JPH032469Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a steering force control device for power steering.

[Prior Art] A steering force control device for power steering changes, for example, the steering force associated with the driver's steering operation depending on the vehicle speed.
It operates so that it has an appropriate weight at medium and high speeds.

A conventional power steering steering force control device, for example, as shown in FIG. 3, includes a hydraulic switching valve 10 that is controlled by a handle, and a high-pressure oil line 2 that sends pressure oil from an oil pump P to the hydraulic switching valve 10.
0, a low pressure oil passage 30 that sends pressure oil from the hydraulic switching valve 10 to the reservoir T, and 2 of the hydraulic switching valve 10.
One of the switching ports 13 and 14 (for example, the switching port 13) and the power cylinder 40 of the power steering device
The first hydraulic passage 7 communicates with one of the working chambers 42 of the
0, a second hydraulic passage 80 which communicates the other switching port 14 of the hydraulic switching valve 10 with the other working chamber 14 of the power cylinder 40, and one end connected to the first hydraulic passage 70 and the other end. A bypass passage 96 is connected to the second hydraulic passage 80 and is provided with a solenoid valve 95.

[Problems to be solved by the present invention] In order to obtain a steering force suitable for the vehicle speed, a conventional power steering steering force control device adjusts the opening timing and opening area of a variable throttle section provided in the solenoid valve 95. At the same time, when the handle is turned to the right, the pressure oil in the second hydraulic passage 80 flows through the bypass passage 96 and the solenoid valve 9.
5 and is bypassed to the first hydraulic passage 70.
Also, when turning left, the pressure oil in the first hydraulic passage 70 flows through the bypass passage 96 and the solenoid valve 95 to the second hydraulic passage 8.
Bypassed to 0. This reduces the assist force of the power cylinder 40 and provides high-speed stability.

In this way, when the handle is turned to the right and to the left, the flow of pressure oil that bypasses the bypass passage 96 and the solenoid valve 95 is in opposite directions. The problem in this case is that the shape of the passage (not shown) inside the solenoid valve 95 is complicated, and there are variations in the precision of the parts that make up the solenoid valve, so as mentioned above, the bypass flow of pressure oil is caused by the shape of the passage. The flow coefficient and flow force of the passage are different for the forward and reverse flows flowing along the passage. etc., and a flow rate difference occurs in the bypass flow of the pressure oil in the forward and reverse directions. (this is,
When the handle is turned to the right, a bypass flow acts on one of the working chambers of the power cylinder, and when the handle is turned to the left, the bypass flow acts on the other working chamber of the power cylinder, resulting in a pressure difference between the two working chambers. . ) Therefore, when the solenoid valve is opened to the same degree, the steering force exerted by the steering wheel is not balanced and becomes unstable when the steering wheel is turned to the right and to the left.

[Means for Solving the Problems] The present invention provides the following means for solving the above-mentioned conventional problems.

That is, the steering force control device for power steering according to the present invention includes a hydraulic switching valve controlled by a handle, a high-pressure oil path that sends pressure oil from an oil pump to the hydraulic switching valve, and a hydraulic switching valve that sends pressure from the hydraulic switching valve to a reservoir. a low-pressure oil passage that sends oil; a first hydraulic passage that communicates between one of the two switching ports of the hydraulic switching valve and one working chamber of a power cylinder of the power steering device;
A power steering steering force control device including a second hydraulic passage communicating between the other switching port of the hydraulic switching valve and the other working chamber of the power cylinder, one end of which is connected to the high pressure oil passage and transmits a vehicle speed signal. connecting a bypass passage having a variable throttle portion controlled by the bypass passage, the other end of the bypass passage and the first hydraulic passage;
A first branch passage having a first check valve that allows only the pressure oil from the bypass passage to pass therethrough, and the other end of the bypass passage and the second hydraulic passage are connected to each other, and the second hydraulic passage is connected to the first branch passage that allows only the pressure oil from the bypass passage to pass therethrough. The present invention is characterized in that it has a second branch passage having a first check valve therethrough, and fixed throttle portions on the first and second hydraulic passages.

With this configuration, when the bypass passage maintains a constant opening degree by the variable throttle part, pressure oil is released from the high-pressure oil passage when the driver turns the steering wheel to the right or to the left. The bypass flow flows through the bypass passage and the variable throttle section in the same direction. Therefore, the fluid resistance of the fluid passages to the bypass flow does not differ, causing no difference in the bypass flow rate. Further, the pressure acting on one of the working chambers of the power cylinder is balanced between right-hand turning and left-hand turning, and the steering force becomes stable.

The steering force control device for power steering according to the present invention includes a hydraulic switching valve, a high pressure oil path, a low pressure oil path, a power cylinder of a power steering device, and a variable throttle section.
The components include a bypass passage, a first hydraulic passage, a second hydraulic passage, a first branch passage, a second branch passage, a first check valve, and a second check valve.

Among the components, a hydraulic switching valve, a high pressure oil line,
A low pressure oil passage, a power cylinder of a power steering device,
The first hydraulic passage and the second hydraulic passage can basically be the same as conventional ones.

The features of the present invention include a bypass passage, a variable throttle section,
First branch passage, second branch passage, first check valve, second
It's in the check valve.

The bypass passage has one end connected to the high pressure oil passage, and the other end connected to the first branch passage and the second branch passage on the downstream side. The bypass passage has a variable throttle portion and is a passage through which the pressure oil of the high pressure oil passage is sent to the first hydraulic passage and the second hydraulic passage.

The variable throttle section is installed in the bypass passage upstream of the first branch passage and the second branch passage, and is controlled by, for example, a computer that receives a vehicle speed signal from a vehicle speed sensor, and controls the opening timing and opening area of the bypass passage. It is something to control. A solenoid valve can be used as the variable restrictor.

The first branch passage has a first check valve, and has one end connected to the bypass passage and the other end connected to the first hydraulic passage, so that the bypass flow of pressure oil from the bypass passage is directed to the first hydraulic passage.
It is sent to the hydraulic passage.

The second branch passage has a second check valve, and has one end connected to the bypass passage and the other end connected to the second hydraulic passage, so that the bypass flow of pressure oil from the bypass passage is transferred to the second hydraulic passage.
It is sent to the hydraulic passage.

The first check valve and the second check valve are installed in the first branch passage and the second branch passage, and allow only the pressure oil from the bypass passage to pass therethrough. In addition, when pressure oil from the pump is acting on the first hydraulic passage and one of the working chambers of the power cylinder, only the second branch passage is opened and the bypass flow of the pressure oil from the bypass passage is diverted to the second hydraulic passage. Supply to hydraulic passage. In addition, when pressure oil from the pump is acting on the second hydraulic passage and the other working chamber of the power cylinder, only the first branch passage is opened and the bypass flow of pressure oil from the bypass passage is diverted to the first branch passage. 1
It supplies the hydraulic passage.

Further, the first check valve opens the first branch passage in a direction to send the bypass flow of pressure oil to the downstream side of the first branch passage, and the second check valve opens the bypass flow of pressure oil to the second branch. The second branch passage is opened in the direction of sending out to the downstream side of the passage. Thereby, the pressure oil from the bypass passage can be passed only to the downstream side of the first branch passage or only to the downstream side of the second branch passage.

[Function] By operating the hydraulic switching valve using the handle, high-pressure oil pressure from the pump is supplied to one pressure chamber of the power cylinder, and discharged oil from the other pressure chamber is discharged to the reservoir. The power assist from this power cylinder allows for easy steering. On the other hand, the opening degree of the variable throttle section is controlled by the vehicle speed signal. For example, when the vehicle is running at high speed, the opening degree of the variable throttle section is set to be large, and this bypass flow is discharged to the reservoir via the bypass passage. This reduces the assist force from the power cylinder, making the steering wheel heavier and providing high-speed stability.Also, when driving at low speeds, the variable throttle part is closed, so there is no bypass of pressure oil from the bypass passage, and the power cylinder assists. The force works effectively and the steering wheel can be operated easily.

[Effects] In the case of the present invention, there is a bypass passage whose one end is connected to a high pressure oil passage, and the bypass passage is connected to the other end of the bypass passage, each of which is provided with a check valve, and whose other ends are connected to a first hydraulic passage and a second hydraulic passage. A first branch passage and a second branch passage connected to
It has branch passages. Thereby, when the handle is turned to the right or left, the pressure oil from the high pressure oil passage can be passed through the bypass passage only to either the first branch passage or the first branch passage. In addition, when turning to the right or turning to the left, the bypass flow of pressure oil flowing through the bypass passage and the variable throttle section installed in the bypass passage can flow in one direction from upstream to downstream without flowing in the opposite direction. .

Therefore, when the opening degree of the bypass passage by the variable throttle part is the same, the bypass passage and the first
A bypass flow with no difference in flow rate can be obtained in a well-balanced manner with respect to the amount of pressure oil flowing into either the branch passage or the second branch passage. Further, the steering force associated with turning the steering wheel to the right and the steering force when turning the steering wheel to the left are equal and stable.

In addition, by controlling the discharged oil from the power cylinder with the variable throttle part and merging the bypass flow with this discharged oil, the back pressure in the pressure action chamber of the power cylinder increases, and by slightly changing the opening degree of the variable throttle part. It becomes possible to greatly change the assist force, and the adjustment range can be widened.

[Embodiment] An embodiment of the power steering steering force control device of the present invention will be described based on FIGS. 1 and 2. FIG.

The steering force control device for power steering according to the embodiment includes a hydraulic switching valve 10 consisting of a servo valve, a high pressure oil passage 20, a low pressure oil passage 30, a power cylinder 40 of a power steering device, a variable throttle portion 50, a bypass passage 60,
First hydraulic passage 70, second hydraulic passage 80, first branch passage 90, second branch passage 91, first check valve 90
1 and a second check valve 911 as constituent elements.

The hydraulic switching valve 10 is composed of a main body A, a sleeve 15 housed within the main body A, and a rotor 16 that rotates within the sleeve 15 by operation from a handle. The main body A has a high pressure oil port 11 connected to the oil pump P, a low pressure oil port 12 connected to the reservoir T, and two switching ports 13, 1.
It is equipped with 4. The sleeve 15 is connected to each port 1.
1, 13, 14, and annular grooves 111, 131, 1 connected to the first branch passage 90 and the second branch passage 91.
It is equipped with 41. The sleeve 15 and rotor 1
It rotates relative to 6. As is well known, the sleeve 15 and the rotor 16 have long grooves and lands spaced apart in the axial direction on the inner and outer circumferential surfaces of the sleeve 15 and the rotor 16, respectively. The high pressure oil port 11 and the switching port 14 can be communicated with each other, and the switching port 13 and the low pressure oil port 12 can be communicated with each other by creating a phase shift between the high pressure oil port 11 and the switching port 14. Further, when the handle is turned to the left, the high pressure oil port 11 and the switching port 13 can be communicated with each other, and the switching port 14 and the low pressure oil port 12 can be communicated with each other in the same manner. The high pressure oil passage 20 has one end connected to the pump P and the other end communicated with the high pressure oil port 11. The low pressure oil passage 30 has one end connected to the low pressure oil port 12 and the other end communicated with the reservoir T. A power cylinder 40 of the power steering device forms one pressure action chamber 42 and the other pressure action chamber 43 with a piston 41 as a boundary. A solenoid valve 501 is used as an example of the variable throttle section 50. The solenoid valve 501 is installed in the bypass passage 60, and a solenoid 502 is controlled by a computer (not shown, the same applies hereinafter) that receives a vehicle speed signal from a sensor corresponding to the vehicle speed. The spool 504 is suctioned toward the yoke 503 to control the opening timing and opening area of the variable throttle section 50. The bypass passage 60 has one end connected to the high pressure oil port 11
The other end is connected to the high pressure oil passage 20 via the first branch passage 90 and the first branch passage 91 .
The first branch passage 90 and the first branch passage 91 have one end connected to the bypass passage 60, and the other end connected to the first branch passage 90, which will be described later.
A first check valve 901 that communicates with the hydraulic passage 70 and the second hydraulic passage 80 and allows pressure oil to pass only to the downstream side, respectively.
and a second check valve 911. The first hydraulic passage 70 communicates at one end with one switching port 13 of the hydraulic switching valve 10 and at the other end with one pressure application chamber 42 of the power cylinder 40 . In addition, the first
The hydraulic passage 70 and the second hydraulic passage 80 are provided with fixed throttle portions 71 and 81 between the switching ports 13 and 14 of the hydraulic switching valve 10. Furthermore, the fixed throttle parts 71 and 81 and the variable throttle part 5 of the bypass passage 60
0, the power cylinder 40
The pressure of the bypass flow acting on both the working chambers 42 and 43 is determined.

Next, the operation of the embodiment configured as described above will be explained.

When the driver turns the steering wheel to the right,
The high pressure oil passage 20 communicates with the other pressure application chamber 43 of the power cylinder 40 via the high pressure oil port 11, the switching port 14, the second oil pressure passage 80, etc. by the oil pressure switching valve 10. Pressure oil from the pump P acts on the piston 41. At the same time, one pressure chamber 42 of the power cylinder 40 communicates with the low pressure oil passage 30 via the first oil pressure passage 70 and the switching port 13. As a result, the power assist of the power cylinder 40 allows the driver to easily operate the steering wheel. On the other hand, the solenoid valve 501 is controlled here by a command from a computer that receives a vehicle speed signal from a vehicle speed sensor. For example, when the vehicle is running at low speed, the solenoid valve 501 is not operated by a command from the computer, and the bypass passage 60 therefore remains closed. Therefore, the entire pressure oil from the high pressure oil passage 20 is supplied to the other pressure action chamber 43 of the power cylinder 40 from the high pressure oil port 11. As a result, the hydraulic pressure in the other pressure chamber 43 of the power cylinder 40 increases, creating a pressure difference between the two pressure chambers 42 and 43, and the power assist of the power cylinder 40 allows for light steering operation.

Also, when the handle is turned to the left, the hydraulic switching valve 10
Accordingly, the high pressure oil passage 20 communicates with one pressure application chamber 42 of the power cylinder 40 via the high pressure oil port 11, the switching port 13, the first hydraulic passage 70, etc. Pressure oil from the pump P acts on the piston 41. At the same time, the other pressure chamber 43 of the power cylinder 40 communicates with the second hydraulic passage 80 and the switching port 14 with the low pressure oil passage 30. Also, the solenoid valve 5
0 is controlled by a command from a computer that receives a vehicle speed signal from a vehicle speed sensor, similar to when the steering wheel is turned to the right. For example, when the vehicle is traveling at high speed, the solenoid valve 501 is actuated by a command from the computer to open the variable throttle section 50, and its opening degree is controlled according to the vehicle speed. Therefore, the pressure oil from the high pressure oil passage 20 becomes a bypass flow from the high pressure oil port 11 and flows through the bypass passage 60, and flows through the second branch passage 91.
The second check valve 911 of the first branch passage 90 is opened (the first check valve 901 of the first branch passage 90 is closed by the pressure of the pressure oil of the first hydraulic passage 70), and the bypass flow of pressure oil is directed to the bypass passage. It flows from the upstream side of 60 to the second branch passage 91 on the downstream side. By discharging a portion of the pressure oil supplied from the pump P to the reservoir T via the bypass passage 60 and the second hydraulic passage 80 in this way, the power assist force of the power cylinder 40 is reduced and the handle becomes heavy. Provides high speed stability. Also at this time, the power cylinder 40
The oil discharged from the pressure action chamber 42 is discharged through the fixed constriction part 81.
By combining this discharged oil with bypass oil from the bypass passage 60, the back pressure in the other pressure acting chamber 43 of the power cylinder 40 increases, and as a result, the power assist of the power cylinder 40 is controlled by The force is smaller and can increase high speed stability.

As described above, according to the present invention, the bypass flow of pressure oil flowing through the solenoid valve and the bypass passage always flows from the upstream side to the downstream side, and does not flow backwards, regardless of whether the handle is turned to the right or left. This is a configuration in which no bypass flow rate difference occurs. Therefore,
Stable steering force can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a power steering steering force control device of the present invention, FIG. 2 is a hydraulic circuit diagram in FIG. 1, and FIG. 3 is a hydraulic circuit diagram showing a conventional case. 10... Hydraulic switching valve, 20... High pressure oil path, 30
...Low pressure oil passage, 40...Power cylinder of power steering device, 50...Variable throttle section, 60...Bypass passage, 70...First hydraulic passage, 80... Second hydraulic passage, 90...No. 1 branch passage, 91...2nd branch passage, 901...1st check valve, 911...2nd check valve.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A hydraulic switching valve controlled by a handle, a high-pressure oil line that sends pressure oil from an oil pump to the hydraulic switching valve, and a hydraulic oil passage that sends pressure oil from the hydraulic switching valve to a reservoir. a first hydraulic passage communicating between one of the two switching ports of the hydraulic switching valve and one working chamber of the power cylinder of the power steering device; and another switching port of the hydraulic switching valve. A power steering steering force control device including a second hydraulic passage that communicates a port with the other working chamber of the power cylinder includes a variable throttle portion connected at one end to the high-pressure oil passage and controlled by a vehicle speed signal. a first branch passage that connects the other end of the bypass passage with the first hydraulic passage and has a first check valve that allows only pressure oil from the bypass passage to pass; connecting the other end and the second hydraulic passage;
A power steering system characterized in that it has a second branch passage having a second check valve that allows only the pressure oil from the bypass passage to pass through, and a fixed throttle part disposed in the first and second hydraulic passages. Steering force control device. (2) The first check valve opens the first branch passage in a direction to send the bypass flow of pressure oil to the downstream side of the first branch passage, and the second check valve opens the bypass flow of pressure oil to the second branch passage.
A power steering steering force control device according to claim 1, wherein the second branch passage is opened in a direction in which the second branch passage is sent downstream of the branch passage. (3) The power steering force control device according to claim 1, wherein the variable throttle part is a solenoid valve that controls the opening timing and opening area of the bypass passage according to a vehicle speed signal.