Toyota Jidosha Kabushiki Kaisha

Akihiro Ohtomo

Akira Sakai

Fumiaki Kawahata

Hirohiko Morikawa

Kiyoharu Nakamura

Masayasu Ohkubo

Amane Shimura

Masaharu Yamashita

Kenichiro Aoki

Eiji Kasai

Keitaro Niki

Masaki Fujimoto

Tsutomu Onagi

Megumu Nishikohri

An electric power steering device for a vehicle includes an estimation mechanism estimating if there is a possibility that a backward electric current flows in a booster circuit toward a vehicle battery device, and a boosting controller stopping the boosting operation of the booster circuit to prevent a backward electric current from flowing in the booster circuit when it is estimated that there is a possibility that a backward electric current flows by the estimation mechanism. The estimation mechanism estimates that there is a possibility that a backward electric current flows in the booster circuit when the steering condition of a steering wheel is a returning condition or a steering-held condition. Otherwise, the estimation mechanism estimates if a backward electric current flows on the basis of input and output voltages of the booster circuit and information on the switching of a first boosting switching element. Thereby, overheat of the booster circuit can be prevented.

Electric power steering device

In a brake fluid control device, front wheel cylinders are connected to a front hydraulic circuit, and rear wheel cylinders are connected to a rear hydraulic circuit. The front hydraulic circuit and the rear hydraulic circuit are connected to a front left pressure-decrease valve, a front right pressure-decrease valve, a rear left pressure-decrease valve, a rear right pressure-decrease valve and a connecting pipe. When a brake pedal is depressed, the front left pressure-decrease valve, the front right pressure-decrease valve, the rear left pressure-decrease valve and the rear right pressure-decrease valve are opened and a master cylinder pressure sensor leads to both the front hydraulic circuit and the rear hydraulic circuit. Comparing a detection value of the of the master cylinder pressure sensor, a detection value of a front wheel cylinder pressure sensor and a detection value of a rear wheel cylinder pressure sensor respectively, detects the state of operation of each of the sensors provided in the system.

Brake fluid pressure control device

A brake fluid pressure control apparatus achieves a sufficiently large brake force even when a malfunction occurs in an operational force sensor for detecting a level of operational force applied to a brake system. A magnitude of a master cylinder pressure generated by a master cylinder is detected by a master cylinder pressure sensor. A linear fluid pressure source generates a linear fluid pressure adjusted by the magnitude of the master cylinder pressure. Front wheel cylinders and rear wheel cylinders are provided with the linear fluid pressure. A front wheel cylinder pressure is detected and a front wheel cylinder pressure value corresponding to a magnitude of the front wheel cylinder pressure is output by a front wheel cylinder sensor. If it is determined that a malfunction is occurring in the operational force sensor, a connection of the front wheel cylinders is switched from the linear fluid pressure source to the master cylinder. At this time, the linear fluid pressure source is controlled based on the front wheel cylinder pressure value.

Brake fluid pressure control apparatus for compensating a malfunction of

A hydraulic brake control apparatus in which a master cylinder supplies a brake fluid pressure responsive to a brake operating force to wheel cylinders through a first valve, includes a first control unit which controls second valves and third valves when a brake fluid pressure supplied to the wheel cylinders by a pressure supplying device is detected to be excessively high under a condition in which the supply of the brake fluid pressure to the wheel cylinders by the master cylinder is inhibited by the first valve, so that the supply of the brake fluid pressure to the wheel cylinders by the pressure supplying device is inhibited by the second valves and a flow of the brake fluid from the wheel cylinders into a reservoir tank is allowed by the third valves. A second control unit controls the third valves and the first valve at a predetermined time after the flow of the brake fluid from the wheel cylinders into the reservoir tank is allowed, so that the flow of the brake fluid from the wheel cylinders into the reservoir tank is inhibited by the third valves and the supply of the brake fluid pressure to the wheel cylinders by the master cylinder is allowed by the first valve.

Hydraulic brake control apparatus

A hydraulic brake control apparatus includes a pressure supply inhibiting unit which inhibits supply of a brake fluid pressure to wheel cylinders by a first pressure supplying unit when a defect in a brake fluid path between a first flow control unit and the wheel cylinders has occurred, and inhibits supply of a brake fluid pressure to the wheel cylinders by a second pressure supplying unit when a defect in a brake fluid path between a second flow control unit and the wheel cylinders has occurred. A pressure supply path control unit controls the first and second flow control units when a defect in one of a first brake fluid path between the first pressure supplying unit and the first flow control unit and a second brake fluid path between the second pressure supplying unit and the second flow control unit has occurred, such that a flow of the brake fluid from one of the first and second pressure supplying units connected to the defective path, into the wheel cylinders is inhibited, and a flow of the brake fluid from the other of the first and second pressure supplying units connected to the other path, into the wheel cylinders is allowed to supply the brake fluid pressure from the other pressure supplying unit to the wheel cylinders through the other path.

A hydraulic brake control apparatus in which a master cylinder is connected to wheel cylinders via a master cylinder cut valve, and the wheel cylinders are connected to a reservoir tank via a switching valve, includes a check valve provided between the master cylinder and the wheel cylinders in parallel with the master cylinder cut valve, the check valve provided in a bypass passage of the master cylinder cut valve, the check valve allowing a flow of a brake fluid from the master cylinder to the wheel cylinders and inhibiting a flow of the brake fluid from the wheel cylinders to the master cylinder. A valve control unit controls the switching valve when it is detected that a closed-position defect in the master cylinder cut valve has occurred and a pressure of the brake fluid in the master cylinder is decreasing, so that the switching valve is set at an open position to allow a flow of the brake fluid from the wheel cylinders to the reservoir tank through the switching valve and reduce a pressure of the brake fluid in the wheel cylinders.

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Toyota, Japan

Akihiro Ohtomo