EP1251277A2 - Pressure averaging power control system - Google Patents

Abstract

The device has a stepped piston (6) with two input step surfaces (12a,b), and an output pressure surface (26). To generate a reduced output pressure, the output pressure surface is larger than the sum of the input step surfaces. The stepped piston consists of a first and a second section, and an axial transverse load is transmitted from the first to the second section. The input step surfaces are located on the first piston section, the output pressure surface is located on the second piston section.

Description

The invention relates to a diaphragm seal and a Power control device in particular for controlling the Total output of several hydrostatic piston machines.

Diaphragm seals that averaged from two inlet pressures Generate output pressure are z. B. from DE 34 07 827 C2 known. They have a stepped piston, which in one Housing is axially displaceable. The stepped piston has two step surfaces oriented in the same direction, the can be acted upon by an inlet pressure in each case and whose radially outer boundary with the housing of the Diaphragm seal is designed as a variable throttle. In the Supply from the throttling points to a common one A check valve is arranged in each case in the outlet line. A surface opposite to the step surfaces, which is equal to the sum of the two step areas with the pressure taken from the outlet line acted upon. Through the on the step surfaces through the Forces acting in the input pressures or in opposite direction by the outlet pressure acting The stepped piston moves into a force Equilibrium position. The equilibrium of the Step piston is reached when the outlet pressure is the same is the arithmetic mean of the input pressures.

The function of the known diaphragm seal is limited to a pure averaging of two inlet pressures to one Outlet pressure equal to the arithmetic mean of Is the input pressure. The diaphragm seal shows none Intervention on so that for more Functionalities additional components are required. This increases the construction effort e.g. by connecting different assemblies with pressure lines considerably. In addition, the development effort increases Matching different assemblies to each other. Especially the cumulative losses are disadvantageous in operation of the individual assemblies.

For power control of several hydrostatic Piston engines are known, one for each piston engine to provide their own power controller. The regulation takes place doing that on each power control device arranged step piston. One step surface each acted upon by the working pressure of a piston machine, so that a stepped piston is arranged in each piston machine is the number of stages of the number to be regulated Corresponds to piston machines and that with every piston machine connected is.

The supply of the working pressure of a piston machine to the Power control device of the other piston machine requires a high one for just two piston machines Line effort. The effort for the components also increases there is a separate control device for each piston machine is required.

It is the object of the invention Power control device for controlling the total power several hydrostatic working machines and one To create diaphragm seals, in which a reduction in Output pressure is integrated, so that for the Power control device a common control variable is available.

The object is achieved by the diaphragm seal according to the invention with the characterizing feature of claim 1 and by the power control device according to the invention with the characteristic feature according to claim 7 solved. The Subclaims relate to advantageous developments of the Invention.

Embodiments of the diaphragm seal according to the invention and the power control device are in the drawings shown and explained in the following description.

Fig. 1

eine schematische Darstellung eines ersten Ausführungsbeispiels eines erfindungsgemäßen Druckmittlers;

Fig. 2

eine schematische Darstellung eines zweiten Ausführungsbeispiels eines erfindungsgemäßen Druckmittlers

Fig. 3

eine schematische Darstellung einer erfindungsgemäßen Leistungsregelvorrichtung mit einer hydraulischen Übersteuerung; und

Fig. 4

eine schematische Darstellung einer erfindungsgemäßen Leistungsregelvorrichtung mit einer elektromagnetischen Übersteuerung.

Show it:

Fig. 1

a schematic representation of a first embodiment of a diaphragm seal according to the invention;

Fig. 2

a schematic representation of a second embodiment of a diaphragm seal according to the invention

Fig. 3

a schematic representation of a power control device according to the invention with a hydraulic override; and

Fig. 4

is a schematic representation of a power control device according to the invention with an electromagnetic override.

In Fig. 1 is a partial section through an inventive Diaphragm seal 1 shown. The diaphragm seal 1 consists of a housing 2, in which a blind hole 3 is made. The blind bore 3 serves to receive a valve sleeve 4. The valve sleeve 4 has one over its entire length extending stepped through hole 5. Take it the diameter of the stepped through hole 5 from the bottom the blind bore 3 in the direction of the open end. In the Through hole 5, a stepped piston 6 is used, whose length extension is smaller than that Linear expansion of the valve sleeve 4. The stepped piston 6 is slidable in the through bore 5 in the axial direction. To fix the valve sleeve 4 in the blind bore is a Neck 7, for example, in an expanded part of the Blind hole 3 screwed so that an inserted disc 8 with a central through hole, the valve sleeve 4 on Bottom of the blind hole 3 holds.

In order to supply inlet pressures, 2 Input pressure bores 9a, 9b are provided, which in circumferential grooves 10a, 10b open out on the outside in the Valve sleeve 4 are introduced. Create the grooves 10a, 10b with the inner wall of the blind hole 3 a circumferential channel, that via the inlet pressure bores 9a, 9b with pressure medium is to be supplied. The circumferential grooves 10a, 10b are through Radial bores 11a, 11b with that stepped through Through hole 5 formed interior of the valve sleeve 4 connected.

The stepped piston 6 has three sections with Diameters D1, D2 and D3, each with one Diameter of the stepped through hole 5 correspond and cooperate in a sealing manner. Between Sections with the diameters D3 and D2 and between the sections with the diameters D2 and D1 is a with Reduced cross-section of part of the stepped piston 6 arranged. This creates between the part of the Step piston 6 with a reduced cross section and Inner wall of the valve sleeve 4 each have an annular space 13a, 13b. The expansion of the annular spaces 13a, 13b in the axial direction is dimensioned so that between the radial bores 11a, 11b and an output bore 14a, 14b each flow-through connection can be established if the Step piston 6 is in a first end position. On The annular spaces are on the sides of the output bores 14a, 14b 13a, 13b delimited by entrance step surfaces 12a, 12b. The outer peripheral edges of the input step surfaces 12a, 12b close off when the stepped piston 6 moves its first end position at the same time increasingly Output bores 14a, 14b. It will be variable together Throttle point trained. The on the stepped piston 6 trained input step surfaces 12a, 12b are each larger than that on the opposite side Areas 13a, 13b delimiting surfaces of the stepped piston 6. Due to the prevailing in the annular spaces 13a, 13b The input piston experiences a force which is in Direction of the bottom of the blind hole 3 is directed.

The output bores 14a, 14b, of which preferably several distributed over the circumference of the valve sleeve 4 are arranged, each open into an annular channel 15a, 15b. The ring channels 15a, 15b are each with a bore a check valve 16a, 16b connected. The Check valves 16a, 16b have an identical structure on, and consist of a pressed into the housing 2 Valve seat body 17, the one with a valve tappet 18 Sealing seat interacts. The valve lifter 18 is axially from a valve spring 19 with a force in the direction of Valve seat body 17 acted upon. The valve spring 19 supports in a valve holder 20, which in the housing 2 screwed in and sealed by an O-ring.

The valve lifters 18 of the check valves 16a, 16b penetrate an output line 21 which in the area of Valve tappet 18 is expanded so that the pressure medium Can flow around valve stem 18. That of the annular spaces 13a, 13b via the throttle bores 14a, 14b and Check valves 16a, 16b into the outlet line 21 flowing pressure medium can via an outlet bore 22 be used for further use. The output line 21 is also via a throttle 23 with the Tank line system 24 connected. An outlet pressure chamber 25, which is formed in the through bore 5 of the valve sleeve 4 is over another radial bore and one circumferential groove connected to the output line 21. The in The outlet line 21 pressure acts on an output pressure surface 26 and the end face of a Stop 27, which is arranged on the stepped piston 6. As The outlet pressure thus creates a pressure that is opposite the arithmetic mean of the input pressures in relation the sum of the input step areas 12a, 12b to the Output pressure area 26 is reduced.

To the closing pressure of the check valves 16a, 16b to the to adapt to changed pressure conditions, they are as adjustable check valves 16a, 16b. The For example, setting can change the The valve spring 19 is pretensioned. This will ensures that when increasing an inlet pressure the check valve 16a associated with the other inlet pressure or 16b closes, albeit between the lower he two inlet pressures and the outlet pressure at the assigned check valve 16a or 16b a positive There is a pressure difference.

To connect an override line, not shown introduced into the connecting piece 7, a connection hole 9, the one Has internal thread. By not shown Override line can face 30 of the stepped piston 6 can be pressurized to the Step piston 6 causes a force in the direction of Bottom of the blind hole 3 is directed. So that can Throttle bores 14a, 14b are opened until the Stop 27 abuts the bottom of the blind hole 3.

2 is a second embodiment of a Diaphragm seal 1 according to the invention shown. Instead of in the first embodiment one-piece stepped piston 6, which is inserted into a one-piece valve sleeve 4 the second embodiment, a two-part valve sleeve consisting of a first valve sleeve part 33 and a second valve sleeve part 34. The second Valve sleeve part 34 has one in the axial direction continuous, stepped guide recess 36, the smaller radial extension of the guide recess 36 to The bottom of the blind hole 3 is oriented. In the The guide recess 36 is the second stepped piston part 32 used. The second stepped piston part 32 also has one level, with the radial Extents with the radial extents of the Guide recess 36 correspond and seal interact. The steps in the second step piston part and the guide recess 36 are in the axial direction staggered. The trained one Outlet pressure chamber 25 is via a radial bore and Circumferential groove on the second valve sleeve part 34, as in the first exemplary embodiment, with the output line 21 connected.

From the bottom of the blind hole 3 is in the second Stepped piston part 32 introduced a compensating bore 37, which is designed as a blind hole. On its outer geometry the second stepped piston part 32 points toward the first Step piston part 31 oriented side a circumferential Paragraph 39 on, through an overflow bore 38 with the Compensating bore 37 is connected. The resulting one circumferential channel is with the tank line system 24 for example, on the front in the second Valve sleeve part 34 inserted grooves connected. On between the bottom of the blind hole 3 and the second Step piston part 32 resulting from movement over or Vacuum can thus be generated by the tank line system 24 be dismantled.

On the first step piston part 31 facing The end face of the second stepped piston part 32 is one dome-shaped contact surface 40 is formed. The Contact surface 40 is in contact with the end face of the first step piston part 31. This allows the two Stepped piston parts 31 and 32 thrust forces in the axial direction transfer. In the first insert body part 33 is the Durchgangsborhung 5 introduced with the graded first stage piston part 31 cooperates, as in the Description of the first embodiment explained. By the division of the insert body part 4 and the step piston 6 in a first and second insert body part 33 and 34 and first and second step piston parts 31 and 32 there is the possibility of the effective area for the Limit the outlet pressure to the outlet pressure surface 26, since the guide recess 36 to the bottom of the blind hole 3 radial expansion can be reduced again and cooperates sealingly with the stop 27, so that the End face of the stop 27 no effective area represents. Furthermore, tolerances lead to manufacturing can occur, not to tension the step piston 6 in the through hole 5.

As stated in the first embodiment, the Step piston 6 is subjected to an oversteering force become. 2 is the first Stepped piston part 31 with its towards the open end of the housing 2 oriented end face by an electromagnet 41 acted upon by an oversteering force. The electromagnet 41 is in the connection bore 29 of the nozzle 7th screwed, from the housing of the electromagnet 41st a plunger 42 protrudes on the end face, preferably with is provided with a thread so that an adjusting sleeve 43 can be positioned axially. The illustrated Versions of the diaphragm seal 1 with a one-piece or multi-part stepped piston 6 can be in any way combine with the oversteering options shown.

In Fig. 3 is a power control device for control the total output of two adjustable hydrostatic Piston machines shown schematically. A first and second piston machine 50, 51 are replaced by a first or second drive shaft 52, 53 driven. The one in her Delivery volume adjustable first or second piston machine 50, 51 convey a pressure medium into a first or second Working line 54, 55. The to build a required power control device according to the invention identical components for the first and second Piston engine 50, 51 are intended based on their interaction be explained with the first piston machine 50. there only the components on the first piston machine 50 explained, the reference numerals are provided with a. The Components on the second piston machine 51 are identical and the reference symbols are provided with b.

For adjusting the delivery volume of the first piston machine 50, an adjustment device 56a is provided. The Adjustment device 56a has an actuating piston 60a, which on two oppositely arranged piston surfaces with one in a signal pressure space 58a or in one Operating pressure chamber 59a prevailing pressure is applied. The effective piston area is in the signal pressure space 58a larger than the effective piston area in the Operating pressure space 59a. The operating pressure chamber 59a is over a line system with the first working line 54 connected. The signal pressure chamber 58a is connected via a line a port of a control valve 57a connected in a first end position, the working pressure line 54a with the Signal pressure chamber 58 connects.

The resulting pressure balance in the Operating pressure chamber 59a and the control pressure chamber 58a generated due to the larger acting piston area in the Control pressure chamber 58a a force that the control piston 60a and so that the first piston machine 50 in the direction of a reduced funding volume adjusted. The movement of the Actuating piston 60a is connected via a connecting device 61a transferred to the control valve 57a. The control valve 57a is via the connecting device 61a in the direction of it force applied to the second end position. In the The second end position of the control valve 57a is Connecting line of the signal pressure chamber 58a with the Tank line system 24a connected. The control valve 57a is biased by an adjusting spring 69a.

In the opposite direction, the control valve 57a is turned on a hydraulic control member 62a with a force applied. The hydraulic control member 62a consists of a control piston 63a which is pressurized on both sides is acted upon. The control piston 63a is one adjustable spring in a spring chamber 64a with a Force biased by the spring in the spring chamber 64a the force of the adjusting spring 69a is compensated for and Control valve 57a is in a defined starting position located. The spring chamber 64a is connected to the outlet line 21 of the diaphragm seal 1 connected. In the first illustrated The embodiment is the diaphragm seal 1 hydraulic can be overridden and with an override pressure line 65 connected. The inlet pressure bores 9a, 9b of the Diaphragm seals 1 are connected via a first inlet pressure line 66 and a second inlet pressure line 67 with the first Working line 54 or the second working line 55 connected.

The control piston 63a is in the spring chamber 64a with the in the outlet line 21 prevailing outlet pressure pressures proportional to the mean pressure of the first and second working lines 64, 55. Increases in the first and / or second working line 54, 55 the pressure, this also leads to an increase in pressure in the Output line 21. The in the spring chamber 64a on the Control piston 62a acting increased pressure generates a force the control valve 57a in the direction of the first end position, so that the pressure in the control pressure chamber 58a the pressure in the first working line 54 is approximated. According to the This results in a description above Adjustment of the first piston machine 50 to less Delivery volume. The adjustment described above for smaller funding volumes takes place in an analogous manner at second piston machine 51. By reducing the Delivery volume of the two piston machines 50, 51 at one Rise in pressure in one of the working lines 54, 55 the total power remains constant. In an analogous way a pressure drop in one of the working lines 54, 55 to one Adjustment of the piston machines 50, 51 in the direction of a larger funding volume.

If the pressure in one of the working lines exceeds 54 or 55 a critical pressure, so can over the Override pressure line 65 of diaphragm seal 1 overridden be so that by the displacement of the stepped piston 6th the throttles on the input step surfaces 12a, 12b are opened become and the pressure in the outlet line 21 increases. The Piston engines 50, 51 are in the minimum direction Funding volume adjusted. Contrary to that on the control piston 63a acting force generated in the spring chamber 64a the piston through a second control pressure line 68a a second control pressure can be applied. This is the starting position for the power control device adjustable.

In contrast to that shown in Fig. 3 Embodiment of a power control device with hydraulic override device in Fig. 4 is a Power control device shown a Diaphragm seal with an electromagnetic Override device 70 has.

Claims (8)

Diaphragm seal for providing an outlet pressure averaged from at least two inlet pressures, with a step piston (6) which is displaceably arranged in a housing (2) and which has at least two inlet step surfaces (12a, 12b) oriented in the same direction, each of which can be acted upon by one of the inlet pressures and the outside thereof Scopes are designed as control edges of jointly variable throttles, and with at least two check valves (16a, 16b), which are each arranged in a connecting line from the variable throttle to an output line (21), and one on the stepped piston (6), in opposite directions outlet pressure surface (26) which is oriented towards the inlet step surfaces (12a, 12b) and can be acted upon by the outlet pressure
characterized in that, in order to generate a reduced outlet pressure, the outlet pressure area (26) is larger than the sum of the inlet step areas (12a, 12b). Diaphragm seal according to claim 1,
characterized in that the step piston (6) consists of a first step piston part (31) and a second step piston part (32) and axial thrust forces can be transmitted from one step piston part (31; 32) to the other step piston part (32; 31). Diaphragm seal according to claim 2,
characterized in that the input step surfaces (12a, 12b) are arranged on the first step piston part (31) and the output pressure surface (26) is arranged on the second step piston part (32). Diaphragm seal according to one of claims 1 to 3,
characterized in that an oversteering force acting in the same direction as the force generated on the input step surfaces (12a, 12b) can be generated on an end surface (30) arranged opposite the output pressure surface (26). Diaphragm seal according to claim 4,
characterized in that the oversteering force on the step piston (6) can be generated hydraulically by a pressure on the end face (30). Diaphragm seal according to claim 4,
characterized in that the oversteering force on the step piston (6) can be transmitted to the end face (30) by a plunger (42, 43) of an electromagnet (41). Power control device for controlling the total power of at least two hydrostatic piston machines (50, 51), the delivery volume of which can be adjusted by means of a hydraulic adjusting device (56a, 56b) via a control pressure, the control pressure for the adjustment devices (56a, 56b) using a control valve ( 57a, 57b) can be regulated,
characterized in that a hydraulic control element (62a, 62b) is provided for controlling the control valves (57a, 57b), the common control pressure of which can be generated by a common pressure transmitter (1), the control pressure being derived from the operating pressures of the piston machines (50, 51) is the mean and reduced outlet pressure. Power control device according to claim 7,
characterized in that a control piston (63a, 63b) of each hydraulic control member (62a, 62b) can be acted upon with a second control pressure, the force of which is opposite to the control pressure.

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