Fluid flow control apparatus for a power steering system
First Claim
1. An apparatus for controlling fluid flow from a hydraulic pump to a hydraulic power steering mechanism, said apparatus comprising:
- orifice means, through which fluid from the pump flows to the steering mechanism, for generating a hydraulic control signal proportional to the fluid flow rate through said orifice means;
flow control valve means for bypassing fluid flow away from the steering mechanism in response to said hydraulic control signal; and
control means for modifying said hydraulic control signal including a pilot fluid circuit between the pump and said orifice means and a solenoid operated valve means in said pilot fluid circuit and operable in response to a secondary control signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A power steering system includes a hydraulic pump and a hydraulic steering mechanism. A flow control orifice passes fluid from the pump to the steering mechanism and generates a hydraulic control signal proportional to the fluid flow rate therethrough. A flow control valve is connected between the pump to bypass fluid away from the steering mechanism in response to the hydraulic control signal. A solenoid operated valve is located in a pilot fluid circuit between the pump and the flow control orifice to vary the hydraulic control signal in response to an electrical control signal. The electrical control signal is a pulse width modulated signal having a duty cycle proportional to vehicle speed. Maximum power assist occurs when vehicle speed is below a predetermined value and decreases with increasing vehicle speed above the predetermined value.
29 Citations
8 Claims
-
1. An apparatus for controlling fluid flow from a hydraulic pump to a hydraulic power steering mechanism, said apparatus comprising:
-
orifice means, through which fluid from the pump flows to the steering mechanism, for generating a hydraulic control signal proportional to the fluid flow rate through said orifice means; flow control valve means for bypassing fluid flow away from the steering mechanism in response to said hydraulic control signal; and control means for modifying said hydraulic control signal including a pilot fluid circuit between the pump and said orifice means and a solenoid operated valve means in said pilot fluid circuit and operable in response to a secondary control signal. - View Dependent Claims (2, 3)
-
-
4. A vehicle power steering apparatus comprising:
-
a pump for providing hydraulic fluid under pressure; a hydraulic assist steering motor in communication with said pump for steering vehicle wheels; flow control orifice means for generating a hydraulic control signal proportional to the fluid flow rate between said pump and said steering motor; flow control valve means for bypassing fluid away from said steering motor in response to said hydraulic control signal; speed measuring means for measuring speed of the vehicle and for generating a signal indicative thereof; and control means for modifying said hydraulic control signal in response to said signal from said speed measuring means. - View Dependent Claims (5, 6)
-
-
7. A vehicle power steering apparatus comprising:
-
a pump for providing hydraulic fluid under pressure; a power steering mechanism operatively connected to a steering wheel of a vehicle and the steerable wheels of the vehicle; a main conduit connected to said pump and said power steering mechanism for communicating fluid from the pump to the power steering mechanism; flow control orifice means located in said main conduit for generating a hydraulic control signal in response to the fluid flow rate through said flow control orifice means; bypass valve means connected to the pump and to a reservoir for bypassing fluid in response to said hydraulic control signal; conduit means for communicating said hydraulic control signal to said bypass valve means; solenoid operated valve means operatively connected to said pump and to said conduit means for modifying said hydraulic control signal responsive to a solenoid control signal; and electronic control means for generating said solenoid control signal in response to a secondary control signal. - View Dependent Claims (8)
-
Specification