GB1590688A - Non-return valve for incorporation in a nipple of a hydraulic system - Google Patents

Description

PATENT SPE(IFICATION

( 11) 1 590688 Application No 4520/80 ( 22) Filed 10 Aug 1977 ( 19) Divided Out of No 1 590 685 Convention Application No 771 383 ( 32) Filed 8 March 1977 in South Africa (ZA) ( 44) Complete Specificathi ( 51) INT CL 3 F 16 K lo ( 52) Index at acceptance F 2 V D 3 J 4 C in published 3 June 1981 5/02 ( 54) NON-RETURN VALVE FOR INCORPORATION IN A NIPPLE OF A HYDRAULIC SYSTEM ( 71) We, REVERSE INJECTION COMPANY (PROPRIETARY) LIMITED, a Company incorporated with limited liability in accordance with the laws of the Republic of South Africa, of Midmacor House, Booysens Road, Selby, Transvaal Province, Republic of South Africa, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following

statement: -

The present application is a divisional application out of our Application No.

33547/77, hereafter referred to as the parent application (Serial No 1,590,685).

This invention relates to the bleeding of an hydraulic system and to apparatus for use therewith It relates in particular to the bleeding of an hydraulic system which comprises a master cylinder and piston assembly, a slave cylinder and piston assembly, and an hydraulic line connecting the master cylinder to the slave cylinder for operatively conducting fluid between them.

The apparatus therefore finds particular use in bleeding the hydraulic brake systems of motor vehicles.

By the term 'bleeding' is to be understood the removal of air, dirt, or other contaminants from the hydraulic system, or charging, purging, or flushing the system with clear, uncontaminated hydraulic fluid, i e hydraulic fluid which is free of substances which can impair the proper operation of the system, e g dirt, air, or the like.

In conventional hydraulic brake systems known to the applicant, closable bleed openings are provided at high points in the systems, i e at the upper regions of the slave cylinders Closability is provided by screw-threaded bleed nipples adapted to screw into threw-threaded sockets to close off the bleed openings.

Bleeding of such systems takes place by opening the bleed opening, unscrewing the bleed nipple, and by pumping hydraulic fluid by means of the piston in the master cylinder, thereby expelling air from the slave cylinder, and of then closing the bleed opening by screwing the bleed nipple home.

A disadvantage of this system of bleeding is that one person is needed to operate the master piston to pump hydraulic fluid from the master cylinder through to the slave 55 cylinder, and another person is required to watch the bleed opening and to close it off as soon as air stops issuing from it The master cylinder then has to be charged again with hydraulic fluid to the appropriate 60 level Bleeding carried out in this fashion is often not fully effective, because it is not always possible to bleed all the air out of such systems in this fashion.

In the parent application a method of 65 bleeding an hydraulic system is described.

Such a method of bleeding an hydraulic system, which comprises a master cylinder and a piston assembly, a slave cylinder and piston assembly, an hydraulic line connect 70 ing the master cylinder to the slave cylinder for operatively conducting hydraulic fluid between the cylinders, and a master cylinder reservoir which is in fluid flow communication with the master cylinder, 75 includes the steps of withdrawing hydraulic fluid from the master cylinder reservoir; and of introducing hydraulic fluid into the system at the slave cylinder by hydraulic fluid supply means to cause flow of 80 hydraulic fluid from the slave cylinder and along the hydraulic line to the master cylinder The hydraulic fluid may be withdrawn from the reservoir of the master cylinder by hydraulic fluid suction means while main 85 taining the hydraulic fluid in the master cylinder reservoir at a predetermined level.

Liquid withdrawn from the master cvlinder may be introduced again at the slave cylinder 90 The volumetric flow rate capacity of the hydraulic fluid suction means may be about 12 to 2 litres per minute and may exceed that of the hydraulic fluid supply means by about 50 % 95 Our co-pending divisional application, 17323/78 (Serial No 1 590686) divided from the same parent application, describes and claims a nipple assembly comprising (a) a nipple formed in one piece and 100 ( 21) ( 62) ( 31) ( 33) CO\ L:1 1,590,688 having an inner end and an outer end, the inner end having a male screw thread adapted to screw into a screw-threaded socket of a hydraulic slave cylinder; a hydraulic fluid flow passage extending between the ends; and a seat between the ends around the passage to accommodate a replaceable nonreturn valve for a hydraulic fluid sealingly in the passage; and (b) a non-return valve in the form of a unitary assembly insertable into and removable from the nipple flow passage as a unit and retained sealingly seated in the seat; the non return valve incorporating a flow passage and means to permit flow therethrough in one direction only, the 'nonreturn valve being arranged to permit flow of hydraulic fluid under pressure from the outer end along the passage through the nipple to the inner end, but to prevent hydraulic flow in the reverse direction The seat may be frusto-conical.

According to this invention there is provided a non-return valve for such a nipple assembly, the non-return valve being in the form of a unitary assembly insertable into and removable from the nipple's flow passage as a unit, and having a valve body and resilient sealing member around the valve body, the resilient sealing member being adapted to seat sealingly in a seat in a nipple and being of a material which is resistant to attack by hydraulic fluid.

The non-return valve may comprise a valve body seating sealingly in the seat, and having a flow passage and a valve seat adapted to be in series with the nipple flow passage; and a closure member urged to seat on the seat of the valve body The closure member may include a resilient material which is resistant to attack by hydraulic fluid.

The non-retum valve may have a male screw thread on its valve body to co-operaate with a female screw thread in the flow passage of the nipple.

Apparatus for carrying out the method as described in the parent application, comprises hydraulic fluid suction means adapted for drawing hydraulic fluid from the master cylinder reservoir, and hydraulic fluid supply means adapted to supply hydraulic fluid under pressure to the slave cylinder.

There may further be provided an hydraulic connector for connecting the hydraulic fluid supply means to the slave cylinder, the hydraulic connector incorporating a valve closure member urged to the closed position, the said closure member being adapted to become unseated when the hydraulic connector engages with a nipple assembly as specified above, fitted to the slave cylinder.

The invention will now be described in more detail, by way of example, with reference to the accompanying drawings.

In the drawings Figure 1 shows diagrammatically a diagram of hydraulic fluid flow in a hydraulic 70 system being bled with the aid of a nipple assembly incorporating a non-return valve according to the invention; Figure 2 shows a side view of a transportable trolley incorporating a hydraulic con 75 nector engageable with such a nipple assembly; Figure 3 shows an axial section of a nipple assembly incorporating a non-return valve according to the invention; 80 Figure 4 shows an axial section of an hydraulic connector adapted to engage with the nipple assembly of Figure 5 shows diagrammatically a sectional elevation of a slave cylinder and 85 nipple assembly for a disc brake.

In Figure 1, reference numeral 10 generally indicates an apparatus having hydraulic fluid supply means and hydraulic fluid suction means in the form of pressure and 90 suction pumps for use in bleeding the hydraulic brake system of a motor vehicle.

Reference numeral 12 indicates part of a vehicle's brake system The brake system includes a master cylinder and piston 95 assembly 14, a brake pedal 16 for operating the piston 14 1 of the assembly 14, and a master cylinder reservoir 18 When the pedal is released, the reservoir 18 is in fluid flow communication with the cylinder 14 100 The reservoir has a filler opening 20.

The brake system further includes a brake slave cylinder and piston assembly 22 on each, isay, of the four wheels (only one of which is shown at 24) of the vehicle The 105 master cylinder of the master cylinder and piston assembly 14 is connected to the slave cylinder of the slave cylinder and piston assembly 22 by means of a connector 25 and an hydraulic line 26 110 The apparatus 10 is mounted in a trolley which can be moved around by hand (see Figure 2) It comprises hydraulic fluid supply means in the form of a delivery pump (not shown) The apparatus further 115 comprises hydraulic fluid suction means in the form of a peristalitic suction pump (not shown It has a suction conduit 42 for withdrawing hydraulic fluid from the master cylinder reservoir 18, and a delivery con 120 duit 45 4 for introducing hydraulic fluid into the slave cylinder 22 via a nipple assembly 21 The suction conduit 42 comprises a length of flexible tubing having at its end a suction connection in the form of a 125 hooked piece of rigid tubing 42 2 The suction conduit 42 incorporates a stop cock 46.

An opening 42 3 in the tubing 42 2 is arranged to lie at a certain level in the 1,590,688 master cylinder reservoir to maintain a certain level of fluid therein.

The apparatus 10 is provided with connections 45 3 to which flexible conduits 45 4 are connectable via connections 45 5 Each flexible conduit 45 4 also has a connection 45.6 for connection to a nipple assembly 21 of a slave cylinder 22 The connections 45 3 and 45 5 may each have valves incorporated in them so that when connections are made both valves become unseated This is to ensure that hydraulic fluid contained in the various conduits does not drain when the conduits are disconnected Likewise, the connections 45 6 and the nipple assemblies 21 have valves which are unseated when connection is made between a connection 45.6 and a nipple assembly 21 (See in this connection the description with reference to

Figures 3 and 4 of the drawings).

The slave cylinder 22 is provided with a nipple assembly 21 (see Figure 3) having a passage in which there is a non-return valve 186 permitting flow of hydraulic fluid into the slave cylinder Details of the nipple assembly 21 in accordance with 'the invention, are shown in Figure 3 of the drawings.

Referring to Figure 3 of the drawings, reference numeral 21 refers generally to a nipple assembly in accordance with the invention, having a bleed passage 21 1 It has a formation 180 for engagement by a spanner, a screw-threaded inner end 182 adapted to screw into a threaded socket in a slave cylinder It has a seat 184 adapted to engage sealingly with a non-return valve, generally indicated by reference numeral 186, engaging with the screw-threaded bore 188 in the outer end of the passage 21 1.

The non-return valve 186 is of substantially similar construction to that used for pneumatic tyres and tubes However, there is this difference in that the seal 186 1 of the non-return valve as well as the seat 186 2 of the valve, are of a resilient material which is resistant to attack by hydraulic fluid The nipple assembly 21 is provided further with an outer end (screw-threaded or with other suitable connection) 190 for engaging with the connection 45 6 of the flexible supply lines 45 4 The closure member 186 3 of the non-return valve 186 becomes unseated when the connection 45 6 engages with the screw thread 190 (see Figure 4) The non-return valve 186 has a passage extending longitudinally within the passage 21 1 of the nipple assembly 21 The closure member 186 3 has a stem lying in the said passage The outer end 186 31 of the stem projects beyond the passage of the non-return valve and lies within the outer end 190 of the nipple The closure member seat 186 2 is urged to seat on the inner end of the said passage of the non-return valve to close it off The valve closure member 45.61 abuts against the end 186 31 of the closure member 186 3, resulting in both closure members being unseated when the hydraulic connector 45 6 engages with a nipple assembly 21 A removable dust cap 70 192 engaging with the screw thread 190 is also provided.

In operation, for the bleeding of the hydraulic brake system of a vehicle, the trolley 150 is pushed so that it is near to 75 the vehicle Thereupon, four conduits 45 4 are connected via connectors 45 6 to the nipples assemblies of the various wheels.

There will therefore be four conduits 45 4 interconnecting the console 150 to the four 80 wheels of 'the vehicle Upon making the connections 45 6 and 21, the non-return valves built into the connection pieces, become unseated The passages in them are thereby placed in communication with 85 each other The flexible conduits 45 4 may form more or less a permanent part of the apparatus but may be disconnected at 45 5 from the connections 45 3.

Thereupon the piping 42 2 is inserted into 90 the reservoir 18 of the master cylinder 14.

The sleeve 42 4 is adjusted to a position to ensure that when hydraulic fluid is pumped into the system, it will be drawn off at a sufficient rate by the suction pump so that 95 the level will not rise above a reasonable level in the reservoir, e g at level 18 1 as indicated in Figure 1 of the drawings.

Thereupon the motors for the suction and pressure pumps are energised This causes 100 clean hydraulic fluid to be forced along the supply lines 45 4 and into the slave cylinder 22 Hydraulic fluid in the slave cylinder 22 thereby becomes displaced into the reservoir 18 of the master cylinder 14 However, 105 hydraulic fluid is also being withdrawn from the master cylinder via the tube 42 2, but the level of fluid in the master cylinder does not drop below the level 18 1 because of the position of the sleeve 42 2 over the 110 slot 42 3 in the tube 42 2 The capacity of the suction pump is greater than that of the supply pump, therefore the level of hydraulic fluid in the master cylinder will not rise above the level 18 1 and will there 115 fore not spill over at the master cylinder.

The method of bleeding as described in the parent application, can be carried out particularly successfully where the line leading from the slave cylinder to the master 120 cylinder is at a higher level than the level at which introduction of the hydraulic fluid into the slave cylinder takes place via the hydraulic connector 45 6 Reference is now made to Figure 5 in which there is shown a 125 slave cylinder assembly 220 in accordance with the invention.

This assembly comprises a pair of slave cylinders 222 and 224 interconnected via a channel 226 The cylinders have pistons 228 130 1,590,688 and 230 arranged on either side of a disc 232 In accordance with the conventional practice, the master cylinder hydraulic line connects with the cylinder 224 at about the line 224 1; and a bleed screw nipple is provided at the end of the branch passage 226 1 In accordance with the invention, however, (shown in Figure 5) the master cylinder hydraulic line connects with the branch passage 226 1 and nipple assemblies 21 in accordance with the invention are provided at a low level in each of the cylinders 222 and 224.

Hence, it is better to have the bleed nipple of a slave cylinder at a lower level rather than at a high level as has been the practice heretofore The slave cylinder connection leading to the master cylinder may be at a high level.

Attention is directed to our co-pending applications 33547/77 (Serial No 1,590,685) 223/80 (Serial No 1,590,687) and 17323/78 (Serial No 1,590,686) which respectively claim the method of bleeding described herein, the apparatus for carrying out that method, and the nipple assembly described herein.

Claims (6)

WHAT WE CLAIM IS:-

1 A non-return valve for hydraulic fluid adapted to be seated within a nipple having an inner end and an outer end, a hydraulic fluid flow passage extending between the ends, and a seat between the ends around the passage to accommodate the non-return valve sealingly in the passage; the non-return valve being in the form of a unitary assembly insertable into and removable from the nipple's said flow passage as a unit, and having a valve body and a resilient sealing member around the valve body the resilient sealing member being adapted to seat sealingly in the seat of the nipple and being of a material which is resistant to attack by hydraulic fluid.

2 A non-return valve according to claim 1 wherein the resilient sealing member is adapted to seat sealingly in a seat which is frusto-conical.

3 A non-return valve according to claim 1 or claim 2 comprising a valve body having a flow passage and a valve seat adapted to be in series with the nipple flow passage when the non-return valve is seated in the seat of the nipple; and a closure member urged to seat on the valve seat of the valve body, the closure member including a resilient material resistant to attack by hydraulic fluid.

4 A non-return valve according to claim 3 wherein the closure member is a stem passing along the non-return valve flow passage, the stem having an outer end projecting out of the non-return valve flow passage.

A non-return valve according to any one of the preceding claims having a male screw thread on the valve body to cooperate with a female screw thread in the flow passage of the nipple.

6 A non-return valve substantially as herein described with reference to Figure 3 of the accompanying drawings.

MEWBURN ELLIS & CO, Chartered Patent Agents, European Patent Attorneys, 70/72 Chancery Lane, London WC 2 A l AD.

Agents for the Applicants.

Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon), Ltd -1981.

Published at The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.