WO2016034402A1

WO2016034402A1 - Proportional valve that can be actuated electromagnetically

Info

Publication number: WO2016034402A1
Application number: PCT/EP2015/068933
Authority: WO
Inventors: Michael IMHOF; Tobias Landenberger
Original assignee: Robert Bosch Gmbh
Priority date: 2014-09-01
Filing date: 2015-08-18
Publication date: 2016-03-10
Also published as: DE102014217441A1

Abstract

The invention relates to a proportional valve that can be actuated electromagnetically to control the flow of a working medium, comprising a valve body (1) with a bore (2), in which at least sections of a valve member (3) are accommodated, said valve member having a sealing surface (5) that interacts with a valve seat (4) and being axially adjustable to connect an inlet (6) to an outlet (7). According to the invention, the valve member (3) is axially prestressed against the valve seat (4) via the spring force of a spring (8).

Description

Description title

Electromagnetically actuated proportional valve

The invention relates to an electromagnetically verifiable proportional valve for controlling the flow of a working medium having the features of the preamble of claim 1. The working medium may be both a liquid and a gas.

State of the art

From the published patent application DE 199 43 066 AI an electromagnetically operable, hydraulic proportional valve is known which comprises a magnetic part and a valve member. The magnet part has an electrically controllable coil, a stationary core projecting into the interior of the coil and a displaceably guided armature, which is acted on by the coil, for coupling to an axially adjustable closing element. The coupling is preferably via a plunger. The axially adjustable closing member is at least partially conical and forms together with a valve seat a conical seat valve. The valve seat is formed by an inserted into a bore of the valve member pinhole.

The present invention has for its object to provide an electromagnetically actuated proportional valve, which meets very high requirements in terms of its tightness. Furthermore, a high positioning accuracy with regard to the flow rate to be achieved.

To solve the problem, the electromagnetically actuated proportional valve with the features of claim 1 is proposed. Advantageous developments of the invention can be found in the dependent claims. Disclosure of the invention

The proposed for controlling the flow of a working medium electromagnetically actuated proportional valve comprises a valve body having a bore in which at least partially a valve member is received, which has a cooperating with a valve seat sealing surface. To connect an inlet with a drain, the valve member is axially adjustable. According to the invention, the valve member is axially biased against the valve seat via the spring force of a spring. The spring force of the spring causes a sealing force which increases the tightness of the proportional valve. The sealing force can be further increased if applied to a surface facing away from the sealing surface of the valve member, a hydraulic or pneumatic pressure, which exerts a closing force on the valve member. In this case, the respective forces add up.

Preferably, the spring for axially biasing the valve member against the valve seat in the bore of the valve body is arranged, in which the valve member is at least partially accommodated. One end of the spring can thus be supported directly on the valve member. Preferably, the support via an end face of the valve member, which faces away from the sealing surface. Further preferably, the spring via a securing element, for example in the form of a ring inserted into the bore, on which the valve member remote from the end of the spring is supported axially fixed in position. Advantageously, the securing element is pressed into the bore. Because this type of connection with the valve body simplifies the production of the fuse element, since, for example, the formation of a thread can be omitted. At the same time, the axial preload force of the spring acting on the valve member can be adjusted via the press-in depth of the securing element.

Further preferably, the spring is arranged in a serving as an inlet portion of the bore of the valve body. On the end face of the valve member, on which preferably the spring is supported directly, thus is the inlet pressure. This causes the valve member in the closing direction in addition to the spring force is acted upon by a hydraulic or pneumatic pressure force. As a result, the tightness in the region of the valve seat is further increased. At the serving as a feed portion of the bore, a portion of the bore connects to the formation of the valve seat preferably radially and / or obliquely with respect to a longitudinal axis A. A radial course has the formation of a flat seat result, while an oblique course of the paragraph leads to the formation of a conical seat. This means that the valve seat can be designed as a flat seat or a conical seat. The cooperating with the valve seat sealing surface of the valve member may be formed accordingly, ie have a radial or oblique course with respect to the longitudinal axis A. In addition, the sealing surface may also be spherically shaped. The leading to the formation of the valve seat paragraph is further preferably oriented such that it leads to a reduction of the inner diameter of the bore in the flow direction of the working medium. The cooperating with the valve seat sealing surface of the valve member must therefore be formed upstream of the valve seat on the valve member. This means that the valve member has a sealing surface forming portion which comes to lie in the region of the inlet. This also means that the valve opens in the serving as an inlet region of the bore. The valve member is acted upon in this way by the pressure prevailing in the inlet region inlet pressure in the closing direction.

In a development of the invention, it is proposed that an elastically deformable sealing element be inserted in the valve seat and / or in the sealing surface of the valve member. The elastically deformable sealing element is able to compensate for manufacturing and / or assembly tolerances, which could lead, for example, to misalignment in the region of the valve seat and thus to leaks. In this respect, the sealing element contributes to a further improvement in the tightness of the proportional valve. Preferably, the elastically deformable sealing element made of an elastomeric material, such as rubber, in particular sponge rubber produced.

It is also proposed that the valve body has at least one serving as a drain, radially or obliquely extending bore, which opens into the valve member receiving bore, which is formed for this purpose as an axial bore. Preferably, a plurality of radially or obliquely extending holes are provided as a drain, which are arranged in a radial plane and / or at the same angular distance from each other. In order to ensure a connection of the inlet to the outlet when the valve is open, it is further preferred to have a portion of the valve member forming the sealing surface a section attached, which has a significantly reduced outer diameter relative to the inner diameter of the axial bore, so that this portion of the valve member can be flowed around by the working fluid. This may be followed by a portion having an outer diameter, which corresponds substantially to the inner diameter of the bore for guiding the valve member within the axial bore.

According to a preferred embodiment of the invention, the valve member has a substantially sleeve-shaped aperture or is connected to a substantially sleeve-shaped aperture. The diaphragm as part of the valve member is thus also axially adjustable. The aperture can therefore be used to release and close the at least one serving as a drain, radially or obliquely extending bore. This means that, depending on the axial position of the diaphragm, the at least one bore serving as a drain is either closed or at least partially released.

The diaphragm connected to the valve member leads to the formation of a slide valve, so that the proposed proportional valve preferably represents a combination of seat and slide valve. This has the advantage that in addition to a high density also a high setting accuracy of the flow is achieved.

Preferably, the substantially sleeve-shaped aperture is formed as a slit and has at least one overlapping with the drainable shell-side opening. The flow is in this case on the size, the shape and the axial position of the aperture with respect to the at least one serving as a drain, radially or obliquely extending bore specifiable. The mouth of serving as a drain hole or holes forms a control edge.

Advantageously, the at least one aperture which can be brought into overlap with the drain has a flow cross-section which enlarges or reduces in the axial direction. By this measure, flow characteristics can be represented that, for example, are not linear. The opening may in particular be designed as a slot which widens or narrows in the axial direction, so that a triangular or trapezoidal shape of the opening is formed results. In addition, the shape is arbitrary, ie it can also have at least partially an arcuate course. Such forms can be formed particularly precisely by means of laser cutting. The at least one aperture of the diaphragm has therefore preferably been produced by means of laser cutting.

In addition, it is proposed that the electromagnetic actuation of the proportional valve takes place indirectly via a plunger. About the plunger, the valve member can be acted upon with an axial force, which causes an axial displacement of the valve member. Preferably, this axial force is opposed to the spring force of the spring. That is, the electromagnetic actuator for opening the seat valve leads. If the valve member is additionally provided with a diaphragm for forming a slide valve, the flow can be adjusted via the axial position of the diaphragm with respect to at least one bore serving as a drain.

The plunger is further preferably connected to a liftable armature which cooperates with a coil of an electromagnet. The armature may for example be designed as a plunger anchor and have a central bore for at least partially receiving the plunger. If the coil is energized, armature and plunger move in the direction of the valve seat. The plunger lifts the valve member from the valve seat. The control of the flow of the working medium is effected in dependence on the applied current. This is especially true if the valve member comprises a diaphragm, by means of which at least one bore serving as a drain is controllable. Because the applied current determines the axial position of the diaphragm and thus the flow. At the same time a very high setting accuracy can be achieved via the aperture.

As already mentioned, the spring for the axial prestressing of the valve member against the valve seat is preferably supported on an end face of the valve member, which furthermore preferably is an end face facing away from the sealing face. For radial positional fixation of the spring, the end face serving for the support can be stepped. For example, the end face may have a central elevation, which engages in the spring, which is advantageously designed as a helical compression spring. A shift of the spring in the radial direction is no longer or only possible to a limited extent. This ensures that the axial preload of the Valve member used spring force, which also serves as a sealing force is transmitted as evenly as possible on the valve member.

The abovementioned measures for training and development of a proportional valve according to the invention come into play, in each case alone or in combination, in particular when the proportional valve is a normally closed valve. About the axial biasing force of the spring then the opening pressure of the proportional valve is adjustable. Preferably, the proportional valve according to the invention combines the functions of a poppet valve and a slide valve, so that in the de-energized state via the seat valve forming components a seal with minimal leakage can be reached and in fully energized state on the slider valve forming components accurate metering of the working medium can be realized which requires a comparatively low use of magnetic force. Further preferably, two sealing principles are combined. In the de-energized state, the seal is made via the seat valve, which is preferably formed by a conical valve seat and a conical sealing surface on the valve member. The seat valve is not pressure balanced in this case. In the fully energized state, a seal is effected via the slide valve, which is preferably formed by the sleeve-shaped diaphragm connected to the valve member in conjunction with its guide in the valve body. The slide valve is pressure compensated.

Preferred embodiments of the invention are explained in more detail below with reference to the attached drawings. These show:

1 shows a schematic longitudinal section through a proportional valve according to the invention according to a first preferred embodiment, FIG. 2 shows a schematic longitudinal section through an inventive proportional valve according to a second preferred embodiment and

Fig. 3 is a schematic longitudinal section through a proportional valve according to the invention according to a third preferred embodiment. Detailed description of the drawings

The proportional valve shown schematically in FIG. 1, of which only the valve part is shown, comprises a valve body 1 with a central bore 2, in which an axially adjustable valve member 3 is received. The axially adjustable valve member 3 has a piston-shaped and a plate-shaped portion, the latter serving to form a sealing surface 5. The sealing surface 5 is in the present case designed conical and cooperates with a likewise conical valve seat 4 which is formed within the bore 2 of the valve body 1. The bore 2 is designed for this purpose as a stepped bore, wherein the step forms an obliquely with respect to a longitudinal axis A extending paragraph, which serves as a valve seat 4.

The valve seat 4 faces a region of the bore 2 serving as an inlet 6, in which a spring 8 for the axial prestressing of the valve member 3 is arranged against the valve seat 4. For this purpose, the spring 8 is supported, on the one hand, on an end surface 15, remote from the sealing surface 5, of the valve member 3 and, on the other hand, on an annular securing element 9, which is pressed into the bore 2. For radial positional fixation of the spring 8, the end face 15 is stepped. Since the spring 8 receiving portion of the bore 2 serves as an inlet 6, the valve member 3 is acted upon in the direction of the valve seat 4 not only by the spring force of the spring 8, but also via a hydraulic or pneumatic pressure force resulting from the on the valve member. 3 applied hydraulic or pneumatic pressure results. This has an advantageous effect on the tightness of the proportional valve.

In addition to the valve part, the proportional valve further comprises a magnetic part, which in the present case, however, is not shown in detail. In the magnet part, an electromagnet is accommodated for acting on a liftable armature, which in turn is connected to a plunger 14 for actuating the valve member 3. The plunger 14 is mechanically coupled or coupled with the valve member 3 for this purpose.

When the electromagnet is energized, the armature and the plunger 14 move in the direction of the valve seat 4, wherein the plunger 14 presses the valve member 3 from the valve seat 4. The present designed as a pure seat valve proportional valve opens, so that a connection of the inlet 6 is made with a drain 7, which comprises a plurality of radially extending bores 11, which open into the bore 2. Since the piston-shaped portion of the valve member 3 has a reduced outer diameter in the region of the bores 11, the working medium can flow from the inlet 6 via the valve seat 4 to the outlet 7. About the adjoining piston-shaped portion, the valve member 3 is guided in the bore 2.

FIG. 2 shows a further preferred embodiment of a proportional valve according to the invention. This differs from that of FIG. 1 in that the valve member 3 is connected to a substantially sleeve-shaped aperture 12, which has circumferentially formed apertures 13, which can be brought into overlap with the holes 11 serving as a drain 7. The opening into the bore 2 holes 11 form from control edges 16, which determine the free flow cross section of the openings 13 and consequently the flow.

The proportional valve of FIG. 2 is not formed in contrast to that of FIG. 1 as a pure seat valve. It rather represents a combination of slide and seat valve. This has the advantage that high demands are met both on the tightness and the positioning accuracy.

In the example of FIG. 2, the guide of the valve member 3 is effected in the bore 2 via the aperture 12. The diaphragm 12 also serves the mechanical coupling with the plunger 14th

The shape of the openings 13 is selected in the embodiment according to FIG. 2 such that, depending on the axial position of the diaphragm 12, the flow rate can be varied in such a way that a non-linear flow characteristic can be displayed. For this purpose, the openings 13 each have a triangular basic shape, which merges into a narrow slot. The shape of the openings 13, however, can basically be chosen arbitrarily.

FIG. 3 shows a further preferred embodiment of a proportional valve according to the invention. In a further development of the embodiment of Fig. 2 is in the valve seat 4 is used an elastically deformed Bares sealing element 10, which thus forms the actual valve seat 4. The sealing element 10 optimizes the sealing seat of the valve member 3, so that the tightness is further improved.

The sealing element 10 shown in FIG. 3 can also be combined with the embodiment of FIG. 1.

In FIG. 3, moreover, the flow direction of the working medium is shown by means of the arrows 17. The arrow 18 indicates the magnetic force of the electromagnet, not shown. The same forces also act in the proportional valves shown in FIGS. 1 and 2, so that insofar as the representation of FIG. 3 is transferable.

Proportional valves of the type described above for controlling the flow of liquid or gaseous media are versatile, for example in the field of vehicle technology for quantity control of fuel in a fuel injection system. A proportional valve, also referred to as a "metering unit", is usually connected upstream of an inlet valve of a high-pressure fuel pump in order to supply the latter with sufficient fuel, but with zero delivery it is desirable that no fuel enters the working space of the high-pressure fuel pump is basically unavoidable, a "real" zero funding can not be guaranteed.

Here, the proportional valve according to the invention provides a remedy because it meets very high demands on the tightness and thus allows a "real" zero delivery .This has the consequence that a possibly further provided pressure relief valve of the fuel injection system can be omitted alternatively or additionally be dispensed with a return port for returning a leakage amount.

Claims

claims

1. Electromagnetically actuated proportional valve for controlling the flow of a working medium, comprising a valve body (1) having a bore (2) in which at least partially a valve member (3) is received, which cooperates with a valve seat (4) sealing surface (5) has and is axially adjustable to connect an inlet (6) with a drain (7),

characterized in that the valve member (3) via the spring force of a spring (8) against the valve seat (4) is axially biased.

2. Proportional valve according to claim 1,

characterized in that the spring (8) arranged in the bore (2) and / or axially fixed in position via a securing element (9), which is preferably pressed into the bore (2).

3. Proportional valve according to claim 1 or 2,

characterized in that the spring (8) is arranged in a serving as an inlet (6) portion of the bore (2) to which preferably for forming the valve seat (4) has a radially and / or obliquely with respect to a longitudinal axis (A ) extending paragraph of the bore (2) connects, which further preferably leads to a reduction of the inner diameter of the bore (2) in the flow direction of the working medium.

4. Proportional valve according to one of the preceding claims,

characterized in that in the valve seat (4) and / or in the sealing surface (5) of the valve member (3) an elastically deformable sealing element (10) is inserted.

5. Proportional valve according to one of the preceding claims, characterized in that the valve body (1) has at least one serving as a drain (7), radially or obliquely extending bore (11) which opens into the bore (2).

6. Proportional valve according to one of the preceding claims,

characterized in that the valve member (3) has a substantially hülsenförmi- ge aperture (12) or is connected to a substantially sleeve-shaped aperture (12), wherein the substantially sleeve-shaped aperture (12) is preferably formed as a slit and at least one in overlapping with the sequence (7) can be brought coat-side opening (13).

7. Proportional valve according to claim 6,

characterized in that the aperture (13) has an increasing or decreasing in the axial direction flow cross-section.

8. Proportional valve according to one of the preceding claims,

characterized in that the electromagnetic actuation indirectly via a plunger (14) via which the valve member (3) can be acted upon with an axial force, which is preferably set opposite to the spring force of the spring (8).

9. Proportional valve according to one of the preceding claims,

characterized in that the spring (8) is supported on an end face of the valve member (3), which is preferably designed stepped for radial positional fixation of the spring (8).

10. Proportional valve according to one of the preceding claims,

characterized in that the proportional valve is normally closed, wherein on the axial biasing force of the spring (8), the opening pressure of the proportional valve is adjustable.

11. Proportional valve according to one of the preceding claims,

characterized in that it combines the functions of a poppet valve and a slide valve, so that in the de-energized state via the components forming the seat valve, a seal with minimal leakage can be achieved and in fully energized

State over the slider valve forming components accurate metering of the working medium can be realized, which requires a relatively small use of magnetic force.