Hydraulic overpressure valve and hydraulic machine

Abstract

A hydraulic overpressure valve (1) is provided comprising a valve housing (2), a valve seat (3) located in said valve housing and having a seat center and a seat center axis (4), a cone element (5) movable relatively to said valve seat (3), said cone element (5) having a cone (6) protruding at least partly into said valve seat (3) and having a cone center axis (4), and force generating means acting on said cone element (5) in a direction towards said valve seat (3). Such a hydraulic overpressure valve should be operated with low noise. To this end said cone (6) is movable along a path of movement in which said cone center axis is kept outside said seat center axis (4).

Claims

1. A hydraulic overpressure valve comprising: a valve housing; a valve seat located in said valve housing and having a seat center and a seat center axis; a cone element movable relative to said valve seat, said cone element having a cone protruding at least partly into said valve seat and having a cone center axis; and force generating means acting on said cone element in a direction towards said valve seat, wherein said cone is movable along a path of movement in which said cone center axis is kept outside said seat center axis; wherein said force generating means comprise at least a spring; wherein an arrangement of said spring and said cone element produces lateral forces on said cone element with respect to said cone center axis; wherein said spring comprises two ends faces, one of said two end faces resting against a first spring support area of said cone element and the other one of said two end faces resting against a second spring support area located in said valve housing; and wherein said two end faces and said first and second spring supporting areas deviate from a plane which is perpendicular to said seat center axis.

2. The valve according to claim 1 wherein said cone is loaded with a lateral force perpendicular to said cone center axis.

3. The valve according to claim 2, wherein said lateral force is generated by said force generating means.

4. The valve according to claim 1, wherein an arrangement of said spring and said cone element producing lateral forces on said cone element with respect to said cone center axis.

5. The valve according to claim 4, wherein at least one of said end faces and said spring support areas is slanted relative to said plane.

6. The valve according to claim 5, wherein at least one of said end faces and said spring support areas has a form different from a plane.

7. The valve according to claim 4, wherein at least one of said end faces and said spring support areas has a form different from a plane.

8. The valve according to claim 7, wherein at least one of said end faces and said spring support areas has a recess area.

9. The valve according to claim 8, wherein said recess area extends in circumferential direction up to 180?.

10. The valve according to claim 8 wherein said recess area is grinded.

11. The valve according to claim 10, wherein said recess area extends in circumferential direction up to 180?.

12. A hydraulic machine comprising a hydraulic overpressure valve according to claim 1.

13. The hydraulic machine according to claim 12, wherein said hydraulic machine is a hydraulic steering unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments of the invention will now be described in more detail with reference to the drawing, wherein:

(2) FIG. 1 shows a first embodiment of a hydraulic overpressure valve,

(3) FIG. 2 shows a second embodiment of a hydraulic overpressure valve,

(4) FIG. 3 shows a third embodiment of a hydraulic overpressure valve, and

(5) FIG. 4 shows a fourth embodiment of a hydraulic overpressure valve.

DETAILED DESCRIPTION

(6) FIG. 1 shows schematically an overpressure valve 1 comprising a housing 2 and a valve seat 3 located in said valve housing 2. The valve seat 3 has a seat axis 4 running through a seat center.

(7) A cone element 5 comprises a cone 6. The cone 6 protrudes partly into the valve seat 3. The cone element 5 has a cone axis which is not shown separately.

(8) Force generating means comprising a spring 7 act onto the cone element 5 in a direction towards the valve seat 3. The spring 7 is located between the cone element 5 and a plug 8 which is mounted in the housing 2. The respective parts are shown exploded for the sake of clarity.

(9) A ring gap 9 is provided between the cone element 5 and the housing 2. The cone element 5 and the cone 6 are not guided.

(10) The spring 7 comprises a first end face 10 and a second end face 11. When the parts shown are assembled correctly, the spring 7 contacts a first spring support area 12 on the cone element 5 and a second spring support area 13 on the plug 8.

(11) In the embodiment of the hydraulic overpressure valve 1 shown in FIG. 1 the two end faces 10, 11 form an angle with a theoretical plane which is perpendicular to the seat axis 4. In other words, the end faces 10, 11 are not perpendicular to the seat axis 4.

(12) This has the effect that the cone element 5 is loaded with a greater force on the left hand side (as shown in FIG. 1) than on the right hand side so that when the cone element 5 is lifted from the valve seat 3 and the cone is moved in a direction out of the valve seat 3 there is a lateral force acting on the cone element moving the cone center axis out of the seat center axis.

(13) The inclination of the end faces 10, 11 is in reality not as big as that shown in FIG. 1. FIG. 1 shows a large angle for the sake of clarity.

(14) The spring with the slanted end faces 10, 11 produces a lateral force which is perpendicular to the cone center axis to press and move the cone element 5 out of a center position with respect to the valve seat 3. This is simple be realized by means of an asymmetric construction of the arrangement of spring 7 and cone element 5.

(15) Basically it would be sufficient to have only one of the end faces 10, 11 slanted.

(16) The two end faces 10, 11 are slanted or inclined in opposite directions.

(17) FIG. 2 shows a second embodiment in which the elements described in connection with FIG. 1 are designated with the same reference numerals. In this embodiment the two end faces 10, 11 of the spring 7 are parallel to each other and are perpendicular to the seat axis 4.

(18) In order to produce the lateral forces onto the cone element 5 the spring support areas 12, 13 are inclined with respect a plane which is perpendicular to the seat axis 4 producing the same effect as the inclined end faces 10, 11 shown in FIG. 1.

(19) It is possible to combine the two embodiments of FIGS. 1 and 2, i.e. to have one or two inclined end faces 10, 11 and one or two spring support areas 12, 13. As shown in FIG. 4, in this case the end face 10 and the corresponding spring support area 12 should be inclined in opposite directions and the end face 11 and the spring support area 13 should be inclined in opposite directions as well. The inclination of the spring support areas 12, 13 is opposite as well.

(20) FIG. 3 shows another embodiment of a hydraulic overpressure valve in which elements which have been described in connection with FIGS. 1 and 2 are designated with the same reference numerals.

(21) The asymmetric construction of the arrangement of spring 7 and cone element 5 is realized in this case by a recess area 14 formed in the end face 10 of spring 7. This recess area 14 can be produced by grinding. The recess area 14 extends in circumferential direction over less than 180?, preferably over 100? or less. In a particular preferred embodiment it extends over 50??20?.

(22) When such a recess area 14 is provided, the corresponding end face 11 does no longer have the form of a plane. The plane is disturbed by the recess area 14. Although not shown, it is possible that both end faces 10, 11 are provided with a recess area 14.

(23) It can also be the case that a recess area is provided in the spring support areas 12, 13 in such a way that the spring 7 does not contact the cone element 5 or the plug 8 in the recess area 14.

(24) Such a hydraulic overpressure valve can preferably be used in a hydraulic machine, in particular in a hydraulic steering unit. It can be used to reduce or limit a full hydraulic pressure or to reduce or limit a pilot pressure.

(25) While the present disclosure has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this disclosure may be made without departing from the spirit and scope of the present disclosure.