HYDRAULIC POWER STEERING SYSTEM

• US 20130268161A1
• Filed: 04/03/2013
• Published: 10/10/2013
• Est. Priority Date: 04/10/2012
• Status: Active Grant

• Current Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Original Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Inventors: IZUTANI, Keisuke
• Granted Patent: US 9,079,609 B2
• Time in Patent Office: Days
• US Class Current: 701/42
• CPC Class Codes: B62D 5/065 characterised by specially adapted means for varying pressurised fluid supply based on need, e.g. on-demand, variable assist
• CPC Class Codes: B62D 5/09 characterised by means for actuating valves
• CPC Class Codes: B62D 5/091 Hydraulic steer-by-wire systems, e.g. the valve being actuated by an electric motor

Abstract

A first valve opening degree correction value computation unit computes a correction value (first valve opening degree correction value) for the absolute value of a valve opening degree command value on the basis of a rotation speed deviation computed by a rotation speed deviation computation unit in a pump driving motor control unit. A second valve opening degree computation unit computes a correction value (second valve opening degree correction value) for the valve opening degree command value on the basis of the sign of the valve opening degree command value and the first valve opening degree correction value. A correction value addition unit adds the second valve opening degree correction value to the valve opening degree command value set by the valve opening degree command value setting unit.

Claims

1. A hydraulic power steering system that generates a steering assist force by supplying hydraulic fluid from a hydraulic pump to a power cylinder, which is coupled to a steering mechanism of a vehicle, via a hydraulic control valve that is not mechanically coupled to a steering member, comprising:

a pump driving motor that is used to drive the hydraulic pump;

a valve driving motor that is used to control an opening degree of the hydraulic control valve;

rotation speed detection means for detecting a rotation speed of the pump driving motor;

rotation speed command value setting means for setting a rotation speed command value that is a command value of the rotation speed of the pump driving motor;

pump driving motor drive control means for executing drive control on the pump driving motor such that the rotation speed detected by the rotation speed detection means is equal to the rotation speed command value set by the rotation speed command value setting means;

opening degree command value setting means for setting an opening degree command value that is a command value of the opening degree of the hydraulic control valve;

opening degree command value correction means for correcting the opening degree command value, which is set by the opening degree command value setting means, on the basis of a deviation between the rotation speed command value set by the rotation speed command value setting means and the rotation speed detected by the rotation speed detection means; and

valve driving motor drive control means for executing drive control on the valve driving motor on the basis of the opening degree command value obtained through correction by the opening degree command value correction means.

2. The hydraulic power steering system according to claim I, wherein

the opening degree command value correction means includes:

opening degree command value correction means for correcting the opening degree command value set by the opening degree command value setting means such that the steering assist force increases when the rotation speed detected by the rotation speed detection means is lower than the rotation speed command value set by the rotation speed command value setting means; and

opening degree command value correction means for correcting the opening degree command value set by the opening degree command value setting means such that the steering assist force decreases when the rotation speed detected by the rotation speed detection means is higher than the rotation speed command value set by the rotation speed command value setting means.