VARIABLE RATIO PROPORTIONING DEVICE

• US 3,741,610 A
• Filed: 07/13/1970
• Issued: 06/26/1973
• Est. Priority Date: 07/13/1970
• Status: Expired due to Term

• Current Assignee: Harvison C. Holland
• Original Assignee: Harvison C. Holland
• Inventors: Holland, Harvison C.
• Primary Examiner(s): Reger, Duane A.
• Application Number:
  US05/054,206
• Time in Patent Office: 1,079 Days
• Field of Search: 303/6A,6C,13,24C,24F,28,40,57,61,86,21CG,24A
• US Class Current: 303/9.67
• CPC Class Codes: B60T 11/34 Pressure reducing or limiting valves for arrangements for adjusting wheel-braking force responsive to vehicle weight or load B60T8/1831
• CPC Class Codes: B60T 8/26 characterised by producing differential braking between front and rear wheels using electrical circuitry or regulation means B60T8/17

Abstract

A proportioning device for producing a modulated outlet pressure which varies as a predetermined non-linear function of inlet pressure. A pair of opposed pistons are subjected to inlet and outlet pressures respectively and actuate a two-way valve for admitting pressure fluid to the outlet and permitting its return to the inlet. The forces on the pistons include pressure forces and also a biasing force whose value is determined by a third piston subjected to inlet pressure acting on the opposed pistons through a system of levers, a cam, and a spring.

Claims

1. A variable ratio proportioning device comprising in combination:

a housing containing a piston and cylinder connected to an inlet for pressure fluid on one side and to an outlet for pressure fluid on the other side;

means for applying a biasing force to the piston;

means for varying the magnitude of the biasing force as a predetermined, non-linear function of the inlet fluid pressure; and

means controlled by said piston for admitting fluid from the inlet to the outlet of the device and providing an outlet fluid pressure which varies according to said predetermined, nonlinear function of the inlet fluid pressure.

2. A variable ratio proportioning device comprising in combination:

a housing containing a first piston and cylinder connected to an inlet for pressure fluid, a second piston and cylinder connected to an outlet for pressure fluid, said pistons being oppositely disposed with inlet fluid pressure force on the first piston acting in opposition to the outlet fluid pressure force on the second piston;

means for applying a biasing force to the first piston modifying the inlet fluid pressure force acting thereon;

means for varying the magnitude of the biasing force as a non-linear function of the inlet fluid pressure;

valve means for admitting pressure fluid from the inlet to the outlet; and

means connecting the second piston to open the valve means when the fluid pressure force plus biasing force on the first piston exceeds the fluid pressure force on the second piston, so that the outlet pressure varies as a non-linear function of the inlet fluid pressure.

3. A device as defined in claim 2 in which the valve means consists of a ball check valve seating against an opening leading to the second cylinder, and the means for opening the valve means including a pin located in said opening for urging the ball from its seat, said pin being actuated by relative motion of the piston and the cylinder.

4. A device as defined in claim 2 in which the means for applying and varying a biasing force includes a baising spring, and a third piston and cylinder connected to the inlet, said third piston carrying a first pivoted lever arm connected at one end to the biasing spring and at the other end to connecting means for transferring said biasing force to the second piston.

5. A device as defined in claim 4 in which the connecting means includes a second pivoted lever arm contacting the first and second pistons and the first lever arm with one of said lever arms having a cam surface of predetermined profile at the contact point, whereby said contact point is shifted with respect to the pivots of the first and second lever arms according to displacement of the third piston to vary the biasing force according to the inlet fluid pressure force as modified by the interaction of the biasing spring and the cam profile.

6. A device as defined in claim 4 in which the end of the said biasing spring opposite the first lever arm is carried on an anchor in the housing, and including adjustment means for selectively adjusting the position of the anchor whereby the force of the biasing spring at any position of the said third piston may be varied for modifying the outlet fluid pressure characteristics of the device.

7. A device as defined in claim 6 in which the anchor consists of a bar retained in an elongate slot in a cylindrical portion of the housing, and the adjustment means includes a rotatable end cap receiving said bar in an elongate slot at an angle to the slot in the housing, said cap having calibrations whereby rotation of the cap is effective to adjust the position of the bar for varying the force of the biasing spring according to predetermined values.

8. For use on a vehicle having front and rear wheels and given tire adhesion and weight-transfer characteristics on braking, given vehicle loading, and front and rear fluid pressure operated brakes for braking the wheels, a proportioning device as defined in claim 1 in which the inlet is connected to the front brakes and the outlet is connected to the rear brakes, and in which the said means for varying the biasing force includes a cam and defines the non-linear function by which the outlet fluid pressure varies from the inlet fluid pressure, said cam having a profile which is predetermined according to the given tire adhesion, weight-transfer and front and rear brake mechanism characteristics of the vehicle.

9. For use on a vehicle having front and rear wheels and given tire adhesion and weight-transfer characteristics on braking, given vehicle loading, and front and rear fluid pressure operated brakes for braking the wheels, a proportioning device as defined in claim 6, in which the inlet receives fluid at a pressure varying as a function of front Brake pressure fluid, the outlet supplies pressure fluid to said rear brakes, and said piston, spring, cam lever and connecting means elements define the non-linear function by which the outlet fluid pressure varies from the inlet fluid pressure, said cam lever having a profile which is predetermined according to the given tire adhesion, weight-transfer and front and rear brake mechanism characteristics of the vehicle and said bias spring adjusting means being provided for further modifying outlet fluid pressure according to the given vehicle loading.

10. In a vehicle brake system having fluid pressure generating means, front and rear wheel brakes, and front and rear brake lines for transmitting fluid pressure to said front and rear wheel brakes respectively from said pressure generating means:

a pressure proportioning device connected in said rear brake line, said device including regulating means for regulating the fluid pressure transmitted through said rear brake line to said rear wheel brakes as a predetermined non-linear function of fluid pressure supplied from said fluid pressure generating means, said predetermined function representing tire adhesion, weight-transfer and front and rear wheel brake mechanism characteristics of the vehicle, said regulating means being operable to regulate the fluid pressure in said rear brake line so as to increase the ratio of front to rear braking effort upon increase in total braking force according to said predetermined function.

11. In a vehicle brake system having front and rear master cylinders, front and rear wheel brakes, and front and rear brake lines for transmitting fluid pressure to said front and rear wheel brakes respectively from said front and rear master cylinders:

a pressure proportioning device connected in said rear brake line, said device including regulating means for regulating the fluid pressure transmitted through said rear brake line to said rear wheel brakes as a predetermined non-linear function of fluid pressure supplied from said rear master cylinder, said predetermined function representing tire adhesion, weight-transfer and front and rear wheel brake mechanism characteristics of the vehicle, said regulating means being operable to regulate the fluid pressure transmitted to said rear brake line so as to increase the ratio of front to rear braking effort upon increase in total braking force according to said predetermined function.

12. In a vehicle brake system having front and rear master cylinders, front and rear wheel brakes, and front and rear brake lines for transmitting pressure fluid to said front and rear wheel brakes respectively from said front and rear master cylinders;

a pressure proportioning device including regulating means concurrently responsive to predetermined tire adhesion and weight-transfer characteristics of the vehicle and front and rear wheel brake mechanism characteristics of the vehicle, said regulating means being operable to regulate the fluid pressure in said rear brakes so as to increase the ratio of front to rear braking effort upon increase in total braking force as a function of said characteristics under normal operating condition, and means responsive to a loss in front brake line pressure for shifting said regulating means to pass substantially full rear brake line pressure to said rear wheel brakes.

13. In a proportioning device for regulating an outlet fluid pressure of the type comprising a housing having an inlet passage for receiving and returning a pressure fluid, the pressure of which is variable, an outlet passage for receiving and returning pressure fluid, a regulating check valve controlling fluid flow between the inlet passage and the outlet passage, and arranged to close against the flow to the outlet passage and permit flow by opening of the valve from the outlet to the inlet;

the improvement of a dual piston cooperating with the valve and having opposed reaction areas subjected to the fluid pressures in the inlet and outlet passages, and a varIable resilient biasing means constructed and arranged to react on the piston in opposition to the inlet fluid pressure, including a second single piston having a third control area, the movement of which controls the programming of a number of predetermined non-linear inlet to outlet fluid pressure relationships through the action of said biasing means.