Steplessly adjustable hydraulic insert valve

A steplessly adjustable hydraulic insert valve has a housing defining a radial direction and an end side in an installation direction. An inflow connector on the end side is connectable to a pressure medium source. First and second working connectors and a return connector are arranged in the radial direction. The return connector is connectable to a pressure medium tank. The housing has an axial bore and an actuator guided movably therein. The actuator can be held in an axial center position by at least one spring and is adjustable steplessly axially out of the center position by controllable actuation. At least one of the working connectors is fluidically connectable to the return connector by axial adjustment of the actuator. The actuator has a radial widened portion with first and second control edges for steplessly opening and/or closing first and second radial openings, respectively, of the return connector.

This application claims priority under 35 U.S.C. §119 to patent application no. DE 10 2012 222 399.1, filed on Dec. 6, 2012 in Germany, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

The disclosure relates to a steplessly adjustable hydraulic insert valve in accordance with the description below.

It is known that proportional directional valves which permit a stepless change in a hydraulic volumetric flow are used in numerous hydraulic applications. For example, proportional directional valves of this type can be used in hydraulic control plate valves for tractors and mobile work implements. One example of a valve of this type is apparent from DE 10 2008 013 270 A1 in the form of a 4/3-way insert valve which makes four hydraulic connectors and three valve positions possible. The electromagnetically actuable directional insert valve which is described therein is provided for being installed into a receiving bore or a stepped bore. It is disadvantageous that a proportional directional valve of this type is structurally complicated and therefore has to be manufactured expensively.

A proportional valve is apparent from EP 1 420 321 A2 which has a completely different connector configuration from the above-described directional insert valve which is known from DE 10 2008 013 A1. It has a housing with a first and a second working connector, an inflow connector and a return connector. A valve slide is received axially displaceably in the housing and is held in an axial center position by at least one spring. The valve slide can be adjusted out of the center position in two opposed axial directions by means of a magnet. Away from the center position, furthermore, in each case one working connector is connected fluidically to the return connector, the other working connector being pressure-controlled. It is disadvantageous that a proportional valve of this type is structurally complicated and therefore of expensive configuration. It has proven disadvantageous in practice that a valve of this type requires a relatively large amount of installation space.

A further example of a proportional valve is described in U.S. Pat. No. 5,249,603 A. It is also disadvantageous here that the described valve is of structurally complicated construction and requires a relatively large amount of installation space.

It is therefore the object of the disclosure to provide a space-saving insert valve using means which are structurally as simple as possible, with the option of hydraulic pressure control.

This object is achieved by way of a hydraulic insert valve having the features described below.

Advantageous developments of the disclosure are specified in the description below.

SUMMARY

The steplessly adjustable hydraulic insert valve according to the disclosure has a housing which, on the end side in its installation direction, has a hydraulic inflow connector which can be connected to a pressure medium source and, in the radial direction, has a first and a second hydraulic working connector which can be connected fluidically, in particular, to a hydraulic actuator or consumer, and has a hydraulic return connector which can be connected to a pressure medium tank. The housing has an axial bore with an actuator which is guided axially movably therein, can be held in an axial center position by means of at least one spring and can be adjusted steplessly axially out of the center position by way of a controllable actuation. The first working connector and/or the second working connector can be connected fluidically to the return connector by way of an axial adjustment of the actuator. According to the disclosure, the actuator has a radial widened portion with a first control edge for steplessly opening and/or closing a first radial opening of the return connector and with a second control edge for steplessly opening and/or closing a second radial opening of the return connector.

Stepless adjustability of the actuator is to be understood to mean that the first and the second control edge can continuously open and close the associated radial openings of the return connector when the actuator is moved out of its spring-centered center position in the corresponding axial direction. Here, the actuator can be a valve slide which is known in hydraulics and has a radial widened portion. In order to form the first and/or the second radial opening of the return connector, the housing of the insert valve can have, for example, a first row of radial apertures and a second row of radial apertures. The actuator can be mounted in such a way that it can be moved within the axial bore out of a spring-centered center position in two opposed axial directions by way of actuation, the actuation preferably taking place electromagnetically. The pressure medium source can be any desired type of device which generates hydraulic pressure, for example a hydraulic pump.

The structural embodiment according to the disclosure of the actuator permits a particularly short overall configuration of the insert valve. As a result, it is advantageously possible to insert or install said insert valve into a receiving bore for a 4/3-way proportional valve in a cartridge configuration with identical connector configuration. In other words, the disclosure provides a 4/3-way pressure control valve which, with an identical connector configuration, fits into the receiving bore of a 4/3-way proportional valve. It is notable here that the insert valve according to the disclosure is of considerably simpler construction than a corresponding proportional valve. The disclosure therefore makes the ability to exchange a conventional proportional valve possible in a particularly inexpensive way.

The fluidic connection of the first and/or second working connector to the return connector can be controlled particularly precisely if the widened portion of the actuator is delimited axially by a first axial face and a second axial face which points away from said first axial face, it being possible for in each case one of the axial faces to be relieved fluidically away from the axial center position of the actuator. An advantage of this is that in each case one of the two axial faces is relieved toward the return connector away from the center position of the actuator, with the result that only the fluidic force on the other, that is to say the active, axial face is utilized for pressure regulation of the insert valve. Moreover, a radial widened portion, configured in this way, of the actuator can be manufactured simply in terms of manufacturing technology.

One particularly advantageous embodiment of the disclosure provides that, in the center position of the actuator, the first axial face is arranged in the region of the first radial opening of the return connector and the second axial face is arranged in the region of the second radial opening of the return connector. This spatial arrangement of the widened portion along the actuator permits a particularly simple embodiment of the insert valve.

It is expedient if the first and/or the second working connector in each case have/has a first and a second radial opening which are spaced apart from one another in the axial direction. Here, the first and the second radial opening can penetrate the housing in the radial direction, for example in the form of a first row of apertures and a second row of apertures.

One advantageous embodiment of the disclosure provides that the first radial opening of the first and/or the second working connector is connected fluidic ally to in each case one axial face of the actuator.

It is advantageous if a fluidic connection of the inflow connector to the respective working connector can be controlled steplessly by means of the second radial opening of the first and/or the second working connector.

In one preferred development of the disclosure, the actuator has an axial bore which runs in the longitudinal direction of the actuator or the insert valve and can be connected fluidically to the inflow connector of the insert valve. An axial bore can be introduced simply in terms of manufacturing technology into the actuator and makes precise control of a fluid flow from the inflow connector through the actuator possible. Furthermore, the axial bore of the actuator makes it possible to save an annular sealing element in the form of what is known as an O-ring.

One advantageous embodiment of the disclosure provides that the axial bore of the actuator has a first radial opening and a second radial opening which can be connected fluidically to the first and/or the second working connector.

For precise guidance of the actuator and simple mounting capability of the actuator within the housing, it has proven advantageous if a separate first bush and a separate second bush can be introduced into the housing and can be fastened in the housing. The first and the second bush therefore make simple mounting possible of the actuator including its widened portion within the axial bore of the housing, which axial bore can therefore have a constant bore diameter throughout. In addition, the actuator is mounted in an axially displaceable manner, without permitting tilting of the actuator within the axial bore of the housing.

In order to seal the axial bore of the housing in the axial direction and at the same time to make a fluidic connection of the valve connectors possible, the first bush and/or the second bush can in each case have a radial opening which can be connected fluidically to in each case one working connector.

The disclosure can be utilized particularly advantageously if the insert valve is configured as what is known as a cartridge valve.

DETAILED DESCRIPTION

The FIGURE shows an insert valve1according to the disclosure of cartridge configuration in a longitudinal section. An insert valve1of this type is particularly suitable for installation in a receiving bore, into which otherwise a conventional 4/3-way valve is installed, as is known, for example, from DE 10 2008 013 270 A1. That is to say, the 4/3-way valve which is known from DE 10 2008 013 270 A1 can be replaced by the insert valve1according to the disclosure, without it being necessary for the receiving bore to be modified appreciably for this purpose.

The insert valve1has a housing2which is preferably manufactured from a steel. On an end side which is arranged on the left in the FIGURE, the housing2has a hydraulic inflow connector4, via which a pressure medium, that is to say, for example, a hydraulic oil, can be fed to the insert valve2in a feed direction P, that is to say in a pressure feed direction. The inflow connector4is formed by a closure piece6which is screwed into the housing2and has an inlet bore8provided in it. The closure piece6is manufactured from a steel and is covered by an inflow screen10which is manufactured from plastic, in order to be protected against the ingress of dirt. For screwing into the housing2, the closure piece6has an external thread which interacts with an internal thread of the housing2.

An annular sealing element12in the form of an O-ring is arranged on the outer side of the housing2downstream of the inflow connector4in the inflow direction P, which annular sealing element12is received in the circumferential groove14of the housing2. The annular sealing element12seals the inflow connector4with respect to the receiving bore when the insert valve1is installed in a receiving bore.

Furthermore, the housing2has a first hydraulic working connector16which is arranged downstream of the annular sealing element12in the feed direction P. The first working connector16is configured in the form of a groove which is circumferential on the outside of the housing2, and has a first row of radial openings18and a second row of radial openings20which are spaced apart from one another in the axial direction of the insert valve1, that is to say in the feed direction P. In other words, the first working connector16has two radial openings18,20which are separated fluidically from one another and penetrate the housing2in the radial direction. That is to say, the first and the second row of radial openings18,20represent two individual ducts, which are separated from one another, of the first working connector16. The first and the second row of radial openings18,20can be introduced into the housing2in the form of bores.

A further annular sealing element22is arranged in a circumferential groove24of the housing2downstream of the first working connector16in the inflow direction P. Said annular sealing element22seals the first working connector16from a return connector26which is arranged downstream of it in the inflow direction P, when the insert valve1is installed in the receiving bore. The return connector26is configured in the form of a groove which is circumferential on the housing2, and has a first row of radial openings28and a second row, separate fluidically from the former, of radial openings30which are spaced apart from one another in the inflow direction P. That is to say, the first and the second row of radial openings28,30represent two individual ducts, which are separated from one another, of the return connector26. A pressure medium which is fed to the insert valve1can be fed via the return connector26, for example, to an oil tank (not shown).

Furthermore, the housing2has a further annular sealing element32in the form of an O-ring which is received in a circumferential groove34of the housing2and seals the return connector26fluidically with respect to a second working connector36which is arranged downstream of it in the feed direction P. The second working connector36is configured in the form of a circumferential groove37on the outside of the housing2and has a first row of radial openings38and a second row of radial openings40. The first and the second row of radial openings38,40of the second working connector36are spaced apart from one another in the inflow direction P and are separated from one another fluidically. That is to say, the first and the second row of radial openings38,40represent two individual ducts, which are separated from one another, of the second working connector36. They can be introduced into the housing2, for example, in the form of bores. A further annular sealing element42is arranged downstream of the second working connector36in the inflow direction P, which further annular sealing element42seals the second working connector36with respect to the receiving bore, when the insert valve1is installed into the latter. Furthermore, a housing seal43which seals the housing2is provided.

On an end side of the housing2which lies opposite the inflow connector4, a coil housing44which is manufactured from a steel sheet is flange-connected to said housing2. A first and a second magnet coil46,48which are supported by a coil former50which is manufactured from plastic are arranged in the coil housing44. In this exemplary embodiment, the coil former50is manufactured from polyamide. The two magnet coils46,48can be actuated by means of an electric line52. The coil former50is arranged adjacently with respect to a pole tube54which is manufactured from a steel. The pole tube54has a magnetic separation in the form of two non-magnetic insert rings56which can also, as an alternative, be configured as a non-magnetic welded seam. A non-magnetic sleeve58and a magnet armature60which is manufactured from a soft iron are arranged within the pole tube54. The magnet armature60has a longitudinal bore62for the passage of a pressure medium, which longitudinal bore62makes a movement of the magnet in the axial direction possible. An end closure piece64, manufactured from a steel, of the pole tube54including an end stop65which is manufactured from brass for the magnet is arranged at an outer end of the coil housing44.

Furthermore, the housing2has an axial bore66which extends along the longitudinal direction of the insert valve1, that is to say in the feed direction P. An actuator68which is guided in an axially movable manner and is configured in the form of a valve slide is received in the axial bore66. The actuator68is held in a spring-centered manner in the center position by a first spring70which is supported on the closure piece6in the housing2and a second spring71which is supported on the end closure piece64in the coil housing44. The second spring71transmits its force to the actuator68by means of a driving connection72.

The actuator68has an external diameter which is smaller than the internal diameter of the axial bore66. In a central region, the actuator68has a radially directed, that is to say protruding in a radial direction, widened portion74which is fitted into the axial bore66. The widened portion74defines a first axial face76and a second axial face78which is directed in the opposite direction to the former. In other words, the two axial faces76,78point away from one another. The widened portion74and therefore the first and the second axial faces76,78are arranged on the actuator68in such a way that they are situated in the region of the return connector26in the spring-centered center position of the actuator68. In particular, the first axial face76is arranged in the region of the first radial opening28and the second axial face78is arranged in the region of the second radial opening30of the return connector26when the actuator68is situated in its center position. In this way, the axial faces76,78form in each case one control edge80,82which can steplessly close and steplessly open in each case one of the rows of radial openings28,30of the return connector26when the actuator68is moved or is adjusted magnetically in a corresponding axial direction.

Furthermore, the actuator68has an axial bore84which extends from the inflow connector4in the direction of the coil housing44as far as the second working connector36. The axial bore84of the actuator68is connected fluidically to the inflow connector4. In the region of the first working connector16and the second working connector36, in each case one row of radial openings86,88are provided on the actuator68, of which in each case one row can be connected fluidically to the first and the second working connector16,36, respectively. In each case one circumferential groove90,92is provided in the region of the rows of radial openings86,88.

The mounting of the actuator68within the axial bore66takes place via a first and a second bush94,96, which are inserted in each case as components which are separated from the housing2, that is to say components which are in each case separate, into the axial bore66of the housing2and are fastened therein. The first and second bush94,96make the mounting of the actuator68possible, which actuator68would otherwise only be capable of being inserted with difficulty on account of its widened portion74. As can be seen clearly in the FIGURE, the bushes94,96therefore fulfill two tasks, namely the mounting of the actuator68and a spatial delimitation of pressure spaces between the axial bore66and the actuator68.

Each of the bushes94,96has a row of radial openings98,100which can be configured, for example, as continuous bores. Together with the rows of radial openings86,88of the actuator68, the rows of radial openings98,100form in each case one control edge for controlling a fluidic connection from the inflow connector4to the first and to the second working connector16,36, respectively. Furthermore, the bushes94,96in each case have a groove102,104which is circumferential on the outside, which grooves102,104are arranged in the region of the first row of radial openings18of the first working connector16and the first row of radial opening38of the second working connector36, respectively.

A steplessly adjustable hydraulic insert valve is disclosed having a housing which, on the end side in its installation direction, has an inflow connector which can be connected to a pressure medium source and, in the radial direction, has a first and a second working connector and a return connector which can be connected to a pressure medium tank. The housing has an axial bore with an actuator which is guided axially movably therein, can be held in an axial center position by means of at least one spring and can be adjusted steplessly axially out of the center position by way of a controllable actuation. The first working connector and/or the second working connector can be connected fluidically to the return connector by way of an axial adjustment of the actuator. According to the disclosure, the actuator has a radial widened portion with a first control edge for steplessly opening and/or closing a first radial opening of the return connector and with a second control edge for steplessly opening and/or closing a second radial opening of the return connector.

LIST OF REFERENCE NUMERALS

1Insert valve2Housing4Inflow connector6Closure piece8Inlet bore10Inflow screen12Annular sealing element14Circumferential groove16First working connector18First row of radial openings of the first working connector20Second row of radial openings of the first working connector22Annular sealing element24Circumferential groove26Return connector28First row of radial openings of the return connector30Second row of radial openings of the return connector32Annular sealing element34Circumferential groove36Second working connector37Circumferential groove38First row of radial openings of the second working connector40Second row of radial openings of the second working connector42Annular sealing element43Housing seal44Coil housing46First magnet coil48Second magnet coil50Coil former52Electric line54Pole tube56Insert ring58Non-magnetic sleeve60Magnet armature62Longitudinal bore64End closure piece65End stop66Axial bore68Actuator70First spring71Second spring72Driving connection74Radially directed widened portion76First axial face78Second axial face80Control edge82Control edge84Axial bore of the actuator6886First row of radial openings of the actuator6888Second row of radial openings of the actuator6890Circumferential groove92Circumferential groove94First bush96Second bush98Row of radial openings of the first bush94100Row of radial openings of the first bush96102Circumferential groove104Circumferential grooveA Flow direction of a hydraulic pressure mediumB Flow direction of a hydraulic pressure mediumP Feed direction of a hydraulic pressure mediumT Flow direction of a hydraulic pressure medium