GB2305217A

GB2305217A - Solenoid valve, for controlling pressure media, having coaxial housing parts centred by a sleeve

Info

Publication number: GB2305217A
Application number: GB9616188A
Authority: GB
Inventors: Willi Frank
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1995-09-13
Filing date: 1996-08-01
Publication date: 1997-04-02
Anticipated expiration: 2016-08-01
Also published as: GB2305217B; JPH09119554A; DE19533786A1; DE19533786B4; GB9616188D0

Description

2305217 - 1 -.

DESCRIPTION

SOLENOID VALVE FOR THE PURPOSE OF CONTROLLING PRESSURE MEDIA The invention relates to a generic type of claim 1. position solenoid valve as valve member is designed it is necessarv that on solenoid valve according to the In the case of such a 3 port, 2 disclosed by DE-A-22 17 655 the having two parts. To this end its one end side a compression spring is provided which reliably holds together the two valve member parts in position against each other. In addition this is supported by virtue of a predetermined and very expensive provision of pressure compensation bores. The assembly of this known valve is basically already very expensive due to the fact that it has two parts.

Advantages of the Invention The solenoid valve in accordance with the invention ensures that the valve member can be designed as a single piece and can therefore be produced in a particularly advantageous manner. This guarantees that the guide bore, the valve seats, the axis of the valve member and its sealing surfaces can be disposed coaxially to each other with greater precision and thus in a simple assembly of the solenoid valve a great degree of operatability is achieved. In particular the arrangement of the centring sleeve on the outer surface of the first housing part and the second housing part guarantees this coaxiality. In the case of the individual housing parts the outer surface can be ground in an advantageous manner in a single clamping in a machine tool and simultaneously the guide bore can be produced in the final tolerance. Therefore in the assembly with the centring sleeve all axes of the elements involved, which have sealing functions, coincide exactly.

An exemplified embodiment of the invention is shown in the drawing and explained further in the description hereinunder. Figure 1 shows a sectional view through the solenoid valve in accordance with the invention, figure 2 shows a sectional view through the centring ring and figure 3 shows an enlarged partial view of the centring ring.

Description of the exemplified embodiment

The solenoid valve illustrated in figure 1 in the longitudinal sectional view comprises in a known manner an electromagnet 1 having an armature 2, which is connected securely to a valve member 3 and, as the electromagnet is - 3 excited, moves said valve member, against the force of a restoring spring 4, upwards with respect to the view of the drawing.

The valve member 3 is guided in a f irst guide bore 8 which is disposed with a circular-shaped cross section coaxially with respect to the axis of a first housing part 6. The first housing part comprises a stepped form having a first regular cylinder 9 of smaller diameter facing the armature 2 and having a second regular cylinder 10 of larger diameter remote from the armature. On the shoulder which forms at the transition of the regular cylinders the housing part is fixed axially to a correspondingly designed shoulder 11 of the valve housing 12. An end face 15 of a second housing part 16 lies in a tight f itting manner on the end face 14 of the larger in diameter regular cylinder 10 of the first housing part. This second housing part also has a cylindrical form comprising a first regular cylinder part 18 of smaller diameter and a second regular cylinder part 19 of larger diameter. The first regular cylinder part 18 has the same diameter as the second regular cylinder 10 of the first housing part 6. In addition the second housing part comprises a coaxial blind bore 21 as a second guide bore 21 for the valve member 3. This blind bore is precisely coaxial with respect to the first guide bore 8.

The second housing part is connected by means of a centring sleeve 22 to the first housing part, wherein the centring sleeve 22 is pressed partly on the outer surface of the first regular cylinder part 18 and partly on the outer surface of the second regular cylinder 10 of the first housing part. Since both regular cylinders have the same diameter which was worked with high precision and places its middle point in the axis of the first guide bore 8 or the second guide bore 21, an exact alignment of the bores in the two housing parts 6 and 8 [sic] is guaranteed.

The second housing part 16 lies with its level end face of the second regular cylinder part 19 on a correspondingly level end face of a further housing part 23 onto which the valve housing 12 is screwed for the purpose of clamping firmly the first and second housing parts 6 and 16. Consequently the housing parts are fixed exactly in axial series with a tight seal on the end face.

In the further housing part a valve needle 25 of an injection valve is disposed of which said valve needle only the upper control piston 26 is shown. This closes with its end face a pressure chamber 27 which is acted upon by or relieved of high pressure corresponding to the control of Accordingly the valve needle 25 is moved to an open-position or a closedposition.

To this end the pressure chamber 27 is connected by way of an axially parallel pressure line 29 in the second housing part 16 and a sub line 30 in the first housing part 6 to a chamber 31, which is enclosed on the one side by a blind bore issuing from the end face 14 of the first housing part 6 and by the end face 15 of the second housing part 16. Likewise the chamber 31 lies coaxially with respect to the guide bores 8 and 21 and receives a part, enlarged in the solenoid valve - 5 diameter with respect to the diameter of the guide bores 8 and 21, of the valve member in the form of a collar 33. At said part of the valve member on its side facing the armature 2 a first sealing surface 34 is disposed and on its side lying opposite a second sealing surface 35 is disposed, which first sealing surface cooperates with a first valve seat 36 formed at the point where the guide bore 8 exits from the first housing part 6 into the chamber 31. The second sealing surface 35 cooperates with a second valve seat 37 formed at the point where the second guide bore 21 exits at the end face 15 of the second housing part. Towards the armature 2 following an from the collar 33 the diameter of the valve member is reduced, thus forming an annular shaped chamber, by way of which chamber, pressure medium, which can flow to the valve seat 36 by way of a pressure line 28 which issues into the first guide bore 8 [sic]. When the valve member is moved downwards and lies on the second valve seat, pressure medium thus flows into the chamber 31 and flows therefrom further by way of the sub line 30 and the pressure line 29 into the pressure chamber 27.

The collar 33 becomes a valve member part with reduced diameter at its end remote f rom the armature 2 and a guide piston 39 follows on then from said valve member part. Above this guide piston a connection 42 exists to the chamber which is enclosed by the end face 40 of the guide piston in the blind bore 21, which chamber is relieved of pressure in turn by way of a relief line 41. If the valve member 3 is then moved upwards by the armature 2 the pressure chamber 27 can be relieved by way of the chamber 31, the blind bore 21 and the relief line 41. In this case the valve needle 25 can arrive at the open- position. if fuel brought to injection pressure is used as a pressure medium the pressure line 28 will then also be supplied with pressure from this high pressure fuel source, which pressure is supplied by way of the line 45 which continues from the pressure line 28 to a pressure chamber [not illustrated further] of the fuel-injection valve which borders onto the valve needle 26.

Due to the predetermined form of the housing parts 6 and 16 a highly precise coaxiality of the outer surface of the second regular cylinder 10 is produced with respect to the first guide bore 8 and likewise is the case of the outer surface of the first cylinder part 18 with respect to the axis of the second guide bore 21. The guide bores and the outer peripheries of these two housing parts are produced in a single clamping in a processing machine so that none of the machine tolerances whatsoever influence the exact coaxiality. Subsequently this coaxiality is fixed during the final assembly with the aid of the centring ring 22. The centring ring can be rounded at its run-up ends of its inner bore 43 (Figure 2) with a subsequent run-up cone 44 as the detail illustration in Figure 3 shows. In particular the ring can be applied to the housing parts with a high force fit after preheating.

RDQ44U)C8

Claims

1. Solenoid valve for the purpose of controlling pressure media having a valve member actuated by an electromagnet, which valve member is guided in a housing which consists of a first housing part provided with a first guide bore for the valve member and of a second housing part provided with a second guide bore for the valve member, which housing parts comprise respectively a cylindrical outer surface of equally sized diameter, which are held in a common inner bore of a part of the solenoid valve and in the first housing part at the end of the first guide bore are formed a first valve seat and, in the second housing part at the end of second guide bore, a second valve seat which lies opposite to said first valve seat, onto which a corresponding first sealing surface or second sealing surface on the valve member can be placed into a scaling position according to the position of the valve member and a pressure medium supply is provided upstream of the first valve seat, between the valve seats a chamber is provided in the housing from which a connection line) leads off, and a connection line to a relief chamber exists downstream of the second valve seat on its side remote from the chamber, characterised in that the valve member is designed as a single piece having a middle collar on which the first and the second sealing surfaces are disposed on sides remote from one another and on the cylindrical outer surface of the two housing parts a centring sleeve sits as the part of the solenoid valve which comprises the common inner bore and the two housing parts are held tightly against each other in the valve housing by means of axial clamping forces.

2. Solenoid valve according to claim 1, characterised in that the centring ring is dimensioned in diameter in such a way that it is applied in the form of a force fit on the outer surfaces of the housing parts.

3. Solenoid valve according to claim 1, characterised in that the centring ring is rounded in design at the ends of its inner bore.

4. Solenoid valve according to claim J3), characterised in that the rounded region is combined with a run-up slope.

5. Solenoid valve constructed and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.