Load and speed dependent gear change hydraulic pressure generator
AssigneeRobert Bosch GmbH
InventorGerhard Will
Life of this patent
Estimating the term…
Abstract
A pump, driven by the engine, supplies hydraulic pressure as a function of engine speed; the engine controller provides a displacement force, for example by a cam, acting on a main valve slider, or spool of the switching pressure controller. To additionally provide a speed signal to the main spool, the switching pressure line, connected to the pump, has a Venturi, diaphragm, bent tube, or other constriction therein from which a hydraulic signal representative of engine speed can be derived, which hydraulic signal is applied as a force additionally acting on the main valve slider or spool so that the spool position, and hence output switching pressure, will be representative both of engine controller position as well as of engine speed.
Claims3
Apparatus supplying a gear changing or switching pressure, for use in vehicle transmissions, comprising:
- a pump (40) driven by the engine of the vehicle with a speed representative of engine speed, and a switching pressure line (33) connected to the pump and having arising therein a fluid switching pressure proportional to engine speed;
- a pressure controller (10) having a main valve slider (12), and feedback means (35, 14, 16) connected thereto and controlling the switching pressure;
- displaceable means (21, 28, 23, 37) changing position as a function of the change of position of the controller for the engine which controls engine speed and providing a force acting on the main valve slider (12) of the pressure controller, representative of engine controller position,
- the improvement comprising:
- a Venturi (41) located in the switching pressure line;
- and
- a control pressure line (38) branched off the throat of the Venturi to provide a pressure signal representative of flow of pressure fluid at the control pressure through the constriction;
- said control pressure line (38) and the displaceable means (21, 28, 23, 24, 37) providing a force representative of engine controller position acting on the main valve slider (12) such that the force representative of the control pressure and the force representative of engine controller position are applied to the main valve slider (12) in additive relation to change the position of the main valve slider as a function of the sum of said forces.
Dependencies are inferred from the claim text.