JPS582100B2 - Steering force control device for power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steering force control device for a power steering device.

Conventionally, as a steering force control device for a power steering device, a variable orifice is provided in the middle of a conduit that supplies pressure oil to the working chamber of the power steering device, and the flow area of this variable orifice is adjusted according to the speed of the vehicle. A known system is known in which pressure is controlled to be generated upstream of the orifice in accordance with the vehicle speed, and this pressure is introduced into the reaction force chamber of the power steering device.

The pressure introduced into the reaction force chamber allows the driver to sense the steering force, and this steering force, or pressure, is controlled according to the vehicle speed.
The steering feels light at low speeds, and relatively heavy and stable at high speeds.

However, in variable orifice type steering force control devices, when the oil temperature changes and the oil viscosity changes, the pressure generated upstream of the variable orifice changes.
If the steering force is set to be optimal at the normal oil temperature after the engine has warmed up, there is a drawback that the steering sensation may be poor at low temperatures in the early stages of operation, and there is always a small amount of oil flow. , was accompanied by a loss of energy.

In view of these drawbacks, the present invention provides a system that does not adversely affect the steering force even if the viscosity of the oil changes in response to changes in oil temperature.
It is an object of the present invention to provide a steering force control device for a power steering device with little loss of energy.

The invention will now be described with reference to illustrated embodiments.

FIG. 1 shows a steering force control device for a power steering device according to the present invention, which is capable of controlling the steering force according to the magnitude of the live load. A power steering device (hereinafter referred to as PS) is connected via the force control device 3 and the conduit 4.

) 5 and is further returned to the oil pump 1 via a pipe 6.

A stepped hole 8 is formed in the housing 7 of the steering force control device 3, and a stepped piston 9 is slidably inserted into the stepped hole 8 to form three chambers 10, 11. , 12.

The pipe lines 2 and 4 are respectively connected to the chamber 10 facing the end face of the small diameter portion of the stepped piston 9, so that the pressure oil from the oil pump 1 can be supplied to the working chamber of the PS5 through the chamber 10. There is.

A chamber 12 facing the end surface of the large diameter portion of the stepped piston 9 communicates with the chamber 10 via an internal passage 13 formed in the housing 7, and the chamber 12 communicates with the reaction force chamber of the PS 5 via a conduit 14. ing.

Further, the chamber 12 and the chamber 11 are connected to the stepped piston 9 and the stepped hole 8.
The chamber 11 communicates with the storage tank side of the oil pump 1 via a conduit 16.

Reference numeral 17 denotes a spring that urges the stepped piston 9 upward and holds it in a non-operating position in elastic contact with a stopper 18 provided in the chamber 10. In this state, the outer circumferential surface of the stepped piston 9 is The opening of the internal passageway to chamber 10 is closed, and chamber 1
Communication between 0 and 12 is cut off.

Reference numeral 19 denotes a control mechanism connected to the stepped piston 9 and controlling the urging force that urges the stepped piston 9 upward in accordance with the magnitude of the loaded load.This control mechanism 19 is configured as follows. There is.

That is, 20 is a solenoid disposed in a housing 21 integrally connected to the housing 7, 22 is a plunger slidably inserted into the center hole of the solenoid 20, and the plunger 22 is connected to the stepped piston. It is connected to 9.

23 is a displacement meter or load detector disposed between the chassis frame 24 and the axle 25 or the leaf spring 26, which measures the amount of displacement between the chassis frame 24 and the axle 25 or the leaf spring 26 according to the live load, that is, the amount of displacement between the chassis frame 24 and the axle 25 or the leaf spring 26. Batsuteri 2
7 to the solenoid 20,
The solenoid 20 strongly urges the plunger 22, that is, the stepped piston 9, upward as the load increases.

Note that 28 is a filter that removes high frequency components generated in the displacement meter 23.

With the above configuration, the oil discharged from the oil pump 1 flows into the working chamber of the PS 5 via the pipe line 2, the chamber 10 of the steering force control device 3, and the pipe line 4, and the oil flows through the pipe line 6. It is refluxing to pump 1.

When the steering wheel is turned from this state, the hydraulic pressure in the pipe line 4 and chamber 10 on the upstream side of PS5 increases, and this pressure moves the stepped piston 9 downward against the spring 17, causing the internal passage 13 is opened, chambers 10 and 12 communicate with each other, and the increased pressure is guided to chamber 12.

When the pressure in the chamber 12 increases, this pressure, together with the spring 17, causes the stepped piston 9 to move upwardly, causing the internal passage 13 to move upwardly.
Therefore, when the resultant force of the elastic force of the spring 17, the urging force of the control mechanism 19, and the pressure in the chamber 12 becomes greater than the increased pressure, the internal passage 13 is closed.

Note that the chamber 12 communicates with the storage tank side of the oil pump 1 via the relief passage 15, the chamber 11, and the conduit 16, and the relief passage 15 has a function as an orifice passage.
The pressure inside the chamber 12 gradually decreases, but when the pressure inside the chamber 12 decreases, the internal passage 13 opens again and pressure is introduced, so the pressure inside the chamber 12 is maintained at a nearly constant value. .

The pressure within this chamber 12 is then introduced into the reaction force chamber of the PS5 via the conduit 14, so that the driving vehicle senses a steering force that corresponds to the increased pressure, in other words, a steering force that corresponds to the steering resistance. be able to.

However, when the live load is small, the upward force applied to the stepped piston 9 by the solenoid 22 is small, so the second
As shown by straight line a in the figure, the pressure in the chamber 12, that is, the pressure in the reaction force chamber, increases rapidly as the pressure in the chamber 10, that is, the pressure in the working chamber increases.

Therefore, a reliable steering feeling can be obtained even when the vehicle is under a light load with low steering resistance or when the vehicle is empty.

On the other hand, when the load is large, the stepped piston 9
As the force exerted by You can get a light steering feel.

The pressure introduced into the reaction force chamber is not the pressure generated on the upstream side of the orifice as in the conventional variable orifice type steering force control device, but is the pressure that balances the stepped piston 9. Even if the viscosity of the reaction force chamber changes, the pressure introduced into the reaction force chamber does not change.

Next, FIG. 3 shows an embodiment using a control mechanism 19 that can control the biasing force of the stepped piston 9 depending on the speed of the vehicle.

In the figure, a solenoid 20, a housing 21, and a plunger 22 are constructed in the same manner as in FIG.

29 is a rotating cable of the speedometer 31 pulled out from the output shaft of the transmission 30, and in the middle of this rotating cable 29, the rotation speed of the rotating cable 29 is detected,
A speed detector 33 is provided to control the current flowing from the battery 32 to the solenoid 20 accordingly.

This detector 33 controls the energizing current so that the force applied to the stepped piston 9 by the solenoid 20 becomes smaller as the speed of the vehicle increases.

Therefore, when driving at low speeds, the biasing force of the stepped piston 9 increases, and as shown by the straight line b in FIG. Guaranteed sensation.

On the contrary, when running at high speed, the biasing force of the stepped piston 9 becomes smaller, and the pressure in the reaction chamber quickly increases as the pressure in the working chamber increases, as shown by straight line a in FIG. ,
Therefore, a relatively heavy and stable steering force can be obtained during high-speed driving with little steering resistance.

In the above two embodiments, the biasing force of the stepped piston 9 can be changed separately depending on the load or the speed, but the biasing force can also be changed depending on both.

For example, when electrically changing the biasing force of the stepped piston 9 as in the above embodiment, the current from the displacement meter 23 and the current from the speed detector 33 are added, and when the vehicle speed is the minimum and the load is the maximum, The biasing force of the stepped piston 9 may be maximized when the vehicle is a dog, and the biasing force of the stepped piston 9 may be minimized when the vehicle speed is maximum and the load is minimal.

FIG. 4 shows still another embodiment of the present invention, in which the stepped piston 9 is replaced by a piston 9' whose both ends have the same diameter.

When this piston 9' is used, the relationship between the pressure in the working chamber of PS5 and the pressure in the reaction force chamber of PS5 is as shown in FIG.

In addition, the pressure receiving area of the stepped piston facing the chamber 12 side is
When the area is set smaller than the pressure receiving area facing the side, the relationship between the pressure in the working chamber and the pressure in the reaction force chamber becomes as shown in FIG.

Note that the symbols a and b in FIGS. 5 and 6 correspond to the symbols a and b in FIG. 2, respectively.

For example, when a mechanical means is used as the control mechanism 19, if the means does not allow the piston 9' to retreat, the piston 9' may be slidably fitted into the hole 8' as shown in FIG. The control mechanism 16 is interlocked with the matched spring seat 36,
A spring 3 is loaded between the spring seat 36 and the piston 9'.
The piston 9' may be energized via the piston 7.

Furthermore, an escape passage 15 for letting the oil in the chamber 12 escape to the outside, an internal passage 38 bored in the piston that communicates between the chambers 10 and 12, and an internal passage 38 provided in this passage for allowing oil to flow from the chamber 12 to the chamber 10. It is also possible to configure it with a one-way check valve 39 that allows.

Furthermore, in each of the above embodiments, the stopper 1
8 is provided in the housing 7, but it may also be provided on the piston 9, 9' side, and in the stepped piston 9, the stepped portion may be used as a stopper.

As described above, in the present invention, a piston is slidably fitted into a hole formed in a housing, and chambers are defined at both ends of the piston, and an oil pump and a power steering device are connected to each other through one chamber. and the other chamber communicates with the reaction chamber of the power steering device, and the piston communicates the oil pump with the reaction chamber of the power steering device. The piston is communicated with through a passage that is cut off when the piston is in the non-operating position displaced toward the room, and the piston is energized to the non-operating position, and the magnitude of the load and the vehicle speed are controlled. A control mechanism is connected to control the applied force according to either or both of the magnitude of In addition to being able to obtain the optimal steering force depending on either or both of the load and vehicle speed,
The pressure introduced into the reaction force chamber is the pressure that balances the piston, so there is no need to change the steering force due to changes in oil viscosity, which is the case with conventional methods. This has the effect of reducing loss compared to conventional variable orifice type steering force control devices that require flow to the orifice.

[Brief explanation of the drawing]

FIG. 1 is a systematic connection diagram showing an embodiment of the present invention with main parts in cross section, FIG. 2 is a characteristic curve diagram obtained by the steering force control device shown in FIG. 1, and FIG. 3 is a diagram showing another embodiment of the present invention. A systematic connection diagram with the main part of the example in cross section, FIG. 4 is a systematic connection diagram with the main part of another embodiment in cross section, and FIG. 5 is obtained by the steering force control device shown in FIG. 4. Characteristic Curve Diagram FIG. 6 is a characteristic curve diagram obtained by a steering force control device having a further configuration not shown. 1... Oil pump, 3... Steering force control device, 5... Power steering device, 7...
Housing, 8...Stepped hole, 8'...
Hole, 9...Stepped piston, 9'...Piston, 10, 12...Chamber, 13...
Internal passage, 15...Escape passage, 19...
・Control mechanism.

Claims (1)

[Claims] 1. A piston is slidably fitted into a hole formed in the housing to define chambers at both ends thereof, and the oil pump and the working chamber of the power steering device are communicated through one chamber, The other chamber is communicated with the reaction chamber of the power steering device, and both chambers are moved to a non-operating position in which the piston is displaced toward a chamber that communicates the oil pump with the working chamber of the power steering device. The piston is connected to the piston via a passage that is cut off when the piston is in the non-operating position, and the piston is energized to the non-operating position, and either one of the magnitude of the live load, the magnitude of the vehicle speed, or A steering force control device for a power steering device, characterized in that a control mechanism for controlling the auxiliary force according to both is connected, and further provided with a relief passage for letting oil in the chamber communicating with the reaction force chamber escape to the outside. .