GB1592459A - Control valve assemblies - Google Patents

Control valve assemblies Download PDF

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Publication number
GB1592459A
GB1592459A GB158877A GB158877A GB1592459A GB 1592459 A GB1592459 A GB 1592459A GB 158877 A GB158877 A GB 158877A GB 158877 A GB158877 A GB 158877A GB 1592459 A GB1592459 A GB 1592459A
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GB
United Kingdom
Prior art keywords
lever
control valve
force
input
valve assembly
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB158877A
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Girling Ltd
Original Assignee
Girling Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Girling Ltd filed Critical Girling Ltd
Priority to GB158877A priority Critical patent/GB1592459A/en
Publication of GB1592459A publication Critical patent/GB1592459A/en
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/26—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force characterised by producing differential braking between front and rear wheels
    • B60T8/30—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force characterised by producing differential braking between front and rear wheels responsive to load
    • B60T8/306—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force characterised by producing differential braking between front and rear wheels responsive to load using hydraulic valves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/18—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to vehicle weight or load, e.g. load distribution
    • B60T8/1812—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to vehicle weight or load, e.g. load distribution characterised by the means for pressure reduction
    • B60T8/1818—Lever mechanism

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Hydraulic Control Valves For Brake Systems (AREA)

Description

(54) IMPROVEMENTS IN OR RELATING TO CONTROL VALVE ASSEMBLIES (71) We, GIRLING LIMITED, a British Company, of Kings Road, Tyseley, Birmingham 11, 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: This invention relates to control valve assemblis for use in vehicle braking systems.
Control valves are usually positioned in the brake pressure line between the master cylinder and the rear wheel brakes to reduce or limit the pressure applied to the rear brakes relative to the full pressure applied to the front brakes. The valve may have a valve member which is subjected to a load in dependence upon vehicle loading so that the "cut-in" point of the valve, i.e. the inlet pressure at which the valve operates, is varied in dependence upon the vehicle loading.
In a previously proposed control valve assembly the load is applied by a torision spring having one end acting on the valve member and the other end connected to the rear axle. The spring is subjected to vehicle deflections and has a spring rate determined by the loads required to operate the control valve in both the laden and the part-laden cases. In certain cases that travel of the rear axle which corresponds to the total valvecontrolling spring travel is only a part of the total actual travel of the rear axle. For example the valve-controlling portion may only be as much as one third of the total rear axle travel.The resultant "over-travel" of the control spring can produce extremely high loads applied to the control valve member, and a control spring of far greater dimension and rate than is necessary to operate the valve would be required to cope with the over-travel conditions.
In accordance with the invention, there is provided a control valve assembly for a vehicle braking system, comprising a control valve having a valve member movable to control communication between an inlet and an outlet, and loading means for applying a load to the valve member, wherein said loading means comprises a lever arrangement including two levers directly pivoted together and arranged in series in forcetransmitting relationship with each other, and a force-applying means which is arranged to apply a substantially instant input force to one of the levers, the other lever applying an output force to the valve member, and wherein the lever ratio of said lever arrangement is variable in dependence upon vehicle loading, variations in said lever ratio varying the load on the control valve member.
Preferably, the lever ratio of said one lever is variable in dependence upon vehicle loading to vary the lever ratio of the lever arrangement. To vary the lever ratio of said one lever the point of application of the input force is preferably variable in dependence upon the vehicle loading.
A control valve assembly in accordance with the invention and a modification thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of the control valve assembly with the side part of the housing removed and showing a control valve in section.
Figure 2 is an end view of the valve assembly of Figure 1, and Figure 3 is an isometric view of a slightly modified control valve assembly with the housing completely removed and the control valves omitted for clarity.
The control valve assembly is usually mounted in use upon a sprung part of the vehicle and comprises two parallel control valves 1, which may be of any suitable form.
The valve illustrated in Figure 1 is a pressure reducing valve comprising a valve seat 2 fast with a movable differential valve member 3 and engageable with a spring biased ball valve closure member 4. A variable load is applied to the valve member 3, as will be described below, and when the pressure forces acting on the valve member are sufficient to overcome the variable load, the valve member moves to the left and the valve closes to shut off communication between the inlet chamber 5 and the outlet chamber 6. When the inlet pressure increases sufficiently the valve re-opens, and so on, the effect being to meter the pressure fluid passed to the outlet chamber 6, which is usually connected to the rear wheel brakes, as compared to the full pressure at the inlet, which is usually the front wheel braking pressure.
The arrangement for loading the valve member 3 comprises a pre-loaded spring 7 which engages at one end a seat 8 secured to an input member 9. An arm 10 (Figure 3) connects the input member 9 to the rear axle. Thus, the input member 9 is rotatable about its axis A (Figure 1) in dependence upon vehicle loading. The other end of the spring 7 engages a carrier 11 for a roller 12 which is biased by the spring 7 into engagement with a curved portion 13 of an input lever 14.
The input lever 14 is pivotally mounted on a pin 15 fixed in the housing 16 and is in force-transmitting relationship with a bifurcated output lever 17, the levers being arranged in series. In the valve assembly shown in Figure 1, the force-transmitting relationship is achieved by means of pinpoint connection 18 between the levers. In the modified assembly shown in Figure 3, the relationship is achieved by the engagement of opposed projections 19. formed on the input lever 1 , with the lower edges of the output lever 17. The output lever 17 pivotally engages a pin 20. A balance member 22 extends between and engages the valve member 3 of each valve and engages at its centre the end of the output lever 17 remote from the connection with the input lever 14.
In the assembly of Figures 1 and 2 stop 23 is provided to prevent overtravel of the input lever 14. Also, the position of the pin 20 is adjustable by an adjusting screw 21 to adjust the valves.
In operation a force which is dependent upon the input force of the spring 7 and the lever ratio of the input lever ]4 is transmitted by that lever to the output lever 17 which, in turn, applies a force dependent upon its lever ratio to the valve members 3.
The lever ratio of the input lever 14 is variable in dependence upon vehicle loading by rotation of the input member 9 which moves the roller 12 to vary the point of application of the spring force to the input lever 14. In the extreme position of the roller 12 illustrated in Figure 1 the line of application of the spring force 7 is substantially aligned with the pivot pin 15 so that substantially no force is transmitted to the output lever 17.
In the other extreme position shown in Figure 3, a maximum force is transmitted. The curved portion 13 of the input lever 14 is preferably arcuate and preferably has its centre on the axis A of input member 9 so that the length of the spring 7, and thus the spring rate and spring force. are constant irrespective of the position of the roller 12 and of the vehicle loading. However, the arc centre may be offset from the axis A so that, depending on which side of axis A the arc centre is, the roller will be automatically biased to either the fully loaded or the unloaded position if the arm 10 should fail.
The choice of position of the roller in the failed case will depend on particular vehicle braking requirements.
It will be appreciated that the total lever ratio is controllable so that there is no danger of extremely high loads being applied to the valve members 3 which might damage the control valves. Furthermore, the use of two levers in series can provide a larger total lever ratio than can a single lever of similar overall size.
Although described with two control valves, the loading arrangement could be used with only one such valve. The control valve or valves may be pressure reducing valves or pressure limiting valves of any suitable form.
Many other modifications are possible; for example the balance member 2 could be integral with the lever.
WHAT WE CLAIM IS: 1. A control valve assembly for a vehicle braking system, comprising a control valve having a valve member movable to control communication between an inlet and an outlet, and loading means for applying a load to the valve member, wherein said loading means comprises a lever arrangement including two levers directly pivoted together and arranged in series in forcetransmitting relationship with each other, and a force-applying means which is arranged to apply a substantially constant input force to one of the levers, the other lever applying an output force to the valve member. and wherein the lever ratio of said lever arrangement is variable in dependence upon vehicle loading, variations in said lever ratio varying the load on the control valve member.
2. A control valve assembly according to claim 1, including a stop which limits movement of the lever arrangement in the event of failure of the force-applying means.
3. A control valve assembly according to claim 1 or 2. wherein the lever ratio of said one lever is variable in dependence upon vehicle loading to vary the lever ratio of the lever arrangement.
4. A control valve assembly according to claim 3, wherein the point of application of the input force to said one lever is variable in dependence upon vehicle loading to vary the lever ratio of said one lever.
5. A control valve assembly according to claim 4, wherein the force-applying
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (15)

**WARNING** start of CLMS field may overlap end of DESC **. chamber 6. When the inlet pressure increases sufficiently the valve re-opens, and so on, the effect being to meter the pressure fluid passed to the outlet chamber 6, which is usually connected to the rear wheel brakes, as compared to the full pressure at the inlet, which is usually the front wheel braking pressure. The arrangement for loading the valve member 3 comprises a pre-loaded spring 7 which engages at one end a seat 8 secured to an input member 9. An arm 10 (Figure 3) connects the input member 9 to the rear axle. Thus, the input member 9 is rotatable about its axis A (Figure 1) in dependence upon vehicle loading. The other end of the spring 7 engages a carrier 11 for a roller 12 which is biased by the spring 7 into engagement with a curved portion 13 of an input lever 14. The input lever 14 is pivotally mounted on a pin 15 fixed in the housing 16 and is in force-transmitting relationship with a bifurcated output lever 17, the levers being arranged in series. In the valve assembly shown in Figure 1, the force-transmitting relationship is achieved by means of pinpoint connection 18 between the levers. In the modified assembly shown in Figure 3, the relationship is achieved by the engagement of opposed projections 19. formed on the input lever 1 , with the lower edges of the output lever 17. The output lever 17 pivotally engages a pin 20. A balance member 22 extends between and engages the valve member 3 of each valve and engages at its centre the end of the output lever 17 remote from the connection with the input lever 14. In the assembly of Figures 1 and 2 stop 23 is provided to prevent overtravel of the input lever 14. Also, the position of the pin 20 is adjustable by an adjusting screw 21 to adjust the valves. In operation a force which is dependent upon the input force of the spring 7 and the lever ratio of the input lever ]4 is transmitted by that lever to the output lever 17 which, in turn, applies a force dependent upon its lever ratio to the valve members 3. The lever ratio of the input lever 14 is variable in dependence upon vehicle loading by rotation of the input member 9 which moves the roller 12 to vary the point of application of the spring force to the input lever 14. In the extreme position of the roller 12 illustrated in Figure 1 the line of application of the spring force 7 is substantially aligned with the pivot pin 15 so that substantially no force is transmitted to the output lever 17. In the other extreme position shown in Figure 3, a maximum force is transmitted. The curved portion 13 of the input lever 14 is preferably arcuate and preferably has its centre on the axis A of input member 9 so that the length of the spring 7, and thus the spring rate and spring force. are constant irrespective of the position of the roller 12 and of the vehicle loading. However, the arc centre may be offset from the axis A so that, depending on which side of axis A the arc centre is, the roller will be automatically biased to either the fully loaded or the unloaded position if the arm 10 should fail. The choice of position of the roller in the failed case will depend on particular vehicle braking requirements. It will be appreciated that the total lever ratio is controllable so that there is no danger of extremely high loads being applied to the valve members 3 which might damage the control valves. Furthermore, the use of two levers in series can provide a larger total lever ratio than can a single lever of similar overall size. Although described with two control valves, the loading arrangement could be used with only one such valve. The control valve or valves may be pressure reducing valves or pressure limiting valves of any suitable form. Many other modifications are possible; for example the balance member 2 could be integral with the lever. WHAT WE CLAIM IS:
1. A control valve assembly for a vehicle braking system, comprising a control valve having a valve member movable to control communication between an inlet and an outlet, and loading means for applying a load to the valve member, wherein said loading means comprises a lever arrangement including two levers directly pivoted together and arranged in series in forcetransmitting relationship with each other, and a force-applying means which is arranged to apply a substantially constant input force to one of the levers, the other lever applying an output force to the valve member. and wherein the lever ratio of said lever arrangement is variable in dependence upon vehicle loading, variations in said lever ratio varying the load on the control valve member.
2. A control valve assembly according to claim 1, including a stop which limits movement of the lever arrangement in the event of failure of the force-applying means.
3. A control valve assembly according to claim 1 or 2. wherein the lever ratio of said one lever is variable in dependence upon vehicle loading to vary the lever ratio of the lever arrangement.
4. A control valve assembly according to claim 3, wherein the point of application of the input force to said one lever is variable in dependence upon vehicle loading to vary the lever ratio of said one lever.
5. A control valve assembly according to claim 4, wherein the force-applying
means comprises an arm pivotable about a pivot axis and engaging the said one lever, the point of engagement being dependent upon the position of the arm relative to its pivot axis.
6. A control valve assembly according to claim 5, wherein the said one lever has an arcuate portion, said arm engaging the arcuate portion and being movable therealong.
7. A control valve assembly according to claim 6, wherein the arcuate portion is an arm of a circle and has its axis coincident with the pivot axis of the arm.
8. A control valve assembly according to claim 6, wherein the arcuate portion is an arc of a circle and has its axis offset from the pivot axis of the arm.
9. A control valve assembly according to any of claims 5 to 8, wherein in one extreme position of the arm the longitudinal axis of the arm is substantially in alignment with a fixed pivot about which the said one lever is pivotable.
10. A control valve assembly according to any of claims 1 to 9, wherein the input force is applied by resilient means.
11. A control valve assembly according to claim 10 as appendant to any of claims 5 to 9, wherein the resilient means is a component part of said arms.
12. A control valve assembly according to claim 10 or 11, wherein the resilient means is a coil compression spring.
13. A control valve assembly according to any of claims 1 to 12, wherein the loading means acts on two said control valves arranged parallel to each other.
14. A control valve assembly constructed and arranged substantially as herein described with reference to Figures 1 and 2 or Figure 3 of the accompanying drawings.
15. A vehicle braking system incorporating a control valve assembly according to any preceding claim.
GB158877A 1978-01-12 1978-01-12 Control valve assemblies Expired GB1592459A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB158877A GB1592459A (en) 1978-01-12 1978-01-12 Control valve assemblies

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB158877A GB1592459A (en) 1978-01-12 1978-01-12 Control valve assemblies

Publications (1)

Publication Number Publication Date
GB1592459A true GB1592459A (en) 1981-07-08

Family

ID=9724551

Family Applications (1)

Application Number Title Priority Date Filing Date
GB158877A Expired GB1592459A (en) 1978-01-12 1978-01-12 Control valve assemblies

Country Status (1)

Country Link
GB (1) GB1592459A (en)

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PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee