is connected by a working-stroke-chamber hydraulic-oil line (7) to the working-stroke chamber (17), and a second gear-pump connection (27) is connected by a return-stroke-chamber hydraulic-oil line (8) to the return-stroke chamber (18),

   in that the working-stroke-chamber hydraulic-oil line (7) is connected to the hydraulic-oil volume of an oil tank (2) at a first intake connection point (28) via a first intake connection piece (29) having a first intake check valve (30), and the return-stroke-chamber hydraulic-oil line (8) is connected to the hydraulic-oil volume of the oil tank (2) at a second intake connection point (31) via a second intake connection piece (32) having a second intake check valve (33),

   in that a high-pressure check valve (34) having a blocking action in the direction of the first intake connection point (28) is arranged in the working-stroke-chamber hydraulic-oil line (7) between the first intake connection point (28) and the working-stroke chamber (17),

   in that the piston pump, in the manner of a radial piston pump (21), is connected to the hydraulic-oil volume at a piston-pump suction inlet (35) by a piston-pump suction line (36) and is connected to the working-stroke-chamber hydraulic-oil line (7) at a piston-pump delivery outlet (37) between the high-pressure check valve (34) and the working-stroke chamber (17) by a piston-pump delivery line (38),

   in that a hydraulic-oil return-flow line (39) leading into the oil tank (2) is provided,

   in that the hydraulic-oil return-flow line is connected to the working-stroke-chamber hydraulic-oil line (7) between the first intake connection point (28) and the high-pressure check valve (34) via a low-pressure-limiting valve (40), it being possible for a return flow to be released with the low-pressure-limiting valve (40) when a certain low pressure is reached,

   in that the hydraulic-oil return-flow line (39) is in addition connected to the working-stroke-chamber hydraulic-oil line (7) between the high-pressure check valve (34) and the working-stroke chamber (17) by a pilot-controlled check valve (41) which can be pilot-controlled as a function of a pressure in the return-stroke-chamber hydraulic-oil line (8) and has a blocking action in the return-flow direction,

   in that the pump motor (4) can be activated for a working stroke with one direction of rotation by the pump-motor control (22), so that the delivery outlet is formed at the first gear-pump connection (26) and the suction inlet is formed at the second gear-pump connection (27), and in that the pump motor (4) can be activated for a return stroke with an opposite direction of rotation, so that the suction inlet is then formed at the first gear-pump connection (26) and the delivery outlet is then formed at the second gear-pump connection (27), the radial piston pump (21) delivering in the same delivery direction in both directions of rotation of the pump motor (4).
2. Hydraulically operated ratchet driver with a double-acting hydraulic cylinder/piston drive according to Claim 1, characterized in that a high-pressure-limiting safety valve (43) is connected between the working-stroke-chamber hydraulic-oil line (7) and the hydraulic-oil return-flow line (39).
3. Hydraulically operated ratchet driver with a double-acting hydraulic cylinder/piston drive according to Claim 1 or Claim 2, characterized in that a low-pressure-limiting safety valve (44) is connected between the return-stroke-chamber hydraulic-oil line (8) and the hydraulic-oil return-flow line (39).
4. Hydraulically operated ratchet driver with a double-acting hydraulic cylinder/piston drive according to one of Claims 1 to 3, characterized in that the gear pump (20) permits a maximum delivery pressure of about 100 bar, and the low-pressure-limiting valve (40) and if need be the low-pressure-limiting safety valve (44) are set to about 70 bar.
5. Hydraulically operated ratchet driver with a double-acting hydraulic cylinder/piston drive according to one of Claims 1 to 4, characterized in that the radial piston pump (20) permits a maximum delivery pressure of about 700 bar, and the high-pressure-limiting safety valve (43) can be set within a control range between the low pressure and about 700 bar.
6. Hydraulically operated ratchet driver with a double-acting hydraulic cylinder/piston drive according to one of Claims 1 to 5, characterized in that the maximum working-stroke-chamber volume, on account of the piston rod (15), is larger than the maximum return-stroke-chamber volume, and the ratio is designed to be about 3:1.
7. Hydraulically operated ratchet driver with a double-acting hydraulic cylinder/piston drive according to one of Claims 1 to 6, characterized in that the pump-motor control (22) can be activated manually or automatically, and the driving operation can be controlled manually and/or as a function of time and/or as a function of working pressure and/or as a function of torque.
8. Hydraulically operated ratchet driver with a double-acting hydraulic cylinder/piston drive according to one of Claims 1 to 7, characterized in that the pump motor (4) is an electric motor or an air motor or a hydraulic motor.

Images