JPS5814351B2 - 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, and more particularly to a novel steering force control device that changes the steering force according to the magnitude of the carrying load of a vehicle. .

Power steering device (hereinafter referred to as P)
．． (abbreviated as "S") provides an auxiliary force to the steering force of the steering wheel to enable light steering operation, and conventionally known so-called integral type, semi-integral type, and linkage type.

The linkage type is further classified into a combined type in which the power cylinder and control valve are integrated, and a separate type in which these two elements are provided separately.

By the way, these conventional P. Regardless of its type, the S always has a reaction force mechanism that transmits reaction force according to the steering output to the steering wheel in order to make the driver sense steering resistance. As one, P. A type is known in which the magnitude of the reaction force of the steering wheel is determined depending on the magnitude of the auxiliary force of the P.S. The magnitude of the auxiliary force of S is P. It is regulated by the pressure or flow rate of the fluid introduced into the working chamber of S.

In other words, P. The higher the pressure or flow rate of the fluid introduced into the working chamber of P. This means that the auxiliary force ratio of S is positive, and the reaction force of the steering wheel is relatively small.

Recently, in order to ensure running stability at high speeds, various pressure regulation or flow rate control means have been developed so that the reaction force applied to the steering wheel becomes stronger at high speeds even with the same steering output ratio (auxiliary force ratio). have been developed, but these P. All improvements to the S are aimed at detecting the speed of the vehicle and adjusting the reaction force that is applied to the steering wheel according to this vehicle speed, leaving factors other than vehicle speed completely out of consideration. ing.

The inventors of the present invention are P. In order to achieve more ideal drivability for vehicles equipped with S, especially ideal drivability for trucks whose payload changes greatly between empty and loaded, we have revised the concept of vehicle speed bias as described above. Due to the size of the live load, P. This focuses on controlling the steering output of the S.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a steering force control device in which the steering force of the steering wheel is relatively small as the load of the vehicle increases.

Another object of the present invention is that P. The flow rate of the fluid guided to the working chamber of S is controlled according to the size of the live load, and when the live load is small, the P. The purpose is to make the steering output ratio of S to be equal to that of a dog.

Another object of the present invention is to increase the P.O. The aim is to reduce horsepower consumption by not producing S output, and to avoid excessive stress and oil volume. We have improved the wear rate of each sliding part and gear part and the durability of seals by preventing it from occurring in the S system, and we have also improved the link mechanism by preventing shocks and vibrations such as kickback from being excessively suppressed by the handle. The aim is to protect the

In order to achieve the above-mentioned object, the present invention has been made by P. The system is designed to change the flow rate of fluid introduced from the oil pump into the working chamber of the vehicle according to the size of the live load, and includes a load detector that generates an output according to the live load of the vehicle, and this load detector. A fluid flow rate control means responsive to the output of the fluid is provided, and the flow rate control means controls the flow rate of the fluid, so that the larger the load is, the greater the assist force ratio to the steering force of the steering wheel is. This reduces the operating resistance of the steering wheel.

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

FIG. 1 shows a first embodiment of the present invention, in which 1 is an oil pump, 2 is a flow control valve, and the pressure oil flow from the oil pump 1 to the flow control valve 2 via a pipe line 3 is shown. Part or all is from conduit 4 to P. The process proceeds to S5, and the oil flows back to the oil pump 1 via the pipe line 6.

Further, excess fluid in the flow control valve 2 is returned to the oil pump 1 via the pipe line 7.

The flow control valve 2 has a chamber 8 communicating with the conduit 3, a chamber 9 communicating with the conduit 7, and a chamber 10 communicating with the conduit 4.
The communication area of the communication hole 11 that communicates with the chamber 10 can be controlled by a needle valve 12 that can move forward and backward into the communication hole 11, and the position of the spool valve 13 can be controlled by the pressure difference between the chamber 8 and the chamber 10. The spool valve 13 is controlled to change the area of communication between the chamber 8 and the chamber 9, and a communication groove 14 is formed at one end of the spool valve 13, that is, on the circumferential surface of the side facing the chamber 8. Further, the chamber 15 and the chamber 10, which the other end of the spool valve 13 faces, communicate with each other through a communication passage 16.

Therefore, when the amount of needle valve 12 inserted into communication hole 11 is small, the pressure difference between chamber 8 and chamber 10 is small, so spool valve 13 is located on the right side of the figure, and chamber 8 and chamber 9 However, as the needle valve 12 is inserted into the communication hole 11 and the flow area of the communication hole 11 is narrowed, the pressure difference between the chambers 8 and 10, that is, the pressure difference between the chambers 8 and 10 increases. The pressure difference between the chamber 15 and the chamber 15 becomes large, and the spool valve 13 is displaced to the left in the figure, and the chambers 8 and 9 communicate with each other through the communication groove 14.

This communication area increases as the spool valve 13 is displaced to the left in the figure, that is, the communication hole 1
The channel restricting effect of No. 1 becomes larger as the flow rate increases.

Therefore, in this flow control valve 2, the more the needle valve 12 is inserted into the communication hole 11, the more the needle valve 12 passes through the pipe line 4 and the P. The flow rate reaching S is small, and the flow rate flowing back to oil pump 1 via pipe 7 is small.

Reference numeral 17 denotes an II-F valve provided in the spool valve 13, and when the pressure on the chamber 10 side increases for some reason, pressure oil is transferred to the communication passage 16, the chamber 15, the II-F valve 17, and the communication hole 18. , and has the function of sending the oil to the pipe line 7 via the chamber 9 and refluxing it to the oil pump 1.

It is the load detector 20 that gives forward and backward movement to the twenty dollar valve 12 of the flow control valve 2.

The load detector 20 is installed between the chassis frame 21 and the axle 22 of the vehicle, or a member integrated therewith, and detects the live load based on a change in the distance between the chassis frame 21 and the axle 22, and detects the load accordingly. The output is input to a solenoid 25 via a filter 23 and a controller 24, and the solenoid 25 sucks and moves the needle valve 12 in the direction of the arrow in the figure as the load increases. , the communication area of the communication hole 11 is increased.

Note that the filter 23 removes high frequency components generated in the load detector 20 when the vehicle curves or runs on a rough road, and
This is to prevent the vibration phenomenon of 2 itself.

In this device having the above configuration, the twenty dollar valve 12 changes its position depending on the size of the vehicle's carrying load and changes the communication area of the communication hole 11. Elements such as the position of the needle center 12 and the diameter of the communicating hole 11 are determined so that the needle center 12 can be adjusted.

That is, when the load is empty, the communication hole 11 is closed by the twenty-one dollar valve 12.
The communication area between chambers 8 and 10 becomes the smallest, and the flow path area between chambers 8 and 10 becomes the most constricted.
0, that is, the pressure in the chamber 15 becomes low, and as a result, the spool valve 13 is in the most retracted state in the chamber 15, so that the communication between the chambers 8 and 9, which are communicated by the communication groove 14 on the circumferential surface of the spool valve 13, is reduced. The area is maximized.

Therefore, when the load is unloaded, the flow rate of pressure oil flowing back to the oil pump 1 via the pipe line 7 is maximum, and the flow rate of the pressure oil flowing back to the oil pump 1 via the pipe line 4 is maximum. 8
Since the flow rate ratio of pressure oil that reaches P.5 is maximum/, this P. In the S series, P. The steering output of S5 is the smallest, that is, the reaction force of the steering wheel is the largest.

In the present invention, various elements are determined in advance in consideration of this situation.

Next, at the time of loading, the load detector 20 generates an output according to the magnitude of the loaded load, and this output suction moves the twenty-one dollar valve 12 in the direction of the arrow in the figure via the controller 24 and the solenoid 25.

For this reason, the communication area of the communication hole 11 becomes larger than when the load is empty, and as a result, the throttling effect on the flow path between the chambers 8 and 10 is reduced, and the pressure on the side of the chamber 10 becomes higher than when the load is empty. The spool valve 13 is displaced to the right in the figure, reducing the area of communication between the chambers 8 and 9 through the communication groove 14. Therefore, the flow rate of pressure oil returned to the pipe line 7 is reduced, while the flow rate of the pressure oil returned to the pipe line 4 is reduced. After P. Since the amount of pressure oil supplied to S5 increases, P.
The steering output of S5 becomes a dog, and the operational resistance of the steering wheel becomes small.

In other words, when loading, P. S5
Since the steering output ratio is small and the operating resistance of the steering wheel is small, it is possible to operate the steering wheel at the same level or lighter than when the vehicle is unloaded.

In the embodiment shown in FIGS. 2 and 3, the load detector is
This shows a device that is different from the one shown in the figure, and the structure of the flow control valve 2 itself, piping, and other structures are the same as the device in FIG. 1.

Therefore, in FIGS. 2 and 3, the same components as in FIG. 1 are given the same reference numerals.

The embodiment shown in FIG.
One end of a leaf spring 27 is pivotally connected to the upper end of the leaf spring 27, and the leaf spring 27 itself is pivotally connected to the chassis frame 21 with a pin 28, and the other end of the leaf spring 27 is pivotally connected to the twenty-one dollar valve 12 of the flow control valve 2. When the chassis frame 21 and the axle 22 are loaded, the leaf spring 27 and the twenty-one dollar valve 12 are displaced in the direction of the arrow in the figure.

In the embodiment of FIG. 3, an air spring 19 is installed between the chassis frame 21 and the axle 22, and the pressure inside the air spring 19 is guided into a chamber 29 formed in the housing of the flow control valve 2.
The needle valve 12 is adapted to be displaced in the direction of the arrow as the pressure increases, that is, as the cargo load increases.

These two examples, similar to the device shown in FIG. 1, are similar to the device shown in FIG. It will be obvious that the steering output ratio of S5 is increased and the operating resistance of the steering wheel is reduced.

Note that the type of flow control valve is of course not limited to the above example, and may be, for example, a type of valve that changes the flow rate by controlling the set force of the valve spring 34, as shown in FIG. There may be.

This valve guides the fluid discharged from the oil pump 1 to two separate pipes 30 and 31, and connects one pipe 30 to the P. S
5, the other pipe line 31 is connected to a flow rate control valve 32, and the controlled flow rate of the flow rate control valve 32 is determined by the force of the spring 34 that applies a pressing force to the valve body 33 toward the valve seat side, and the force of the chamber 34. The spring seat 37 of the spring 34 changes depending on the pressure difference between 35 and 8.
can be moved forward and backward by the plunger 38, so the closer the spring seat 37 is to the valve body 33, the greater the controlled flow rate becomes.

Therefore, if the spring seat 37 is brought closer to the valve body 33 when the live load is small, the P. Since the flow rate to the S5 side increases, it becomes possible to generate a large steering output.

The forward and backward movement control of the spring seat 37, that is, the forward and backward movement control of the plunger 38, can be performed using any of the electrical type shown in Fig. 1, the mechanical type shown in Fig. 2, and the hydraulic and pneumatic type shown in Fig. 3. The plunger 38 may be displaced in the direction of the arrow in FIG. 4 in accordance with the increase.

In the embodiments of the present invention described above, no restrictions are placed on the axles on which the load detectors are provided.

Therefore, although the load may be detected on either the front axle or the rear axle, for the purposes of the present invention it is preferable to detect the loaded weight on the steering axle, ie, usually the front axle.

In addition, load detection is not carried out all the time; it is carried out once, for example, when the engine is started, and from this detected value, the above P. It is also possible to perform load correction of S.

In this sense, even if the load detector and the fluid flow rate control means are not directly connected as in the embodiment, and a person manually operates the fluid flow rate control means by looking at the output of the load detector, the P. S load correction can be performed.

When using a constantly sensitive load detector, in addition to the filter that removes high frequency components as described above, it is also possible to use a load detector with lower load detection sensitivity or response, or a damper to reduce impact loads. The load after removal may be measured.

Furthermore, P. If S is classified based on its specific configuration, especially the type of valve used, P.S. uses a spool valve. P. using S1 rotary valve. S and P with flapper valve. It goes without saying that the present invention can be applied to any type of valve.

In the above embodiment, for convenience of illustration, the flow control valve is set to P.
Although it is provided separately from S5 or the oil pump 1, the flow rate control valve is connected to P. Needless to say, it can be incorporated into the S5 or the oil pump 1 in advance.

As described above, in the steering force control device for a power steering device according to the present invention, as the load of the vehicle increases, the steering output ratio increases and the operational reaction force of the steering wheel decreases. This has the effect that the steering wheel can always be operated easily regardless of the size of the wheel.

In particular, since the present invention is provided with a flow rate control means and is adapted to control the flow rate of fluid led from the oil pump to the power steering device, the characteristic curve thereof is smaller than, for example, in the case of pressure control. The rise of is gradual;
Stable steering force can be obtained near the neutral position.

In the case of this flow rate control, the magnitude of the steering force is regulated within the upper and lower limits of the inflow flow rate to the power steering device, so there is a wide degree of freedom in selection, but the pressure drop as in the case of pressure control It has the advantage of good energy efficiency.

[Brief explanation of drawings]

FIG. 1 is a connection diagram with main parts in cross section showing an embodiment of a steering force control device according to the present invention, and FIGS. 2 and 3 are a first embodiment showing other embodiments of the present invention. Connection diagram similar to fig.
FIG. 4 is a connection diagram showing an example of another type of flow rate II valve, with main parts in cross section. DESCRIPTION OF SYMBOLS 1...Oil pump, 2...Flow control valve, 5...Power steering device, 20...Load detector.

Claims (1)

[Scope of Claims] 1. A power steering device that provides an auxiliary force to the steering force of the steering wheel, a load detector that generates an output according to the load of the vehicle,
and a fluid flow rate control means responsive to the output of the load detector, the flow rate control means increasing the flow rate of the fluid guided from the oil pump to the power steering device as the live load increases. A steering force control device for a power steering device, characterized in that it controls as follows. 2. A steering force control device for a power steering device as claimed in claim 1, wherein a load detector detects a load applied to a steering shaft of a vehicle. 3. The power according to claim 1 or 2, wherein the output of the load detector is input to the fluid flow rate control means through a filter that removes high frequency components that occur when the vehicle curves or runs on a rough road. Steering force control device for steering gear. 4. Claims 1 or 3, wherein the flow rate control means is comprised of a throttle valve mechanism that throttles the flow path from the oil pump to the power steering device, and a return path that returns excess fluid to the oil pump. A steering power pedestal device of a power steering device according to.