PROPORTIONAL SPOOL VALVE FOR ADJUSTING THE DISPLACED VOLUME OF A DISPLACEMENT PUMP, ASSEMBLY METHOD AND SYSTEM

Abstract

A proportional spool valve (1) for adjusting a displaced volume of a displacement pump, in particular of an oil pump in a motor vehicle, the proportional spool valve (1) includes a valve housing (2) and a valve spool (3) which is mounted in the valve housing (2) and displaceable along a displacement axis (V) and which can be displaced against the spring force of a valve spring (6) axially supported on a spring holder (7) which is fixed relative to the valve housing (2) by energizing an electrical coil assembly (10), characterized in that wherein both the preferably single-piece spring holder (7) and the valve housing (2) are made of plastic and that the spring holder (7) is welded to the valve housing (2), an integral welded connection (9) being formed.

Claims

1. A proportional spool valve (1) for adjusting a displaced volume of a displacement pump, the proportional spool valve (1) comprising a valve housing (2) and a valve spool (3) which is mounted in the valve housing (2) and displaceable along a displacement axis (V) and which can be displaced against the spring force of a valve spring (6) axially supported on a spring holder (7) which is fixed relative to the valve housing (2) by energizing an electrical coil assembly (10), wherein both the spring holder (7) and the valve housing (2) are made of plastic and the spring holder (7) is welded to the valve housing (2), an integral welded connection (9) being formed.

2. The proportional spool valve according to claim 1, wherein the spring holder (7) and the valve housing (2) overlap in the radial direction.

3. The proportional spool valve according to claim 1, wherein the spring holder (7) has at least one spool section (17, 18) which extends outwards in the radial direction and which, in a circumferential direction, is welded to a valve housing section (19, 20, 21, 22) in the form of a ridge projecting outwards in the radial direction.

4. The proportional spool valve according to claim 3, wherein the spool section (17, 18) is sandwiched between two valve housing sections (19, 20, 21, 22) which are spaced in the circumferential direction, and is welded to both valve housing sections (19, 20, 21, 22) by full penetration welding in the circumferential direction, or wherein the spool section (17, 18) is welded to a valve housing section (19, 20, 21, 22), in particular to a ridge projecting outwards in the radial direction, exclusively in a circumferential direction.

5. The proportional spool valve according to claim 3, wherein the spool section (17, 18) and the valve housing section (19, 20, 21, 22) are welded to one another over the entire surface or at spaced weld spots which are defined by a surface structure of the spool section (17, 18) and/or of the valve housing (2).

6. The proportional spool valve according to claim 3, wherein the spring holder (7) has at least two, spool sections (17, 18) which are each welded to at least one valve housing section (19, 20, 21, 22).

7. The proportional spool valve according to claim 1, wherein the spring holder (7) and the valve housing (2) are exclusively, welded to one another at radially opposed circumferential contact surfaces.

8. The proportional spool valve according to claim 1, wherein an axial stop at the valve housing (2) is assigned to the spring holder (7) in order to limit the axial sliding insertion movement of the spring holder (7) into the valve housing (2) during assembly.

9. The proportional spool valve according to claim 1, wherein the spring holder (7) limits an axial through-flow channel (8) which communicates with a pressure connection (P) of the proportional spool valve (1) and/or wherein the valve spool (3) has surfaces (4, 5) for a displacement pressure of a displaced fluid, which are opposed to one another and which differ in size to create a differential force which counteracts on the valve spool (3) of the valve spring (6) according to the size difference of the effective surfaces (4, 5).

10. A method for assembling a proportional spool valve (1) according to claim 1, wherein comprising the steps: providing the spring holder (7) and the valve housing (2) and a valve spring (6) inserting the valve spring (6) and the spring holder (7) into the valve housing (2) fixing the spring holder (7) to the valve housing (2), wherein the spring holder (7) made of plastic and the valve housing (2) made of plastic are fixed to one another by welding, in particular by ultrasonic welding or by laser welding, an integral welded connection (9) being formed.

11. The method according to claim 10, wherein the spring bias of the valve spring (6) is adjusted by axially moving the spring holder (7) and the valve housing (2) relative to each other before the welding.

12. The method according to claim 10, wherein the spring holder (7) has at least one spool section (17, 18) which extends outwards in the radial direction and which, in a circumferential direction, is welded to a valve housing section (19, 20, 21, 22).

13. The method according to claim 12, wherein the spool section (17, 18) is sandwiched between two valve housing sections (19, 20, 21, 22) spaced in the circumferential direction, and said spool section is welded to both valve housing sections (19, 20, 21, 22), by full penetration welding of at least one of the valve housing sections (19, 20, 21, 22) in the circumferential direction.

14. The method according to claim 12, wherein the spool section (17, 18) is welded, exclusively in a circumferential direction, to a valve housing section (19, 20, 21, 22), under simultaneous application of contact pressure to the spool section (17, 18) in the circumferential direction by means of an anvil, against the valve housing section (19, 20, 21, 22) from a side of the spool section (17, 18) facing away from the valve housing section (19, 20, 21, 22).

15. The method according to claim 10, wherein the spring holder (7) and the valve housing section (19, 20, 21, 22) are welded to one another exclusively at circumferential contact surfaces opposing each other in the radial direction.

16. An oil pumping system in a motor vehicle, comprising a displacement pump which has an adjustable displaced volume impeller pump and a proportional spool valve (1) according to claim 1, the system being configured and disposed to adjust the displaced volume of the displacement pump.

17. The proportional spool valve according to claim 4, wherein the two valve housing sections are ridges projecting outwards in the radial direction.

18. The method according to claim 10, wherein the valve housing section is a ridge projecting outwards in the radial direction.

19. The method according to claim 13, wherein the two valve housing sections are two ridges projecting outwards in the radial direction.

20. The proportional spool valve according to claim 1, wherein the displacement pump is an oil pump of a motor vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Further advantages, features and details of the invention can be derived from the following description of preferred exemplary embodiments and from the drawings.

[0032] In the following,

[0033] FIG. 1 is a longitudinal sectional view of a preferred exemplary embodiment of a proportional spool valve formed according to the idea of the invention for adjusting a displaced volume of a displacement pump,

[0034] FIG. 2a is a detailed view of a possible embodiment of the proportional spool valve according to FIG. 1, a welded connection effective in the circumferential direction being realized between two diametrically opposed spool sections and two radially projecting housing sections in the form of ridges opposed in the circumferential direction,

[0035] FIG. 2b is a version of the exemplary embodiment according to FIG. 2a for realizing selective welded connections,

[0036] FIG. 3a and

[0037] FIG. 3b are different views of an alternative embodiment of a proportional spool valve formed according to the idea of the invention, the spool sections being welded to a radially projecting housing section in the form of a ridge, the welded connection being effective in the circumferential direction at one side only, and

[0038] FIG. 4a and FIG. 4b are different views of an additional alternative embodiment of a proportional spool valve formed according to the idea of the invention, a welded connection effective exclusively in the radial direction being realized between the spring holder and the valve housing.

[0039] In the figures, the same elements and elements having the same function are referenced with the same reference numerals.

DETAILED DESCRIPTION

[0040] In FIG. 1, an exemplary embodiment of a proportional spool valve 1 formed according to the idea of the invention for adjusting a displaced volumean oil volume in the case at handof a displacement pump such as a vane pump (not shown) is illustrated.

[0041] Proportional spool valve 1 comprises a valve housing 2 made from plastic in which a valve spool 3 is mounted so as to be displaceable along a displacement axis V.

[0042] In the case at hand, proportional spool valve 1 is configured as a 4/3-way valve and comprises an axial pressure connection P at the end face which is connected to the pressure side of an oil circuit comprising a displacement pump within the scope of the system. In valve housing 2, proportional spool valve 1 also comprises a tank connection T at the wall, which is connected to a low pressure side of the oil circuit or to an oil reservoir. Furthermore, proportional spool valve 1 comprises two working connections A, B which can be connected, preferably alternately, to the pressure connection P and the tank connection T by displacing valve spool 3 in order for two pressure chambers of the displacement pump to be supplied with oil pressure or to be connected to the low pressure side to adjust the displaced volume, thereby causing an adjustment of an actuator of the displacement pump and manipulating the displaced volume. Proportional spool valve 1 can alternatively be realized as a 3/2-way valve having a single working connection if instead of two pressure chambers acting against one another being provided in the displacement pump, the actuator can be adjusted against the spring force of a return spring by means of a single pressure chamber.

[0043] In the case at hand, valve spool 3 comprises a first and a second displacement-effective (axial) surface 4, 5, first effective surface 4 being larger than second effective surface 5, a fluid force component thus acting along displacement axis V against the spring force of a valve spring 6 which is axially supported by valve spool 3 at one end and, at the other end, by a spring holder 7 made from plastic which is disposed directly downstream of pressure connection P and which has a through-flow channel 8 to direct the fluid, oil in the case at hand, towards valve spool 3, i.e. towards working connections A, B. According to the invention, spring holder 7 is welded to valve housing 2 by means of an integral welded connection 9.

[0044] To displace valve spool 3 between the different adjustment or axial positions, the proportional spool valve comprises a preferably PWM-actuated coil assembly 10 which can be actuated via an electrical contact connection 11. By energizing coil assembly 10, an armature 12 surrounded in sections by coil assembly 10 is displaced against a plunger 13 to the right in the drawing plane, said plunger 13 interspersing a magnetic core 14 towards valve spool 3 in order to adjust valve spool 3. A yoke 15 spaced from core 14 is assigned to armature 12 for closing the magnetic circuit.

[0045] For the assembly of proportional spool valve 1, valve spool 3, valve spring 6 and spring holder 7 are inserted into valve housing 2 through an end-face or axial insertion opening 16 at the right side of the drawing plane. Spring holder 7 is axially displaced by measuring the pressure ratios at at least one of connections A, B, T when coil assembly 10 is energized and a pressure at the pressure seal is known until the desired target pressure is reached at the corresponding connection, whereupon the integral welded connection 9 is formed. In this regard, there are also different possibilities.

[0046] In an exemplary embodiment shown in FIG. 2, which shows a diagonal view of insertion opening 16, spring holder 7 comprises two diametrically opposed spool sections 17, 18 which are axially displaced along displacement axis V relative to valve housing 2. Each spool section 17, 18 is formed in a single piece with the remaining spring holder 7, which is a radially inner hollow cylinder in the case at hand. In the circumferential direction, spool sections 17, 18 are each accommodated between two valve housing sections 19, 20, 21, 22 which are spaced in the circumferential direction and which are formed as ridges projecting radially outwards beyond a hollow cylindrical section of the valve housing which accommodates spring holder 7. Depending on the embodiment or realization of the welding method, it is possible to weld each of the spool sections 17,18 to only one of the assigned valve housing sections 19, 20, 21, 22 or to both valve housing sections 19, 20, 21, 22, in particular by full penetration welding, which comprises inserting a welding probe, preferably a multi-pen ultrasonic probe, in the circumferential direction through a valve housing section 19, 20, 21, 22 as far as into the associated spool section 17, 18, preferably beyond said spool section and into the opposite valve housing section 19, 20, 21, 22. If the opposite surfaces of spool sections 17, 18 and valve housing sections 19, 20, 21, 22 are unstructured, a welded connection 9 is realized substantially across the entire surface. Alternatively, an exemplary embodiment shown in FIG. 2b can be realized, in which spool section 17 and valve housing section 20 do not contact one another over the entire surface; instead, the surface structure is such that selective and preferably spaced welded connections 9 result.

[0047] The exemplary embodiments shown in FIGS. 2a and 2b are characterized in that valve housing 2 and spring holder 7 overlap in the radial direction and that welded connection 9 is realized at contact surfaces opposing each other in the circumferential direction.

[0048] FIGS. 3a and 3b show an additional alternative embodiment comprising a spring holder 7 and a valve housing 2 overlapping in the radial direction. By analogy with the exemplary embodiment according to FIGS. 2a and 2b, spring holder 7 is provided with two spool sections 17, 18 which are diametrically disposed and which extend or project in opposite radial directions; however, only one valve housing section 20, 21 in the form of a ridge and projecting radially outwards beyond an essentially hollow cylindrical valve housing section is assigned to each spool section 17, 18, a welded connection thus being realized at one side only. During welding, force is applied to each of the spool sections 17, 18 in the direction of arrow R by means of an anvil (not shown) and spool sections 17, 18 are pressed against a contact surface of the associated valve housing section 20, 21 located opposite in the circumferential direction to improve the formation of welded connection 9. If an ultrasonic welding method is realized, the welding is preferably realized in such a manner that valve housing sections 20, 21 are each penetrated with a welding probe, in particular a multi-pen ultrasonic probe, from the circumferential side facing away from the anvil as far as into the associated spool section 17, 18 and that the integral welded connection is thus realized.

[0049] The exemplary embodiment according to FIGS. 4a and 4b to be described below can be realized in addition or as alternative to the aforementioned embodiments or welded connections 9. In contrast to the above-described embodiments, spring holder 7 has no radially projecting spool sections 17, 18; however, they can be realized, if required. In the case at hand, the welding is realized in the radial direction or, more precisely, between two circumferential contact surfaces opposite in the radial direction at outer circumference 23 of spring holder 7 on the one hand and, on the other hand, at opposite radially inner circumference 24 of valve housing 2 which extends in the circumferential direction like outer circumference 23. In FIG. 4a, penetration points 25 can be seen which are caused by a multi-pen ultrasonic probe by means of which valve housing 2 has been penetrated in the radial direction as far as into spring holder 7 to form integral welded connection 9.

REFERENCE SIGNS

[0050] 1 proportional spool valve [0051] 2 valve housing [0052] 3 valve spool [0053] 4 first effective surface [0054] 5 second effective surface [0055] 6 valve spring [0056] 7 spring holder [0057] 8 through-flow channel [0058] 9 integral welded connection [0059] 10 coil assembly [0060] 11 contact connection [0061] 12 armature [0062] 13 plunger [0063] 14 core [0064] 15 yoke [0065] 16 insertion opening in the valve housing [0066] 17 spool section [0067] 18 spool section [0068] 19 valve housing section [0069] 20 valve housing section [0070] 21 valve housing section [0071] 22 valve housing section [0072] 23 outer circumference of the spring holder [0073] 24 inner circumference of the valve housing [0074] 25 penetration points [0075] A working connection [0076] B working connection [0077] P pressure connection [0078] R arrow direction(s) [0079] T tank connection [0080] V displacement axis