JPH0215741Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a power steering device.

Power steering devices are equipped with a mechanism that automatically adjusts the discharge amount of the oil pump supplied to the power steering operating part to ensure stable steering operation at all times according to the driving conditions of the vehicle. is known, and one such adjustment mechanism is an engine speed sensitive type.

In this engine speed sensitive type, as the engine speed increases, the amount of oil discharged from the engine sensitive oil pump that supplies the power steering operating section decreases, and the steering force of the steering wheel becomes heavier.

However, in the case of such an engine speed sensitive type, the amount of oil discharged changes every time the gear shaft of the transmission is activated. That is, during a gear shift, the engine side and the transmission side are disconnected and the engine is temporarily in an unloaded state, so the accelerator is normally released to reduce the engine speed. For this reason, the amount of oil discharged from the engine-sensitive oil pump that is supplied to the power steering operating section temporarily decreases due to the increase in engine speed when the engine and transmission sides are disconnected and a no-load condition occurs. However, when the accelerator is released, the engine speed decreases and immediately increases. Therefore, as shown in Fig. 1, as the vehicle speed increases, the overall oil discharge amount decreases and the steering force becomes heavier, which is safe, but every time the transmission gear shifts. Furthermore, the oil flow rate to the power steering operating section changes in stages, which causes the steering force to fluctuate, which is not very desirable in terms of steering feeling. In the figure, 1st, 2nd, 3rd, and 4th indicate shift positions, and 1000 rpm and 5000 rpm indicate engine speed.

This idea was made in view of the above circumstances.
By combining the engine speed-sensitive type and vehicle speed-sensitive type, we have created a configuration that functions as a vehicle speed-sensitive type when a vehicle speed signal is input, and as an engine speed-sensitive type when a vehicle speed signal is not input, thereby solving the conventional problems. purpose.

Incidentally, the present applicant has proposed Utility Model Application No. 173207-1987 (Utility Model Application No. 78277-1988) regarding a combination of vehicle speed-sensitive power steering and engine speed-sensitive power steering.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

In FIG. 2, a power steering operating section 1 is provided with a power steering gearbox.
An oil passage 2 connecting an oil inlet and an oil outlet includes an oil reservoir 3, an oil pump 4, and a flow rate control valve 5 in order from the oil outlet side.
A bypass passage 6 is provided in parallel with the main oil passage 2A passing through the power steering operating section 1.

The oil pump 4 is of an engine-sensitive type configured to reduce the amount of oil discharged to the power steering operating section 1 as the engine speed increases. A vehicle speed sensor 8, which is a vehicle speed detecting means provided in the transmission, is provided at the connection between the main oil passage 2A and the bypass passage 6 between the side and the oil inlet side of the power steering actuating part 1, and the flow rate control. Controller 9 as control means for valve 5
The oil flow rate in the main oil passage 2A and the bypass passage 6 is controlled according to the vehicle speed signal sent via the vehicle speed signal, and the opening degree of the main oil passage 2A is decreased as the vehicle speed increases. The oil flow rate on the passage 2A side is decreased as the vehicle speed increases.
Furthermore, the flow control valve 5 is configured to fully close the bypass passage 6 and fully open the main oil passage 2A when no vehicle speed signal is input. In the figure, 10 is a clutch, 11 is an engine body, 12 is a radiator, and 13 is a cooling fan.

In this configuration, since the oil discharge amount of the oil pump 4 changes depending on the engine speed,
As in the past, when the transmission 7 shifts gears, the amount of oil discharged varies temporarily. However, in this embodiment, a flow rate control valve 5 is provided between the power steering operating section 1 and the discharge side of the oil pump 4, and when a vehicle speed signal is input from the vehicle speed sensor 8 to the controller 9 while the vehicle is running, the vehicle speed increases. By controlling the opening degree of the main oil passage 2A to decrease in accordance with this, the oil flow rate on the main oil passage 2A side is regulated by the flow rate control valve 5 instead of the oil pump discharge amount. Therefore, when the vehicle is running, the amount of oil supplied to the power steering operating section 1 changes depending on the vehicle speed, and the remaining oil is supplied to the bypass passage 6.
I try to let it escape to the side. Therefore, under normal conditions, it functions as a vehicle speed sensitive type. Therefore, when the transmission 7 shifts gears, the vehicle speed hardly changes even if the engine speed changes.
The amount of oil supplied to the power steering operating section 1 is not affected by changes in the amount of oil discharged from the oil pump 4, and there is no sudden change before and after a gear shift. Therefore, the oil flow rate to the power steering operating section 1 changes continuously according to the vehicle speed, as shown by the solid line a in Fig. 3, so that the steering force does not fluctuate suddenly during gear shifting, and the steering feeling is improved. can be improved. Note that the shaded area in FIG. 3 indicates the amount of oil bypassed.

Further, in this embodiment, when the vehicle speed detection section such as the vehicle speed sensor 8 or the controller 9 fails and the vehicle speed signal is no longer input to the flow control valve 5, the flow control valve 5 closes the bypass passage 6 and closes the main oil passage. 2
A is fully opened, so at this time oil pump 4
Since the steering force is determined in accordance with the oil discharge amount, it functions as an engine speed sensitive type (characteristic indicated by the dashed line b in FIG. 3). Therefore, even if the above-mentioned failure occurs during high-speed driving, the oil flow rate to the power steering operating section 1 decreases and the steering force becomes heavier, so it is safe.

As described above, according to the present invention, since the vehicle operates as a vehicle speed sensitive type during normal driving, it is possible to prevent a sudden change in steering force during gear shifting of the transmission and improve the steering feeling. Also,
Even if the vehicle speed detection section malfunctions, it operates as an engine speed sensitive type, so that it is possible to obtain a good steering wheel operation suitable for the driving condition, and to provide a highly safe power steering device.

[Brief explanation of the drawing]

Fig. 1 is an oil flow characteristic diagram of an engine speed sensitive power steering device, Fig. 2 is a schematic configuration diagram showing one embodiment of the power steering device of the present invention, and Fig. 3 is an oil flow characteristic diagram of the same embodiment. shows. DESCRIPTION OF SYMBOLS 1... Power steering operating part, 2... Oil passage, 2A... Main oil passage, 4... Oil pump, 5... Flow rate control valve, 6... Bypass passage,
8...Vehicle speed sensor, 9...Controller.

Claims (1)

[Scope of utility model registration request] An oil passage connecting the oil inlet and outlet of the power steering operating section includes an engine-sensitive oil pump whose oil discharge amount changes depending on the engine speed, and a power steering operating section located on the pump discharge side. a bypass passage connected in parallel so as to bypass the power steering operating section, and a connection between the main passage and the bypass passage between the oil pump discharge side and the oil inlet side of the power steering operating section; and a flow control valve provided in the main passage to control the oil flow rate in both passages, and a vehicle speed detection means, and a main passage valve that reduces the opening degree of the main passage as the vehicle speed increases when a vehicle speed signal is input from the vehicle speed detection means. The flow rate control valve is driven and controlled to adjust the oil flow rate on the passage side to a value corresponding to the vehicle speed, and when the vehicle speed signal is not input, the main passage side is fully opened and the bypass passage side is fully closed, so that the oil flow rate on the main oil passage side is adjusted to the oil flow rate. 1. A power steering device comprising a control means for driving and controlling a flow rate control valve to adjust the flow rate to a value corresponding to a pump discharge amount.