JPH0154229B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to power steering used in vehicles.

In general, power steering has been designed to generate a response, or in other words, a reaction force, in order to make the driver feel the weight of steering, that is, the steering resistance from the road surface.

However, if the magnitude of the reaction force is set small, excessive steering force can be obtained when the vehicle is stationary or at low speeds, but when the vehicle is moving at high speeds, the response tends to be too light and the steering tends to become unstable. Furthermore, if the magnitude of the reaction force is set large, an excessive steering force can be obtained at high speeds, but the steering response becomes too heavy when the vehicle is stopped or at low speeds.

In order to avoid such inconveniences, conventional methods have been used to change the reaction force, that is, the steering force, depending on the driving conditions, such as the internal combustion engine speed-sensitive flow rate throttle valve type or the vehicle speed-sensitive hydraulic reaction force increasing type. Power steering has been proposed, but because the range of change in reaction force is usually narrow, it is difficult to obtain the most appropriate reaction force depending on the vehicle's driving condition, and it is difficult to As such, the means for changing the reaction force became complicated, and production costs tended to increase.

The purpose and problem of the present invention is to select one steering force pattern from a plurality of steering force patterns set corresponding to the vehicle speed, so-called vehicle speed-sensitive characteristic steering force patterns according to individual differences between drivers, It enables steering operation by obtaining a reaction force suitable to the individual differences of the driver, reduces fatigue, enables safe driving, and is used in vehicles that can be manufactured easily and inexpensively. Provides power steering.

In relation to the above objects and problems, the power steering used in the vehicle of the present invention uses oil and
a pump flow control valve, a control valve having a pair of reaction chambers on opposite sides of the control valve spool, and a power cylinder;
A reaction communication passage communicates a pair of reaction chambers of the control valve with each other, and a reaction force regulating valve is formed in the valve casing with a rotor bore and opening into the rotor bore. The valve rotor is rotatably fitted into the rotor bore and adjusts the flow rate of pressure oil flowing between the ports, and the port is connected in the middle of the reaction communication passage. The actuator rotates the valve rotor, and the controller stores a plurality of steering force patterns set corresponding to the vehicle speed in advance, and adjusts the actual traveling speed of the vehicle to those patterns. the actuator is controlled by comparing and calculating one of the steering force patterns, and a pattern selection circuit is connected to the controller to select one of the steering patterns; The goal is to obtain a reaction force, so-called steering force, with vehicle speed-sensitive characteristics that suits the user's preferences.

Hereinafter, specific examples of the power steering system used in the vehicle of the present invention will be described with reference to the drawings.

1 to 3 schematically show an embodiment 10 of a power steering system for use in a vehicle according to the invention, which is applied to a cab-over type truck.

The power steering 10 includes an oil pump 11 and a flow control valve 12.
, a control valve 13 having a pair of reaction chambers 53 and 54 on both sides of a control valve spool 41, and a power cylinder 14, with reaction communication passages 16 and 1.
7 communicates the pair of reaction chambers 53, 54 of the control valve 13 with each other, and the reaction force regulating valve 15 is opened into a valve casing 18 with a rotor bore 19 and into the rotor bore 19. a pair of ports 20 and 21 formed in the valve casing 18; and a valve rotor 22 that is rotatably fitted in the rotor bore and adjusts the flow rate of pressure oil flowing between the ports 20 and 21. The ports 20 and 21 are located in the middle of the reaction communication passages 16 and 17.
and its reaction communication passages 16, 17.
The actuator 23 rotates the valve rotor 22 and the control 73
stores in advance a plurality of steering force patterns set corresponding to the vehicle speed, compares the actual traveling speed of the vehicle with one of these steering force patterns, calculates it, and controls the actuator 23, and , a pattern selection circuit 74 was constructed connected to the controller 73 to select one of the steering force patterns.

The oil pump 11 is driven by an internal combustion engine (not shown) mounted on its cab-over type truck, and pumps up oil stored in an oil reservoir (not shown) and uses the internal combustion engine. It is configured to provide a discharge amount of pressure oil that is approximately proportional to the engine speed.

The oil pump 11 is configured similarly to an oil pump used in existing power steering systems, so a description of its configuration will be omitted.

The flow control valve 12 is a pump connected to the discharge side of the oil pump 11.
Port 66, control valve 13 described later
The control terminal connected to the supply port 32 side of
Valve port 67 and its suction port connected to the suction side of oil pump 11.
It consists of a casing equipped with a port 68 and an oil return control spool (not shown) arranged so as to be able to slide back and forth within the casing, and adjusts the flow rate of pressure oil sent to the pump port 66 side. A predetermined flow rate is sent to the control valve port 67 side, and a surplus flow rate is sent from the suction port 68 to the suction side of the oil pump 11, that is, to the oil reservoir (not shown) side. configured to return.

The flow control valve 12 is a flow control valve used in existing power steering.
Since it is constructed in the same manner as the control valve, a detailed explanation of its construction will be omitted.

The control valve 13 is connected to the spool chamber 31 and its flow control valve 1.
supply port 3 connecting the control valve port 67 side of 2 to its spool chamber 31;
2. Fill the spool chamber 31 with the oil.
a discharge port 33 connected to the suction side of the pump 11, and a power cylinder port 34,
A control valve casing 30 with ports 35 and 36, connecting its supply port 32 to its exhaust port 33 and power cylinder port 3.
a control valve spool 41 reciprocally slidably disposed within its spool chamber 31 for switchable connection to 4, 35, and 36; A pair of reaction chambers 53 and 54 are formed on both sides of the chamber.

Of course, ring grooves 39 and 40 are formed within the spool chamber 31 to communicate with the supply and discharge ports 32 and 33, respectively.

Also, the control valve spool 4
1 is placed in the neutral position, its ring groove 3
Lands 42 and 45 are formed around both ends of the control valve spool 41 located outside of the lands 9 and 40, respectively.
Lands 43 and 44 are formed between 2 and 45 so as to face the ring grooves 39 and 40, respectively.

Of course, those lands 42, 43, 44, 45
In between, the power cylinder port 34, 3
5, 36 can be connected to the spool grooves 46, 47,
48 are formed respectively.

Furthermore, bores 49 and 50, which extend along the axial direction of the control valve spool 41 and are open at both ends, are formed inside both ends of the control valve spool 41. , 50 are the communicating holes 51,
52 to the spool grooves 46 and 47, respectively.

Therefore, the spool grooves 46, 47 are connected to the reaction chambers 53, 54 via the communication holes 51, 52 and the bores 49, 50, respectively.

Also, the control valve spool 4
1 is a control valve spool 41 that slides back and forth in response to steering operation.
One end of a shaft 71 is fixed at approximately the center of the shaft 71, and the other end of the shaft 71 passes through the control valve casing 30 and is connected to a steering shaft (not shown).

The supply spool 32 of the control valve 13 configured as described above is connected to the supply spool 32 via the piping 69.
It is connected to the control valve spool 67 of the flow control valve 12, and the discharge port 33 is connected to the suction side of the oil pump 11 via piping 70.

The power cylinder 14 has its control
a power cylinder casing having a cylinder bore 58 integrally formed in the casing 30 of the valve 13 and connected to the power cylinder ports 34, 35, 36 of the control valve 13; It is reciprocally slidably disposed within the cylinder bore 58 to form a pair of cylinder chambers 59, 60 correspondingly connected to the cylinder ports 34, 35, and 36 within the cylinder bore 58. Further conceptually explaining the output section, one end is connected to the power piston 61.
an operating rod 6 connected to the power cylinder casing, the other end of which protrudes outward through the power cylinder casing;
2, and a rod 6 fixed to the power cylinder casing at a position opposite the operating rod 62 and substantially coaxially with the operating rod 62.
It consists of 3.

Of course, the power cylinder ports 34 and 35 of the control valve 13 are connected to the communication path 5.
5, 56 to the cylinder chamber 60, and
The power cylinder ports 36 are each connected to their cylinder chambers 59 via communication passages 57.

In addition, it is fixed to the power piston 61,
The tip of the operating rod 62 protruding outside the power cylinder casing is attached to the chassis frame (not shown) side of the cab-over type truck; The rod 63 side fixed to the cylinder casing is shown to schematically represent the steering resistance on the tire side.

The reaction force regulating valve 15 is connected to the rotor bore 19
a pair of ports 20 and 21 formed in the valve casing 18 and opening oppositely into the rotor bore 19; The ports 20, 21 are mated together.
The valve rotor 22 which adjusts the flow rate of pressure oil flowing between the valve rotor 22, the pair of throttle grooves 28 and 29, the protrusion 25, the positioning stopper 26, and the return spring 27 are manufactured. Ta.

The valve casing 18 is manufactured in the form of a plug that is inserted into a fitting hole 64 drilled in the casing 30 of the control valve 13 at a predetermined position. The rotor bore 19 is located inside the part that is inserted into the hole 64.
A housing chamber 72 is formed inside the other end to house the actuator, position detector 24, protrusion 25, positioning stopper 26, return spring 27, and the like.

The valve rotor 22 has a pair of throttle grooves 28 and 29 on its outer circumferential surface and slides into the rotor bore 19 so as to throttle and adjust the flow rate of pressure oil flowing between the pair of ports 20 and 21. arranged so that it can rotate.

The pair of throttle grooves 28 and 29 are formed on the outer peripheral surface of the valve rotor 22 at positions correspondingly related to the pair of ports 20 and 21, as shown in FIG. As shown in FIGS. 1 and 2, the groove width and groove depth are gradually decreased in the circumferential direction so that the groove cross-sectional area is changed from one end to the other end in the circumferential direction of the valve rotor 22. Each was formed into a shape that was narrowed in turn. Of course, the aperture grooves 28 and 29 are
When the valve rotor 22 is in the illustrated starting rotation position, one end of the valve rotor 22 is connected to the corresponding port 20, 21, the other end is connected to the corresponding port 21,
20 respectively and its valve rotor 2
It is formed on the outer peripheral surface of 2.

Therefore, the flow rate of the pressure oil flowing between the ports 20 and 21 is adjusted according to the rotation of the valve rotor 22, and when the valve rotor 22 is at its rotation start position, the flow rate of the pressure oil flowing between the ports 20 and 21 is adjusted. The ports 20 and 21 are placed in the most constricted state by their constriction grooves 28 and 29.

Also, the lower portion of the valve rotor 22, ie, the shaft, is located in the storage chamber 72.
It is rotatably supported on a bearing in the bottom wall of the storage chamber 72.

The protrusion 25 is formed to protrude from the outer peripheral surface of the lower end of the shaft and rotate integrally with the shaft, that is, the valve rotor 22.

The positioning stopper 26 is embodied in an adjustment screw, drilled in the lower part of the valve casing 18 and screwed into a threaded hole into the receiving chamber 72, with its protrusion 25 at the tip. I try to accept it. Of course, the threaded hole is formed in a built-up portion of the lower portion of the valve casing 18,
The adjustment screw 26 is made to face the protrusion 25 so as to determine the rotation start position of the valve rotor 22.

Therefore, the tip of the adjustment screw 26 and the protrusion 2
5, the rotation start position of the valve rotor 22 is regulated, and by rotating the adjustment screw 26, the rotation start position of the valve rotor 22 is adjusted.

The return spring 27 is a spiral spring, and the spiral spring 27 is arranged in and located inside the storage chamber 72 so as to always return the valve rotor 22 to the starting position of rotation. One end is attached to the valve rotor 22 and the other end located outside is attached to the valve casing 1.
8 are attached to each.

The actuator 23 is a servo motor and is disposed within the housing chamber 72 of the valve casing 18 to rotate the valve rotor 22 in response to an output signal from a controller 73, which will be described below.

Further, within the storage chamber 72 and above the actuator 23, a potentiometer is provided as a rotational position detector 24 of the valve rotor 22.
A meter is placed.

Note that if a stepping motor is used instead of the servo motor 23, its position will be detected by software that feeds back which pole of the stepping motor is being energized. is desirable.

Of course, the servo motor 23 is controlled by a controller 73, which will be described later, but the servo motor 23 and the potentiometer 24
The reaction force adjusting valve 15 having a built-in reaction force adjusting valve 15 is fitted into a fitting hole 64 formed at a predetermined position in the casing 30 of the control valve 13 described above, and is bolted.

In such a fitted state, the reaction communication passages 16 and 17 are connected to the control and
Pair of reaction chambers 5 of valve 13
Ports 37 and 38 of No. 3 and 54 are connected to a pair of ports 20 and 21 of the reaction force regulating valve 15, respectively.

Of course, the reaction communication passages 16 and 17 are
The casing 30 of the control valve 13
The ports 37 and 38 of the reaction chambers 53 and 54 are connected to the pair of ports 20 and 21.
It was formed by drilling a hole in a predetermined part so as to communicate with the

Further, the reaction force adjustment valve 15 is fitted into a fitting hole 64 formed in the casing 30 of the control valve 13.
A drain chamber is formed above the
The drain chamber is connected through a communication path 65.
Exhaust port 33 of the control valve 13
side, that is, the suction side of the oil pump 11.

The controller 73 mainly includes an input and output circuit, a memory circuit, an arithmetic circuit, and a control circuit, and the memory circuit stores in advance a plurality of steering force patterns set corresponding to the vehicle speed. The actual traveling speed of the truck is compared to one of these steering force patterns, and the output signal, i.e., the output current, is calculated and output to the servo motor 2.
3, and the valve rotor 22 of the reaction force adjustment valve 15 is rotated by the servo motor 23. In this case, the plurality of steering force patterns are classified into a light side, an intermediate side, and a heavy side based on the optimum steering force determined according to the vehicle speed so as to be suitable for the truck.

The controller 73 inputs an actual traveling speed signal of the truck sensed by a speed sensor (not shown) to its input circuit, and selects a steering force selected from the plurality of steering force patterns by its pattern selection circuit 74. Based on the pattern, an output signal, ie, an output current, is applied to the electromagnetic coil of the servo motor 23.

Of course, the controller 73 automatically determines the rotational position of the valve rotor 22 in the reaction force adjustment valve 15, and always keeps the rotational position appropriate. That is, the controller receives a feed signal from a potentiometer 24 used as a rotational position detector of the valve rotor 22 or from the energized pole of a stepping motor.
Based on the back signal, the rotational position of the valve rotor 24 is corrected, and the servo motor 23 or stepping motor is controlled so that the rotational position is always appropriate.

The pattern selection circuit 74 is electrically connected to the controller 73 so as to be able to switch and select one of the plurality of steering force patterns stored in the memory circuit of the controller 73.

That is, the pattern selection circuit 74 includes a pattern select switch 75 electrically connected to the input circuit of the controller 73, and a knob 76 of the pattern select switch 75.
By rotating the controller 73
, and causes the controller 73 to operate and stop the servo motor 23 based on the selected steering force pattern. Of course, the pattern select switch 75 may have any form as long as it can select one of the plurality of steering force patterns stored in the controller 73.

Next, to describe the driving of a cab-over type truck to which the above-mentioned power steering 10 is applied, the steering force during driving is controlled by the controller 73.
The steering force pattern is automatically controlled based on a plurality of steering force patterns stored in the memory circuit of the vehicle and according to the traveling speed of the cab-over type truck. I am treated well.

Therefore, by the pattern selection circuit 74,
When the driver selects a steering force pattern with a lighter steering force, the actual running speed of the truck is detected by the speed sensor, and the detected speed signal is sent to the speed sensor. Therefore, since it is given to the controller 73, it is automatically determined in the controller 73 based on the selected steering force pattern.

That is, when such a selection is made and the truck travels at low speed, the controller 73 drives the servo motor 23 with an output current determined based on the selected steering force pattern. Then, the valve rotor 22 of the reaction force regulating valve 15 is rotated by the servo motor 23, and as a result, the pair of ports 20 and 21 are not extremely restricted.
They communicate with each other via throttle grooves 28 and 29 of the valve rotor 22.

In such a condition, the oil pump 11
The pressure oil supplied from the flow control
The flow rate is adjusted by the valve 12, and a predetermined flow rate of pressure oil is sent to the supply port 32 of the control valve 13.

When the control valve spool 41 is in the neutral position, the pressure oil sent to the supply port 32 is pumped through the exhaust port 33.
The control valve spool 41 is returned to the suction side of the pump 11, but when the control valve spool 41 is slid from the state shown in FIG. Depending on the direction, the pressure oil flows into either one of the cylinder chambers 59, 60 of the power cylinder 14 and the reaction valve of the control valve 13.
It is supplied to either chamber 53 or 54.

Now that control valve spool 41
is slid to the right in FIG.
The spool 41 is connected to its power cylinder port 36 via the spool groove 47, and the pressure oil is
The power piston 61 is sent to the cylinder chamber 59 of the power cylinder 14, and the power piston 61 is moved to the left in FIG. 1, in other words, the power cylinder 14 is moved to the right in FIG.

When pressure oil is so supplied, a portion of the pressure oil is sent to reaction chamber 54 through communication hole 52 and bore 50.

The reaction force caused by such steering is given by the pressure inside the reaction chamber 54, but as described above, when traveling at low speed by selecting the steering force pattern on the side where the steering force is lighter, the reaction force is generated by the reaction chamber 54. Since the pair of ports 20 and 21 of the force regulating valve 15 are not extremely constricted and communicate with each other with a wide passage cross-sectional area, the pressure oil in the reaction chamber 54 is transferred to the other reaction chamber. It is sent to chamber 53.

Of course, that control valve spool 4
1 is slid as described above, its discharge port 33 is communicated with its spool groove 46, so that the pressure oil in its reaction chamber 53 is returned to the suction side of the oil pump 11.

Therefore, the pressure oil in the reaction chamber 54 is transferred to the control valve spool 4.
The steering force does not create a large resistance against the sliding movement of step 1, and the steering force when traveling at low speed by selecting the steering force pattern on the side of the lighter steering force can be performed with a smaller operating force.

Also, the control valve spool 4
1 is slid to the left in FIG. Pressure oil enters the cylinder chamber 60 of the power cylinder 14,
and the reaction chamber 53 of the control valve 13, and the power piston 61 is moved to the right in FIG. 1, that is, the power cylinder 14 is moved to the right in FIG. .

The pressure oil in the reaction chamber 53 is
Contrary to the above case, the reaction communication passage 16,
17, and the reaction chamber 54 is not extremely restricted by the reaction force adjustment valve 15.
The oil in the reaction chamber 54 passes through the bore 50 and the communication hole 52 and is returned to the suction side of the oil pump 11 from the discharge port 33.

Therefore, as in the case described above, the pressure oil in the reaction chamber 53 does not provide much resistance to the sliding of the control valve spool 41, and maintains the steering force pattern on the lighter side of the steering force. Steering when selectively driving at low speed is performed with a small operating force.

Of course, when the cab-over type truck is steered while stopped, the traveling speed is zero and the cross-sectional area of the passage between the ports 20 and 21 in the reaction force adjustment valve 15 is widened to the maximum. The pressure difference between the chambers 53 and 54 becomes extremely small, and it becomes possible to turn, move, and turn with extremely small operating force.

In addition, when a steering force pattern with a lighter steering force is selected and the cab-over type truck runs at high speed, a signal from the speed sensor is input to the controller 73, and the selected steering force pattern is inputted to the controller 73. The servo motor 23 is driven based on this, the valve rotor 22 of the reaction force adjustment valve 15 rotates, and the space between the pair of ports 20 and 21 is narrowed by the valve rotor 22, and the passage cross-sectional area is narrowed.

As in the case described above, when the control valve spool 41 is slid in either the left or right direction in FIG.
Pressure oil is sent to either one of the reaction chambers 53 and 60 to cause the power piston 61 to slide, and a portion of the pressure oil is sent to either one of the reaction chambers 53 and 54, but the reaction force adjustment valve 15 ports 20, 21
Because the space between the passages is narrowed and the cross-sectional area of the passage is narrowed,
The pressure drop caused by the reaction force adjustment valve 15 increases, and the pressure difference between the left and right reaction chambers 53 and 54 increases, causing the control valve
This creates a large resistance to the sliding of the spool 41,
A relatively large operating force is required for steering when a steering force pattern with a lighter steering force is selected and the vehicle travels at high speed, and as a result, driving stability is improved.

Further, when the driver selects a heavy steering force pattern by the pattern selection circuit 74, the steering force is automatically adjusted during driving based on the selected steering force pattern and in accordance with the signal from the speed sensor. determined.

Of course, the steering force in such a case is heavier than in the above-mentioned case when compared with the same traveling speed.

Furthermore, if the servo motor 23 stops driving due to a failure of the controller 73, the spiral spring 27 disposed within the housing chamber 72 of the reaction force adjustment valve 15 will cause the valve rotor 22 to
is returned to the rotation starting position, and its pair of ports 2
The range between 0 and 21 is narrowed down to the maximum.

Therefore, a large operating force is required for steering in the event of such a failure, and extremely light and unstable steering is avoided, thereby ensuring safety.

Furthermore, since the reaction force adjustment valve 15 described above is configured in a plug type so as to be fitted into the casing 30 of the control valve 13, the reaction force adjustment valve 15 can be easily attached and removed. Flushing of the reaction force adjustment valve 15 is extremely easy, and the rotation start position of the valve rotor can be easily adjusted, resulting in good productivity, little variation in steering force, and stable quality.

As understood from the above, in the power steering used in the vehicle of the present invention, the reaction communication passage communicates the pair of reaction chambers of the control valve with each other, and the reaction force adjustment valve connects the rotor bore. a pair of ports opened in the rotor bore and formed in the valve casing; and a flow rate of pressurized oil flowing between the ports that are rotatably fitted in the rotor bore. The actuator rotates the valve rotor, and the controller connects the port in the middle of the reaction communication passage and is arranged in the reaction communication passage.
A plurality of steering force patterns set corresponding to the vehicle speed are stored in advance, the actual running speed of the vehicle is compared with one of the steering force patterns, and the actuator is controlled by calculation, and the pattern is selected. Since a circuit is connected to the controller to select one of those steering force patterns,
In the power steering used in the vehicle of this invention, one steering force pattern can be selected from a plurality of steering force patterns set according to the vehicle speed according to the individual differences of the driver. Reaction force suitable for individual differences can be obtained, in other words, it is possible to perform steering operations with vehicle speed sensitivity characteristics that are appropriate for the individual differences of the driver.As a result, fatigue caused by steering operations is reduced and safe driving is possible. In addition, since the operating force pattern is vehicle speed sensitive, it can be manufactured easily and inexpensively, making it extremely practical.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a specific example of power steering used in a vehicle of the present invention applied to a cab-over type truck, and FIG.
FIG. 3 is a cross-sectional view taken along line 3--3 in FIG. 1. 10... Power steering used in vehicles, 11... Oil pump, 12... Flow control valve, 13... Control valve, 14... Power cylinder, 15... Reaction force adjustment valve, 16, 17... Reaction connection Passage, 18...Valve casing, 19...Rotor bore, 20,
21... Port, 22... Valve rotor, 23... Actuator, 41... Control valve spool, 53, 54... Reaction chamber,
73...Controller, 74...Pattern selection circuit.

Claims (1)

[Claims] 1. Consists of an oil pump, a flow control valve, a control valve with a pair of reaction chambers on both sides of the control valve spool, and a power cylinder, and is used for steering a vehicle. in which a reaction communication passage connects a pair of reaction chambers of the control valve to each other, and a reaction force regulating valve connects a pair of reaction chambers of the control valve to each other.
A casing, a pair of ports opened in the rotor bore and formed in the valve casing, and a valve rotatably fitted in the rotor bore to adjust the flow rate of pressurized oil flowing between the ports.・The actuator rotates the valve rotor, and the actuator rotates the valve rotor, and the actuator rotates the valve rotor. a steering force pattern is stored in advance, and the actual traveling speed of the vehicle is compared with one of the steering force patterns and calculated to control the actuator, and a pattern selection circuit is connected to the controller. Power steering used in vehicles is characterized by selecting one of these steering force patterns.