Fluid handling – Systems – Supply and exhaust
Patent
1985-03-15
1986-06-10
Michalsky, Gerald A.
Fluid handling
Systems
Supply and exhaust
91372, 91375A, 91434, 91465, F15B 1302
Patent
active
045937184
DESCRIPTION:
BRIEF SUMMARY
This invention is cross-referenced to the application of the same inventors, Armin Lang and Helmut Knodler, Ser. No. 713,406, filed Mar. 15, 1985 and owned by the same Assignee.
BACKGROUND OF THE INVENTION
It has heretofor been customary as shown in German Pat. No. 19 24 032 and Counterpart British Pat. No. 1,254,673 to utilize a fork shaped end of a steering spindle comprising valve actuator pins having their axes in a plane with the steering spindle axis. These actuator pins protrude into elongated bores in respective valve pistons snugly without play, sliding normal to the steering spindle. The surface of the actuator pins and the surfaces of respective bores, as the steering spindle is rotated, keeps shifting relative the steering spindle axis due to the fixed path of reciprocation of the piston valves relative to the arcuate motion of the actuator pins. During this point of force shifting the valve pistons have about a 20% traverse. Thus, there is friction between the engaged surfaces. In order to avoid valve hysteresis it is necessary to keep the force needed to reciprocate the piston valves as small as possible.
BRIEF DESCRIPTION OF THE INVENTION
The invention is constructed to minimize friction and play by utilizing a geometry of steering spindle axis and the axes of the actuator pins such that they are not in the same plane. Thus, the latter axes are offset so that the points of force engagement between the surfaces of the valve piston bores and the respective actuator pins are in a plane with the steering spindle axis. This reduces the relative movement between the actuator pins and the valve pistons by a factor of 10. Such relative movement becomes so small that spring means may be utilized to effect motivation to dispense with positive drive in the opposite direction.
Further, the construction is adapted for increasing the lever arm length between the rotating steering spindle and the actuator pins so that for the same angular movement of the steering spindle a greater swing of the actuator pins results in a greater traverse of the valve pistons. This results in a lessening of friction between the actuator pins and the valve pistons since the driving forces are lessened. Such increase in lever arm is effected by providing a semi-bore or groove, open at the outside of each valve piston for the actuator pins.
Additionally, the novel construction has an advantage of permitting tolerance increase in production, as well as effecting an economy of manufacture as compared with providing full bores for the actuator pins.
A detailed desciption of the invention now follows in conjunction with the appended drawing, in which:
FIG. 1 is an embodiment shown in longitudinal cross section and
FIG. 2 is a second embodiment shown in longitudinal cross section.
Referring to FIG. 1, a valve body 1 is shown which will be understood to be at the terminal of a steering worm (not shown) and which is mounted rotatively in a booster steering housing 2 in a conventional manner. It will be understood that the steering worm connects with a steering spindle (not shown) in a conventional manner resiliently coaxial with a torsion rod 3. It will be further understood that the steering spindle has spaced arms of a fork shaped end which carries actuator pins 4 and 5 to actuate valve pistons 6 and 7 of respective control valves 8 and 9 transversely disposed to the longitudinal axis of the spindle. However, it will be noted that the axes of the pins are nonplanar to the axis of the spindle, although aligned in a symmetrical arrangement therewith, offset eccentrically as shown.
Each control valve 8 and 9 has a respective inlet annular groove 10 and 11 connecting with an inlet chamber 12 in the steering housing. Also, each control valve 8 and 9 has a respective return annular groove 13 and 14 and an annular groove 15 and 16 for connection with a tank (not shown) and for connection with respective pressure chambers 17 and 18 of a servo motor 19.
The valve pistons 6 and 7 are provided with transverse bores 20 and 21 shown to be
Knodler Helmut
Lang Armin
Michalsky Gerald A.
Zahnradfabrik Friedrichshafen AG
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