AU427407B2 - Improvements in control valves for hydraulic fluids - Google Patents

Description

ZL-, 652171 This invention relates to an improved

control valve of tihe kind in which a valve member

is normally urged against a seating in a housing

to cut off fluid flow by a pre-loaded spring

acting on the valve member through a push-rod.

assembly, and the push-rod assembly is movable

in an opposite direction away from the seating

by the armature of a solenoid, the push-rod

assembly being coupled to the armature by a lost-

motion connection.

According to our invention the lost-

motion connection comprises a first fixed abut-

ment in the housing, a second abutment on the

armature, engagement of the abutments limiting

the movement of the armature relative to the

push-rod assembly in the direction of the

seating, the abutments being free to remain in

engagement, and a stop limiting movement of

the push-rod assembly towards the seating, the

arrangement being such that, in closing the

valve, the push-rod assembly is stopped before

the abutments engage.

24, 5 2171 The stop limiting movement of the push-rod convenient- ly comprises the engagement between the valve member and the seating.

A longitudinal section through a control valve in accordance with our invention is illustrated in the single Figu- re of the accompanying drawings.

In the control valve illustrated 1 is a housing having a stepped cylindrical through-bore 2 of which portions of the bore are separated by a partition member 3 having a central opening 4. A chamber 5 defined in the bore between one face of the partition member 3 and one end of the housing is ,formed with a radial port 6 adapted to be connected to a return line to a reservoir for supplying fluid to a high pressure pump. The opposite face of the partition member 3 forms an abutment for the inner end of a cup-shaped sleeve 7 which is formed in its closed end with a central opening 8. The sleeve 7 is held in engagement with the partition member 3 by a plug 9. The plug 9 is screwed in a portion 10 of enlarged diameter at the opposite end of the bore 2.

A spacer member 11 having a central opening 12 of sub- stantial diameter is clamped between the sleeve 7 and an adjacent face of an annular member 13 of which the opposite face is in abutment with the inner end of the plug 9. The annular member 13 is provided with a central opening 14 of a diameter substan- tially equal to or slightly smaller than that of the opening 8. 4274 07

24, 6,)Zi~ The opening 14 is in communication with chamber 15 in the plug c for adapted to be connected to a source of high pressure fluid, by example, the pump or an hydraulic accumulator supplied

the pump, through a connection 16.

A valve member in the form of a ball 17 is located in

memb4 a chamber 18 disposed between the sleeve 7 and the annular

13 and defined by the opening 12. The ball 17 is adapted to en surrounding t] age with one of a pair of axially spaced seatings to an openings 8 andtli.Vhe chamber 18 is adapted to be connected

actuator for controlling a wheel brake slave cylinder throh

radial passage 19 in the member 11 and a communicating radial/p in the wall of the housing 1.

Normally the ball 17 is held against the seating the surrounding the opening 14 to cut-off communication between

hig h pressure source and the actuator by a push-rod assembly located in the chamber

The push-rod assembly comprises a cylindrical holder

from the inner end of which projects a stem 22 of reduced engae diameter which normally extends through the opening 8 and 23 e3 at its free end with the ball 17. A central axial recess receiv tending inwardly from the opposite end of the holder 21 stem in screw-threaded engagement, the outer end of a threaded nut 26 24 of an axi-ally extending actuating rod 25. A locking end of the screwed onto the.stem 24 abuts against the adjacent relatil holder 21 to lock the stem 24 and the holder 21 against 21 fo: rotation. The face of the nut 26 remote from the holder fon an abutment for a plate 27 of dished outline which in turn

an abutment for one end of a pre-loaded spring 28. The outer

opposite end of the spring 28 engages with an inwardly extendi.

radial abutment flange 29 engaging with a shoulder 30 at the b 4274 07

24, 652 /71 of an annular recess 31 in the wall of the housing I at that end in which the chamber5 is located. The flange 29 is integral with a ring 32 of an axial length equal to that of the recess 31. The outer end of the ring 32 is clamped in engagement with a casing 33 incorporating'solenoid windings (not shown) which surround an armature 34.

*The actuating rod 25 works through a central opening in a bushing 35 screwed 'into an axially extending recess 36 in the inner end of the armature 34. An enlarged head 37 carried by the inner end of the rod 25 is located in a chamber 38 defined' between the inner end of the recess 36 and the bushing 35. The head 37 is of an axi al length less than that of' the chamber 38 and of a diameter less than that of the recess 36. Th6 head 37 is/t4Ae axially movable relative to the armature 34 to form a lost-motion connection between the armature 34 and the actuating rod

An abutment ring 39 for engagement with the outer face of the flange 29 is carried by the armature 34 adjacent to its inner end.

In the position shown in the drawing in which the solenoid windings are de-energised the ring 39 engages with the flange 29 and the head 37 is spaced from the bushing 35. In that position the ball 17 is held against the seating/? to cut-off communication between the chamber 15 and the ports2O and 6 due to the influence of the spring 28.

When the solenoid windings are energised in response to a signal received from a control module sensing excessive deceleration of a braked wheel, the armature 34 is moved away 4 /74 U7

24. 65 271 from the housing I and, after the lost motion clearance between the head 37 and the bushing 35 has been taken-up, the armature withdraws the actuating rod 25 against the loading of the spring 28. This permits the ball 17 to move out of engagement with the seatingA and engagie th6 seatifig 8 due to the high pressure fluid supplied to the chamber 15 through the pbrt 16. That movement of the ball 17 places the chamber 15 in communica. tion with the port 20 so that fluid from the pressure source is supplied to the actuator.

When the solenoid windings are again de-energised, the pre-loaded spring 28 moves the actuating rod 25 in tht opposite direction taking with it the *armature 34 and the free end of the stem 22 acts on the ball 17 to urge it into engagement with the seating 14 which acts as a stop preventing further movement of the rod 25 in that direction. Due to the provision of the lost-motion connection any inertia applied to the armature 34 daring this movement is not transferred to the actuating rod but is taken by the flange 29 before relative movement between the head 37 and the armature 34 is sufficient to enable the head 37 to engage with the base of the recess 38.

When the control valve described above is incorporated in an hydraulic braking system, conveniently of the kind des- cribed in the Complete Specification of our Patent Application 10749170 ,5 Ij the connection 16 is connected to a source of high pressure fluid, the radial port 6 is connected to a return line to a reservoir for supplying fluid to the high pressure source through a union 40 screwed into a passage in the housing I and having an axial passage 42 in communication wi th the port 6, and the port 20 is connected to an actuator for controlling the pressure of hydraulic fluid applied to

24,65 2/71 at least one wheel brake. Preferably the actuator is of the

construction described in the Complete Specification of our

Patent Application Nos./ 5317/, '13811/70 ad 13815,70 cogmna e In normal operation of the hydraulic braking system the control

valve is in the position shown in the drawings with the solenoid

windings de-energised and the ball 17 held in engagement with the

seating 14 to cut-off communication between the source of

high pressure fluid and the actuator through the port 20. In that

position fluid can return from the actuator to the reservoir

through the ports 20 and 6 which are in communication by a flow

path in the housing 1 defined by the chamber 5, the opening 4,

the opening 8 in the sleeve 7, and the radial passage 19.

When the deceleration of the braked wheel exceeds a

predetermined value the solenoid windings are energised and the

armature 34 is withdrawn to permit the ball 17 to engage with

the seating 8 as.described above. Communication between the ports

and 6 is cut-off and high pressure fluid from the high pres-

sure source is then supplied to the actuator to relieve the

braking effort. Fluid within the chamber 5 and the opening 4

is then returned to the reservoir through the port 6 and the

communicating passage 42.

In such a hydraulic braking system a restriction may

be provided within the return line between the port 6 and the

reservoir. The provision of the restriction reduces the rate

at which hydraulic fluid is returned to the reservoir form the

actuator through the flow path in the housing 1 between the

ports 20 and 6, thereby controlling the rate of re-application

of the wheel brake.

In one construction the restriction comprises an

4 27.4 07

2 C 2 71 orifice formed in a plate which is located in the return line

at any convenient location. As illustrated in the drawings the restriction comprises an orifice 43 provided in a plate 44

disposed bet:.een the inner end of the union 40 and a shoulder

at the inner end of the passage 41 into which the union i I40 screwed.

This has the advantage that, by unscrewing the muion from the passage 41, the orifice plate 44 can be removed and replaced by a plate provided with an orifice of a different

diameter, whereby the characteristics of wheel brake re-applica-

tion can be controlled in accordance with the requirements of

any, or one particular, wheel brake bf a particular vehicle. For example, if the orifice plate is replaced by a plate provided

with an orifice of greater diameter the rate of re-application

of the wheel brake is increased. Similarly if the orifice plate is replaced by a plate provided with an orifice of lesser

diameter, the rate of re-application of the brake is decreased.

The selection of a particular orifice plate will depend entirely

upon the braking characteristics of a system in accordance with the

requirements of a vehicle in which it is to be installed.

The plate 44 is of a minimum thickness consistent with

enabling the plate to define an orifice 43 of a particular

diameter. Thus thePea44i of plate thickness to orifice diameter is maintained at a minimum value. At least the edge of the

plate 44 which defined th end of the orifice 43 remote from the

chamber 5 and facing the union 40 is of a sharp 900 outline.

The construction or orifice plate described above is of advantage in that its characteristics remain substantially

constant irrespective of changes in the viscosity of the S4 27 4 07 hydraulic fluid. 21t, 652,71 For example the orifice omerates satisfactory when the temperature of the hydraulic fluid is/az. low as

4274 07

Claims (4)

1. 2 1 65 2/71 THE CLAIMS DEFINING TIIE INVENTION ARE AS FOLLOWS:-

   i. A control valve of the kind set forth in which the lost-motion connection comprises a first fixed abutment in the housing, a second abutment on the armature, engagement of the abutments limiting the movement of the armature relative to the push-rod assembly in the direction of the seating, the abutments being free to remain in engagement, and a stop limiting movement of the push-rod assembly towards the seating, the arrangement being such that in closing the valve, the push-rod assembly is stopped before the abutments engage.
2. 2. A control valve as claimed in Claim 1 in which the push-rod assembly carries a radial plate forming an abutment for one end of the pre-loaded spring of which the other end is in engagement with the first abutment at the end of the housing adjacent to the solenoid whereby the pre-loaded spring acts in a direction to urge the valve member into engagement with the valve seating.
3. 3. A control valve as claimed in Claim 1 or Claim 2 in which the housing is provided on the side of the valve seating remote from the valve member with an inlet connection, and the housing is provided on the opposite side of the valve seating with an outlet connection and a supply and return connection, a second valve seating being located between the outlet connection and the supply and return connection and the valve member being adapted to engage alternatively with the valve seatings, the outlet connection being in communication with the supply and return connection when the valve member is in engagement with the first valve seating, and the inlet connection being in communication with the outlet connection when the valve member is in engagement with the second valve seating.

   427407 No. 24,652/71 Proposed

   24, 65 2 71 4. A control valve as claimed in Claim 3 in which the supply and return connection incorporates a restriction to regulate the flow of hydraulic fluid therethrough.

   A control valve as claimed in Claim 4, in which the restriction comprises an orifice in a plate removably mounted in a passage in the housing in connection with and of a diameter greater than, a port defining the supply and return connection, and the plate is clamped between the inner end of a union screwed into the passage and a shoulder at a step in diameter between the passage and the port.

   6. A control valve as claimed in Claim 5, in which at least the edge of the plate which defines the end of the orifice facing away from the port is of a sharp substantially 900 outline.

   7. An hydraulic braking system incorporating a control valve as claimed in Claim 3, in which the inlet connection is connected to a source of high pressure fluid, the outlet connection is connected to an actuator for controlling the pressure of hydraulic fluid supplied to at least one wheel brake, and the supply and return connection is connected to a reservoir for supplying fluid to the high pressure source, a restriction being located in a line providing a connection between the supply and return.connection and the reservoir.

   8. An hydraulic braking system as claimed in Claim 7, in which the restriction comprises an orifice in a plate mounted in the line between the supply and return connection and the reservoir.

   9. An hydraulic braking system as claimed in Claim 8, inwhich the plate is removable mounted in a

   4274 07 .11. No. 24,652/71 Proposed 2.8.72

   24, 65.2/71 passage in the housing in communication with, and of a

   diameter greater than, a port in the housing of the

   control valve which defines the supply and return

   connection, and the plate is clamped between the inner

   end of a union screwed into the passage and a step

   in diameter between the passage and the port.

   An hydraulic braking system as claimed in

   Claim 9, in which the plate is interchangeable with a

   series of similar plates having orifices of different

   diameters, whereby the characteristics of wheel brake

   re-application can be varied.

   11. A control valve substantially as described

   with reference to and as illustrated in the accompanying

   drawings.

   12. An hydraulic braking system incorporating

   a control valve substantially as described with

   reference to and as illustrated in the accompanying

   drawings.

   DATED THIS Ist DAY OF August 1972.

   GIRLING LIMITED By its Patent Attorneys: CLEMENT HACK CO. Fellows Institute of Patent Attorneys of Australia.

   t 12 427407

   2 J,652 17.1
4. 4 27 407