JP2013248986A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily avoid a risk in an emergency without causing steering delay.SOLUTION: A power steering device 1 includes a steering shaft 2, a power steering unit 3, an ECU 12, and a flow rate control device 5. The steering shaft 2 is connected to a steering wheel SW. The power steering unit 3 applies torque to the steering shaft 2 according to a flow rate of hydraulic oil to be supplied. The ECU 12 determines whether a vehicle is in a pre-collision state where the vehicle is highly likely to come into contact with an object located forward in an advancing direction. The flow rate control device 5 controls a flow rate of the hydraulic oil to be supplied to the power steering unit 3 so as to be maximized when the ECU 12 determines the pre-collision state.

Description

  The present invention relates to a power steering device mounted on a vehicle.

  Conventionally, steering assist by a power steering device (steering device) is performed by hydraulic pressure. In order to save fuel in passenger cars, power steering devices are becoming more and more electrified. However, in a commercial vehicle with a large axle load, it is difficult to perform steering assist only by electric power like a passenger car. Therefore, in a power steering apparatus that performs steering assist with hydraulic pressure, it has been proposed to reduce fuel consumption by changing the discharge flow rate of a hydraulic pump (see, for example, Patent Document 1).

JP 2007-92761 A

  However, since the steering assist force is reduced by reducing the flow rate, a sufficient assist force cannot be obtained when an emergency danger such as a collision is avoided, and a steering delay may occur.

  Accordingly, an object of the present invention is to provide a power steering device that can easily avoid danger in an emergency without causing a steering delay.

  In order to achieve the above object, the present invention is a power steering device mounted on a vehicle, and includes a steering shaft, a steering shaft drive means, a collision determination means, and a flow rate control means.

  The steering shaft is connected to the steering wheel. The steering shaft driving means applies torque to the steering shaft with a strength corresponding to the flow rate of the supplied hydraulic oil. The collision determination means determines whether or not the vehicle is in a pre-collision state where there is a high possibility that the vehicle will come into contact with an object that exists in front of the vehicle in the traveling direction. The flow rate control unit controls the flow rate of the hydraulic oil supplied to the steering shaft driving unit so as to be maximized when the collision determination unit determines that the state before the collision occurs.

  In the above configuration, the flow rate control unit controls the flow rate of the hydraulic oil supplied to the steering shaft driving unit so as to be maximized when the collision determination unit determines that the state before the collision has occurred. The torque is applied to the steering shaft with a strength corresponding to the flow rate of the supplied hydraulic oil.

  Therefore, in an emergency that is a state before the occurrence of a collision, the flow rate of hydraulic oil supplied to the steering shaft driving means is controlled to be maximized to ensure a sufficient operation assist force, so that a steering delay is not caused. It is possible to easily avoid danger in an emergency.

  The flow rate control unit controls the flow rate of the hydraulic oil supplied to the steering shaft driving unit based on the vehicle speed and the steering speed of the steering wheel when the collision determination unit determines that it is not in the pre-collision state. To do.

  Therefore, in normal times that are not in the state before the collision occurrence, the flow rate of the hydraulic oil supplied to the steering shaft driving means is controlled based on the vehicle speed and the steering speed of the steering wheel, so that low fuel consumption can be realized. .

  According to the present invention, it is possible to easily avoid danger in an emergency without causing a steering delay.

1 is a schematic diagram of a vehicle including a power steering device according to the present invention. It is a block diagram which shows the function structure of ECU. It is a flowchart which shows a flow control process.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram of a power steering apparatus according to the present embodiment.

  As shown in FIG. 1, the power steering device 1 includes a steering shaft 2, a power steering unit (steering shaft driving means) 3, an electronically controlled variable displacement pump 4, a flow control device (flow control means) 5, a front An object detection sensor 6, a vehicle speed sensor 7, and a steering speed sensor 8 are provided.

  The steering shaft 2 is connected to the steering wheel SW and rotates together with the steering wheel SW.

  The power steering unit 3 applies torque to the steering shaft 2 with a strength corresponding to the flow rate of hydraulic oil supplied from the electronically controlled variable displacement pump 4.

  The electronically controlled variable displacement pump 4 includes a pump main body 10 that supplies hydraulic oil to the power steering unit 3 and an electromagnetic valve 11 that adjusts the capacity (flow rate) of hydraulic oil supplied from the pump main body 10 to the power steering unit 3. ing. The pump body 10 is driven using the rotation of the engine E as a power source. The opening / closing amount of the electromagnetic valve 11 is adjusted according to a control signal from the flow control device 5.

  The flow control device 5 includes a control unit (ECU: Electric Control Unit) 12 and an electromagnetic valve 11. The ECU 12 operates upon receiving power supply from the battery B. Further, as will be described later, the ECU 12 controls the driving of the electromagnetic valve 11 based on signals received from the front object detection sensor 6, the vehicle speed sensor 7, and the steering speed sensor 8.

  The front object detection sensor 6 emits an electromagnetic wave such as a laser or a millimeter wave toward the front in the traveling direction of the vehicle, and detects the relative distance and relative speed between the object existing in front and the vehicle based on the reflected wave. The vehicle speed sensor 7 detects the current traveling speed of the vehicle from the rotation speed of the tire T and the like. The steering speed sensor 8 detects the steering speed (angular speed) of the steering wheel SW.

  FIG. 2 is a block diagram showing a functional configuration of the ECU 12.

  As shown in FIG. 2, the ECU 12 includes a CPU (Central Processing Unit) 13 and a storage unit 14. The storage unit 14 includes a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The CPU 13 functions as a collision determination unit (collision determination unit) 15 and a flow rate control unit (flow rate control unit) 16 by reading a program stored in the storage unit 14 and executing each process described below.

  The front object information from the front object detection sensor 6, the own vehicle speed information from the vehicle speed sensor 7, and the steering speed information from the steering speed sensor 8 are sequentially input to the ECU 12 every predetermined time.

  Based on information from the front object detection sensor 6 and the vehicle speed sensor 7, the ECU 12 determines whether or not it is a pre-collision state that is highly likely to come into contact with a front object, and information from each sensor. And a function of driving and controlling the electromagnetic valve 11.

  Next, the functional configuration of the CPU 13 will be described.

  As described above, the CPU 13 functions as the collision determination unit 15 that determines whether or not the vehicle is in a pre-collision state, and the flow rate control unit 16 that controls the flow rate of hydraulic oil supplied to the power steering unit 3.

  The collision determination unit 15 determines whether or not the vehicle is in a pre-collision state based on the front object information detected by the front object detection sensor 6 and the own vehicle speed information detected by the vehicle speed sensor 7.

  The flow control unit 16 controls the electromagnetic valve 11 according to the determination result of the collision determination unit 15. In a normal state that is not a state before the occurrence of a collision, the flow rate control unit 16 supplies the target flow rate based on the own vehicle speed information detected by the vehicle speed sensor 7 and the steering speed information detected by the steering speed sensor 8. A necessary command current is supplied to the electromagnetic valve 11. The target flow rate during normal time is inversely proportional to the traveling speed of the vehicle and proportional to the steering speed. In an emergency that is a state before the occurrence of a collision, the flow rate control unit 16 energizes the electromagnetic valve 11 with a command current necessary for supplying the maximum flow rate. Thereby, the flow path of the hydraulic oil in the electromagnetic valve 11 opens at an opening degree corresponding to the command current, and the hydraulic oil from the pump body 10 is supplied to the power steering unit 3.

  Next, the flow rate control process executed by the CPU 13 will be described with reference to the flowchart of FIG. This process is executed every predetermined time while the vehicle is traveling.

  When this process is started, the collision determination unit 15 determines whether or not the state is before the collision occurrence (step S1), and when it is determined that the state is not the state before the collision occurrence (step S1: NO), The flow controller 16 controls the electromagnetic valve 11 based on the vehicle speed information and the steering speed information (step S2).

  When the collision determination unit 15 determines that the emergency is the state before the collision occurs (step S1: YES), the flow rate control unit 16 controls the electromagnetic valve 11 to supply the maximum flow rate (step S3).

  According to the present embodiment, the flow control device 5 controls the flow rate of the hydraulic oil supplied to the power steering unit 3 so as to be maximized when the collision determination unit 15 determines that the state is a state before the occurrence of the collision, The power steering unit 3 applies torque to the steering shaft 2 with a strength corresponding to the flow rate of the supplied hydraulic oil.

  Accordingly, in an emergency that is a state before the occurrence of a collision, the flow rate of hydraulic oil supplied to the power steering unit 3 is controlled to be maximized to ensure a sufficient operation assisting force. It is possible to easily avoid danger in an emergency.

  Further, when the collision determination unit 15 determines that the state is not the state before the collision occurrence, the flow control device 5 changes the flow rate of the hydraulic oil supplied to the power steering unit 3 to the vehicle speed and the steering speed of the steering wheel SW. Control based on.

  Therefore, during normal times that are not in a state before a collision, the flow rate of hydraulic oil supplied to the power steering unit 3 is controlled and made variable based on the vehicle speed and the steering speed of the steering wheel SW, thereby realizing low fuel consumption. it can.

  In the present embodiment, the forward object detection sensor 6 detects the relative distance and relative speed between the forward object and the vehicle based on the reflected wave of the transmitted electromagnetic wave, but is not limited thereto, and is acquired by a camera. You may detect based on the done image.

  Moreover, the method for determining whether or not the collision determination unit 15 is in the state before the occurrence of the collision is not limited to the above method.

  Further, the flow rate control unit 16 may be able to make the target flow rate during normal times proportional to the estimated vehicle weight.

  As mentioned above, although the embodiment to which the invention made by the present inventor is applied has been described, the present invention is not limited by the discussion and the drawings that form part of the disclosure of the present invention according to this embodiment. That is, it should be added that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on this embodiment are all included in the scope of the present invention.

1 Power steering device 2 Steering shaft 3 Power steering unit (steering shaft drive means)
5 Flow control device (flow control means)
15 Collision determination unit (collision determination means)
16 Flow control unit (flow control means)
SW Steering wheel

Claims (2)

A power steering device mounted on a vehicle,
A steering shaft connected to the steering wheel;
Steering shaft drive means for applying torque to the steering shaft with a strength according to the flow rate of the supplied hydraulic oil;
A collision determination means for determining whether or not the vehicle is in a pre-collision state where there is a high possibility that the vehicle is in contact with an object existing ahead in the traveling direction of the vehicle;
Flow rate control means for controlling the flow rate of hydraulic oil supplied to the steering shaft drive means so as to be maximized when the collision determination means determines that the state is before the collision occurs. Power steering device. The power steering apparatus according to claim 1,
When the collision determination unit determines that the state before the collision has not occurred, the flow rate control unit converts the flow rate of the hydraulic oil supplied to the steering shaft driving unit to the vehicle speed and the steering wheel steering speed. A power steering device characterized by controlling based on the above.

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