JPH01197171A - Power steering used for automobile - Google Patents

Abstract

PURPOSE:To suppress response delay against handle operation so as to improve steering performance by controlling pressure difference between a pair of reaction force chambers in a control valve through a pressure difference regulation valve in response to the speed of an automobile, and controlling drive pressure oil through a variable throttle in response thereto. CONSTITUTION:A control valve 13 is of oil pressure reaction type and has a pair of reaction chambers at both sides of a spool 40. In this case, a reaction force regulating passage 16 communicating the chambers with each other is provided, on the way of which passage 16, a pressure difference regulating valve 17 is provided. Further, a variable throttle 18 is provided on an oil pressure piping 72 on the upstream side of the control valve 13, and the upstream side of this variable throttle 18 is connected to an oil pressure piping 73 on the return side by a bypass 78, on which a flow regulation valve 19 is provided. The variable throttle 18 is controlled by a control unit 20 such that it increases flow according to increase in the speed of automobile.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to power steering systems used in automobiles;
In particular, it relates to power steering that improves response magnitude and response delay.

BACKGROUND ART In general, speed-sensitive power steering has become popular in automobiles.Increasing the sensitivity of this type of power steering reduces response delay and improves maneuverability, but the steering wheel angle There was a tendency for the tire turning angle and yaw rate to increase, that is, the magnitude of the response, and the steering wheel to become sensitive.

Objectives/Problems of the Invention The objectives/problems of the present invention are to suppress the complexity of the device, reduce the response magnitude (gain) and response delay (phase) to steering wheel operations, suppress fluctuations in steering force, and improve steering performance. Our goal is to provide power steering systems used in automobiles that improve performance and safety.

Summary of the invention in terms of structure related to the object/problem: Contents of the claimed invention In relation to the above-mentioned object/problem, a power cylinder used in an automobile according to the present invention comprises a power cylinder, a pair of reaction force chambers. control valve and oil
The vehicle is equipped with a pump for steering, and the differential pressure between the reaction chambers is controlled by a differential pressure regulating valve that reduces the flow rate of pressure oil flowing between the reaction chambers as the vehicle speed increases, and The drive pressure oil flowing from the oil pump's discharge side to the control valve is controlled by a variable throttle that increases the flow rate as the vehicle speed increases, and at that time, a portion of the drive pressure oil is The oil is returned to the suction side of the oil pump by a flow regulating valve that opens and closes based on the differential pressure between the upstream and downstream sides of the variable throttle, and by adjusting the differential pressure between the reaction chambers,
By controlling the magnitude of the response to the steering wheel operation to a small value, and by changing the flow rate of the driving pressure oil supplied to the power cylinder, the delay in response to the steering wheel operation can be controlled to a small value, and the steering force can be reduced. The purpose is to suppress fluctuations.

In addition, in the power steering used in the automobile of this invention, the magnitude of the response (gain) depends on the ratio of the steering force to the yaw rate, and the delay (phase) of the response depends on the ratio between the steering force and the yaw rate. The yaw rate and phase are respectively defined.

DESCRIPTION OF EMBODIMENTS Preferred embodiments of the power steering system for use in automobiles according to the present invention will be described below with reference to the drawings.

The figure schematically shows an embodiment 10 of a power steering system for use in a motor vehicle according to the invention applied to a truck.

This power steering 10 is manufactured as a linkage type that steers a pair of front wheels (not shown), and includes a knuckle arm (not shown), a drag link (not shown), and a link lever (not shown). , compensating rod (not shown), pitman arm (not shown),
It includes a steering gear box (not shown), a steering wheel shut (steering shaft, not shown), a handle (steering wheel, not shown), and a pair of cylinder chambers 34 and 35. power cylinder 11, oil pump 12, and twin reaction chambers 4
Control valve 13 with 6.47, flow
Control valve 14, oil reservoir 15, and a pair of reaction chambers 46, 47 of its control valve 13
a reaction force adjustment passage 16 which communicates with each other, a reaction force chamber 46 thereof,
47, a differential pressure regulating valve 17 disposed in its reaction force regulating passage 16, a supply hydraulic pipe 7 between its control valve 13 and its flow control valve 14.
2, the supply side hydraulic pipe 72 on the upstream side of the variable throttle 18 is connected to the return side hydraulic pipe 7.
3, and a control valve 19 which is electrically connected to the vehicle speed sensor 21 on the input side and to the differential pressure regulating valve 17 and the variable throttle 18 on the output side, respectively. The control unit 20 inputs a signal from the vehicle speed sensor 21 to control the current flowing through the differential pressure regulating valve 17 and the variable throttle 18, and the differential pressure regulating valve 17 The reaction force chamber 4 is configured to reduce the flow rate of pressure oil flowing between the reaction force chambers 46 and 47 as the vehicle speed increases.
By controlling the differential pressure between 6 and 47, a hydraulic reaction force adapted to the vehicle speed is obtained, and the variable throttle 18 controls the driving pressure oil so that the flow rate increases in accordance with the increase in the vehicle speed. At the same time, the flow regulating valve 19 is opened and closed by the differential pressure between the upstream and downstream sides of the variable restrictor 18 to return a portion of the drive pressure oil to the suction side of the oil pump 12 to respond. It operates so that the magnitude (gain) and response delay (phase) are small.

As such, the power steering 10 consists of a link mechanism and a hydraulic circuit. - the cylinder 11 has a cylinder body in which the control valve 13 is installed and has a cylinder bore 31 opening an oil port 36.37 connected to the cylinder ports 43, 44.45 of the control valve 13; 30 and reciprocally slidably fitted within the cylinder bore 31 thereof,
A piston 32 forming a pair of cylinder chambers 34.35 in the cylinder bore 31 corresponding to and connected to the oil ports 36.37; The cylinder body 3 is composed of a piston rod 33 extending removably with both ends corresponding to the outside.
0 to its link lever, its piston rod 33
are each rotatably connected to a shaft frame (not shown).

Moreover, this power cylinder 11 has its cylinder chamber 3
4 oil port 36 to its control valve 1
3 cylinder bow) 43. Communication path 7 connected to 45
4.75 and its cylinder chamber 35 oil port 37
that control valve 13 cylinder port 4
4. A communication path 76 is provided.

In the power cylinder 11 configured in this way,
The movement of the piston 32 causes the cylinder body 30
The movement of the piston rod 33 causes a pair of front wheel axles (not shown) swingably connected to both ends of the front axle (not shown) through its link lever, drag link, and knuckle arm. (not shown) and as such the power cylinder II steers the pair of front wheels rotatably supported on the front axle.

The oil pump 12 is driven by an internal combustion engine (not shown) mounted on the truck, and its power
In order to supply pressurized oil to the cylinder 11, it is arranged in the supply hydraulic line 72 of the hydraulic circuit connecting the oil reservoir 15 to the pump port 41 of the control valve 13, and in the oil reservoir 15. The oil is sucked up and pressurized so that the amount of pressurized oil discharged is approximately proportional to the rotational speed of the internal combustion engine. Of course, the oil pump 12 is manufactured to have a similar structure to the oil pump used in existing power steering systems, and its explanation will be omitted.

The control valve 13 is configured as a hydraulic reaction type spool valve, is installed in the cylinder body 30 of the power cylinder 11, and connects the spool shaft 80 to the convensating rod.
The valves are operated by the steering wheel via the pitman arm, steering gear box, and steering shaft, and in the hydraulic circuit, the power cylinder 11 is connected to the oil pump 12 and the oil pump. It is arranged in the piping connecting the reservoir 15, that is, the supply side hydraulic piping 72, the return side hydraulic piping 73, and the communication path 74.75° 76, and controls the direction of the pressure oil discharged from the oil pump 12,
It supplies the power cylinder 11 and directs the pressure oil worked in the power cylinder 11 and returns it to the oil reservoir 15 on the suction side of the oil pump 12.

The control valve 13 has a valve body 38
and a spool 40 reciprocally slidably disposed in a spool bore 39 of the valve body 38, the spool 40 being coupled to the spool shaft 80. A compensating rod, a pitman arm, a steering gear box, and a pair of cylinder chambers of the power cylinder 11 are reciprocally slid into the spool bore 39 by the steering wheel through the steering shaft and the pair of cylinder chambers of the power cylinder 11. 34. Switch the pressure oil flowing to 35,
The switching action directs the pressure oil returned from the cylinder chamber 34,35 to the oil reservoir 15.

The valve body 38 has a spool bore 39 formed therein having a predetermined inner diameter and length, and a spool bore 39 formed therein at a predetermined distance on one side (the upper side in the figure). forming a pump port 41 and a tank port 42 connected to the spool, and spaced approximately equally apart on the other side (lower side in the figure);
3 cylinder bores connected to bore 39) 43,4
It forms 4°45.

The pump boat 41 is connected to the discharge side of the oil pump 12 via a supply hydraulic line 72, and the tank boat 42 is connected to the return side hydraulic line 73.
The cylinder boats 43, 44, 45 are further connected to the cylinder chambers 34, 35 of the power cylinder 11 via communication passages 74, 75, 76. There is.

Further, the valve body 38 has a pair of reaction boats 48 and 49 within the spool bore 39 that are used to communicate reaction chambers 46 and 47 formed on opposite sides of the spool 40 with each other. is formed.

The spool 40 has bores 50.5 opened on both end faces.
1 and reciprocally slidably disposed in the spool bore 39, and as such fitted into the spool bore 39, the bores 50, 51 are arranged within the spool bore 39 to The volumes of a pair of reaction force chambers 46 and 47 formed on both sides of the spool 40 are increased.

Also, when the spool 40 reciprocates within the spool bore 39, a pair of reaction forces supply pressure oil to either one of the reaction chambers 46, 47, depending on the sliding direction of the spool 40. It is equipped with communication boats 52 and 53.

In particular, the spool 40 is connected to the reaction force communication port 52 .
53, spool grooves 54, 55, and 56 are formed on the outer circumferential surface at predetermined intervals in the axial direction.

Of course, the reaction force chamber 46 is located in the spool groove 55, 56.
．． The reaction force communication boats 52, 53 communicating with the reaction force communication boats 52.47 are correspondingly opened, so that the reaction force communication boats 52.
53 is the spool accompanying the movement of the spool 40.
The position of the spool groove 55,56 in the bore 39 connects the cylinder boat 44,45 to the reaction chamber 46.47, and the spool groove 54 connects the pump boat 41 to the cylinder. Contact boat 43.

Further, the spool 40 extends through the valve body 38 and into the spool bore 39 such that the spool 40 is slid back and forth into the spool bore 39 in response to a steering operation. - Approximately the center of the spool (spool center) is connected to the tip of the shaft 80. Of course, the spool shaft 80 connects the rear end to the compensating rod.

The flow control valve 14 is connected in the hydraulic circuit to hydraulic piping connecting the control valve 13 to the oil pump 12 and the oil reservoir 15, ie, supply hydraulic piping 72 and return hydraulic piping 73. It is located.

The flow control valve 14 is connected to a pump boat 58 connected to the discharge side of the oil pump 12.
, the pump boat 41 of its control valve 13
A casing 57 having a control valve boat 59 connected to the side thereof and a return boat 60 connected to the suction side of the oil pump 12, and an oil disposed in the casing 57 so as to be reciprocally slidable.・The configuration includes a return control spool, which adjusts the flow rate of the drive pressure oil sent to the pump boat 58 side, sends a predetermined flow rate to the control valve boat 59 side, and also controls the drive pressure oil. Excess flow of pressure oil is returned from the return boat 60 to the oil reservoir 15 via a control valve bypass 77.

Of course, the flow control valve 14 is manufactured to have a similar structure to the flow control valve used in existing power steering systems, and a detailed explanation of its structure will be omitted.

The reaction force adjustment passage 16 connects one end to a reaction force boat 48 and the other end to a reaction force boat 49, and connects the reaction force chambers 4 to 49.
6 and 47 to each other, and its control valve 1
In response to the movement of the spool 40 at 3, it allows pressure oil to move between the reaction chambers 46, 47.

The differential pressure adjustment valve 17 is arranged in the reaction force adjustment passage 16 and adjusts the amount of pressure oil flowing between the reaction force chambers 46 and 47.
The pressure difference between the reaction chambers 46 and 47 is adjusted.

The differential pressure regulating valve 17 includes a valve body 61 having a spool chamber (not shown) and a pair of boats 62, 63 in communication with the spool chamber. The spool is arranged such that it can be slid back and forth, and the cross-sectional area of the passage within the spool chamber changes in response to the reciprocating movement of the spool.

Therefore, the flow rate of the pressure oil flowing between the boats 62, 63 is adjusted according to the reciprocating movement of the spool. In other words, the reaction chambers 46, 63 of the control valve 13 are adjusted.
The differential pressure between 47 and 47 is adjusted.

Of course, the differential pressure regulating valve 17 is connected to the pair of ports) 62.
If the flow rate of pressure oil flowing between 63 and 63 can be adjusted,
The shape is arbitrary, and for example, it is also possible to configure it into a rotary type.

The differential pressure regulating valve 17 is opened and closed by an electric actuator 64. That is, the electric actuator 64
is connected to the spool of the differential pressure regulating valve 17 by a servo motor so as to reciprocate the spool of the differential pressure regulating valve 17 to change the cross-sectional area of the passage within the spool chamber.

Of course, the electric actuator 64 can have any form as long as it is electrically connected to a control unit 20, which will be described later, and causes the spool to reciprocate by the output current from the control unit 20. For example, a stepper motor or an electromagnetic coil can be used as the electric actuator 64.

The variable diaphragm 8 is operated by an electric actuator (not shown).
The control valve 1 drives a needle (not shown) and determines the flow rate by adjusting the gap between the needle and orifice (not shown).
3 and its flow control valve 14, the oil is discharged from the oil pump 12, the flow rate is controlled by the flow control valve 14, and the oil is discharged from the control valve 1.
The drive pressure oil flowing through the pump 3 makes it possible to control the flow rate to be increased in accordance with an increase in the traveling speed of the truck, that is, the vehicle speed. Of course, the electric actuator is a solenoid coil, and the variable aperture 18 electrically connects the solenoid coil to an output circuit (not shown) of the control unit 20. The flow control valve 14 is driven by the determined output current, in other words the current controlled by the control unit 20.
The control from that oil bomb 2 through
The flow rate of the drive pressure oil flowing into the valve 3 is adjusted so that the flow rate can be increased in accordance with the increase in vehicle speed.

The flow adjustment valve 19 has a valve bore 66 and a pump boat 69 connected to one end side of the valve bore 66.
and tank boat 70 and its valve bore 6
A valve body 65 with a pressure lead boat 71 connected to the other end of the valve body 65 has a reciprocating sliding member in its valve bore 66 to communicate and disconnect its pump boat 69 and tank boat 70. a poppet 67 that can be fitted into the valve bore 66;
The pump boat 69 and the tank boat 70 are made to have a structure including a pressure regulating spring 68 disposed on the other end side of the valve bore 66 so as to be biased toward one end side. The pressure lead boat 71 is connected to the variable throttle bypass 78 and the pressure lead boat 71 connects the variable throttle 1 of the supply hydraulic line 72 with the pressure lead line 79.
It is connected to the downstream side of 8.

Its supply and return hydraulic piping 72°73
The flow regulating valve 19 disposed in the variable restrictor bypass 78 connecting the valves to each other has its poppet 67 slid back and forth within its valve bore 66 due to the differential pressure between the upstream and downstream sides of the variable restrictor 18. , so-called opening and closing, and as the poppet 67 opens and closes, the pump boat 69 is connected to the tank boat 70, and the oil pump 12 is connected to the control valve 13 via the flow control valve 14. A portion of the drive pressure oil that flows through is returned to its oil reservoir 15. In other words, this flow rate regulating valve 19 returns the oil from the upstream side of the variable throttle 18 to the oil reservoir 15 at the differential pressure between the upstream side and the downstream side of the variable throttle 18 depending on the amount of restriction of the variable throttle 18. Adjust the flow rate of the driving pressure oil.

The control unit 20 has an input side electrically connected to the vehicle speed sensor 21, and an output side electrically connected to the electric actuator 64 of the differential pressure regulating valve 17 and the solenoid coil of the variable throttle 18, respectively. , inputs a signal from the vehicle speed sensor 21, determines the output current for the differential pressure regulating valve 17 and the variable throttle 18 according to the input signal, and applies the output current to the electric actuator 64 and the solenoid. The current flows through the coil, and the differential pressure regulating valve 17 is opened and closed, and the differential pressure regulating valve 1 at that time
In step 7, the passage cross-sectional area is changed to reduce the magnitude of the response (gain), and the variable throttle 18 is opened and closed. Adjustments are made to reduce the response delay (phase) by changing the gap and cooperating with the flow rate regulating valve 19 which regulates the flow rate of the driving pressure oil returned to the oil reservoir 15.

Of course, the control unit 20 is comprised of input and output circuits, a memory circuit, an arithmetic circuit, a control circuit, and a power supply circuit, and the power supply circuit shares the truck's buffer battery (not shown).

In particular, the control unit 20 controls the reaction chamber of the control valve 13 so that, in relation to the truck, an optimum value of power cylinder pressure corresponding to the vehicle speed is generated in the power cylinder 11. The ideal value of the differential pressure between 46 and 47 is input in advance, and the vehicle speed sensor 2
1, and compares the calculated value with the optimum value to control the output current flowing to the differential pressure regulating valve 17, and control the reaction force chambers 46, 47 of the control valve 13. The power steering 10 is adapted to the vehicle speed by adjusting the passage cross-sectional area of the differential pressure regulating valve 17 so that the differential pressure between the two matches an ideal value inputted in advance.

In addition, the control unit 20 widens the gap between the needle and the orifice as the vehicle speed increases, so as to reduce the response delay (phase), and the control valve 13 increases the gap between the control valve 13 and the power cylinder. 11
The power steering 10 is adapted to the vehicle speed by increasing the flow rate of the drive pressure oil flowing to the vehicle.

In that way, the control unit 20
In this power steering system 1o, the differential pressure is adjusted so that a steering force suitable for the vehicle speed is obtained, the magnitude of the response (gain) is corrected, and the delay (phase) of the response is corrected. Controls valve 17 and variable throttle 18.

The vehicle speed sensor 21 detects the traveling speed of the trunk, and is arranged on the output shaft of a transmission (not shown) mounted on the truck.

Next, to describe the operation of the power steering 10 described above in relation to the running state of the truck, since the internal combustion engine is being operated, the oil pump 12 is driven, and the oil pump 12 is The discharged driving pressure oil is first adjusted in flow rate by the flow control valve 14, then adjusted by the variable restrictor 18, and maintained at a pressure determined by the flow HJ adjustment, and then transferred to the supply side hydraulic piping. 72 and is sent to the pump port 41 of the control valve 13, and a portion of the driving pressure oil is opened depending on the vehicle speed, or in other words, the differential pressure between the upstream side and the downstream side of the variable throttle 18. The oil is returned to the oil reservoir 15 by its flow regulating valve 19.

As shown in the figure, if the spool 40 is placed in the neutral position, the driving pressure oil sent to the pump port 41 is transferred from the tank port 42 via the return hydraulic piping 73. Oil reservoir 1
Returned to 5.

At the same time, the control unit 20 inputs a signal from the vehicle speed sensor 21 and controls the differential pressure regulating valve 1.
A system in which the output current flowing through the electric actuator 64 of 7 is controlled, and the differential pressure between the reaction force chambers 46 and 47 of the control valve 13 is adjusted according to the vehicle speed to obtain a hydraulic reaction force suitable for the vehicle speed. , is in a position to control the magnitude of the response, and also controls the output current flowing to the solenoid coil of the variable throttle 18, and changes the gap between the needle and the orifice according to the vehicle speed to match the vehicle speed. It is in a position to obtain the flow rate of the driving pressure oil, that is, to control the response delay.

Therefore, the adjustment operation of the magnitude of the response of the power steering 10 when the vehicle is traveling while the trunk is being steered will be described.

Now, if the trunk is traveling at a low speed, the control unit 20 inputs a signal from the vehicle speed sensor 21, calculates according to the input signal, and compares it with the ideal value of the differential pressure input in advance. Then, the output signal, that is, the output current is determined, and the output current is passed through the electric actuator 64 of the differential pressure regulating valve 17, so that the electric actuator 64 is driven, and in the differential pressure regulating valve 17,
the spool is slid into the spool chamber;
The passage cross-sectional area within the spool chamber is widened.

In such a state, if the spool 40 of the control valve 13 is slid in either direction into the spool bore 39 by steering, the oil The driving pressure oil discharged from the pump 12 is sent to one of the cylinder chambers 34 and 35 of the power cylinder 11 and to one of the reaction chambers 46 and 47 of the control valve 13.

For example, if the spool 40 is slid to the right in the figure, the pump port 42 will be connected to the cylinder port 44 through the spool groove 55 and the tank boat 42 will be connected to the cylinder port 44 through the spool groove 55. The driving pressure oil discharged from the oil pump 12 is sent to the cylinder chamber 35 of the power cylinder 11 via the communication passage 76, and the piston 32 is In the figure, the power cylinder 11 is slid to the right, and the driving pressure oil in the cylinder chamber 34 of the power cylinder 11 is returned to the oil reservoir 15 via the communication passage 74, 75 and the return hydraulic pipe 73.

As such, when drive pressure oil is supplied, a portion of the drive pressure oil is sent to the reaction force chamber 46 via the reaction force communication port 52 and the bore 50.

The reaction force during such steering is given by the oil pressure in the reaction force chamber 46, but as mentioned above, during low speed running, the passage cross-sectional area of the differential pressure regulating valve 17 is widened, so that The pressure oil in the reaction force chamber 46 is
6 and flows to the other reaction force chamber 47 without being extremely restricted by the differential pressure regulating valve 17.

Furthermore, when the spool 40 is slid in the above-mentioned direction, the tank boat 42 is connected to the spool groove 56, and the pressure oil in the reaction chamber 47 is passed through the return side hydraulic pipe 73. It is returned to its oil reservoir 15.

Therefore, the pressure drop due to the differential pressure regulating valve 17 becomes smaller, the pressure difference in the left and right reaction force chambers 46, 47 becomes smaller, and the pressure oil in the reaction force chamber 46 becomes larger due to the sliding movement of the spool 40. There is no resistance; in other words, steering at low speeds is performed with a small operating force. That is, the magnitude of the response, the so-called ratio of the steering force to the yaw rate, is adapted to this low-speed running and becomes small, improving running stability.

Also, if the spool 40 in the control valve 13 is slid to the left in the figure, the pump boat 41 will be connected to the spool groove 54 and the tank port 42 will be connected to the spool groove 55. The driving pressure oil discharged from the oil pump 12 is sent to the cylinder chamber 34 of the power cylinder 11 through the communication passage 74, and the piston 32 is slid to the left in the figure, and the driving pressure oil is discharged from the oil pump 12. - The driving pressure oil in the cylinder chamber 35 of the cylinder 11 is returned to the oil reservoir 15 through the communication passage 76 and the return hydraulic piping 73.

Contrary to the case described above, the pressure oil in the reaction force chamber 47 passes through the reaction force adjustment passage 16 and is sent to the reaction force chamber 46 without being extremely restricted by the differential pressure adjustment valve 17. The pressure oil in the reaction chamber 46 is returned to the oil reservoir 15 through the pore 50, the reaction communication port 52, the spool groove 55, the tank port 42, and the return hydraulic piping 73.

Therefore, as in the case described above, the pressure drop due to the differential pressure regulating valve 17 becomes smaller, the pressure difference between the left and right reaction force chambers 46 and 47 becomes smaller, and the pressure oil in the reaction force chamber 47 is reduced. There is no large resistance to sliding of the spool 40, and steering is performed with a small operating force. That is, the magnitude of the response, the so-called ratio of the steering force to the yaw rate, is adapted to this low-speed running and becomes small, improving running stability.

Furthermore, if the trunk is being driven at high speed, the control unit 20 inputs a signal from the vehicle speed sensor 21 and performs calculations according to the input signal.
The output current is determined by comparing it with the ideal value of the reaction pressure inputted in advance, and the output current is caused to flow through the electric actuator 64 of the differential pressure regulating valve 17.

Therefore, the electric actuator 64 is driven with the output current, and in the differential pressure regulating valve 17 the spool is slid into the spool chamber and the passage cross-section in the spool chamber is adapted to the vehicle speed. narrowed.

As in the case of low-speed running described above, if the spool 40 of the control valve 13 is slid to either side by steering, depending on the sliding direction of the spool 40,
The pressure oil is in the cylinder chamber 34 of the power cylinder 11.
．． 35, the piston 32 slides, and a part of the driving pressure oil is sent to either one of the reaction force chambers 46,
47, but since the cross-sectional area of the passage inside the spool chamber of the differential pressure regulating valve 17 is narrowed,
The pressure drop caused by the differential pressure regulating valve 17 increases, and the pressure difference between the left and right reaction force chambers 46 and 47 increases, and as a result, the pressure oil in one of the reaction force chambers 46 and 47 is This creates a large resistance to sliding.

As such, a relatively large operating force is required for steering during high-speed travel. That is, the magnitude of the response, the so-called
The ratio between the steering force and the yaw rate is adapted to this high-speed running and becomes small, improving running stability.

Furthermore, when the truck is parked, the traveling speed is zero, so the cross-sectional area of the passage in the differential pressure regulating valve 17 is widened to the maximum, and the mutual pressure difference between the reaction chambers 46 and 47 is reduced. becomes extremely small, and as a result, its setting is performed with extremely small operating force.

As described above, in the power steering 10, the magnitude of the response is controlled to be small in accordance with the vehicle speed.

Next, the response correction operation of the power steering 10 according to the vehicle speed of the trunk will be described.

Now, if the trunk is traveling at a low speed, the control unit 20 inputs a signal from the vehicle speed sensor 21, performs calculations according to the input signal, and determines an output signal, that is, an output current. , the output current flows through the solenoid coil of the variable aperture 18, so that in the variable aperture 18, the needle is connected to the solenoid coil.
Driven by a coil, the gap between its needle and its orifice is narrowed.

Therefore, the flow rate of the driving pressure oil flowing into the pump port 41 of the control valve 13 is reduced, and at the same time, the differential pressure between the upstream side and the downstream side of the variable throttle 18 increases, and the flow rate regulating valve 19 increases. is a drive system in which the pressure of driving pressure fluid flowing into one end of the valve bore 66 from the pump port 69 flows into the other end of the valve bore 66 from the pressure lead port 71. The pressure becomes higher than that of the hydraulic oil, and the poppet 67 is slid from one end to the other in the valve bore 66 against the pressure regulating spring 68, opening the tank boat 70 wide. A large amount of the drive pressure oil flowing into the variable throttle 18 is returned to the oil reservoir 15 via the variable throttle bypass 78 and the return hydraulic piping 73.

In such a state, if the spool 40 of the control valve 13 is slid either way into the spool bore 39 by steering, the oil The driving pressure oil discharged from the pump 12 is supplied to either one of the cylinder chambers 34, 35 of the power cylinder 11, and at the same time, a portion of the driving pressure oil is transferred to the reaction force communication port) 52. 53
It is also supplied to either one of the reaction force chambers 46, 47 of the control valve 13.

At this time, the flow rate of the drive pressure oil is adjusted to the variable throttle 18.
Since the cylinder chamber 34 is reduced by
．． The flow rate of the driving pressure oil supplied to either one of the pistons 35 is also reduced, and the movement of the piston 32 is slowed down to adapt to the low-speed running, in other words, response delay, so-called
The phase between the steering force and the yaw rate is adapted to the low speed running and reduced, improving maneuverability.

Contrary to the above, if the spool 4σ of the control valve 13 is slid into the spool bore 39 either way by steering, the drive pressure oil is transferred to the cylinder chamber of the power cylinder 11. 34, 35 in a small amount, and at the same time a portion of the drive pressure oil is supplied to the reaction chamber 46 of the control valve 13,
47.

At this time, the movement of the piston 32 is adapted to the low-speed running and slows down, in other words, the response is delayed, so-called, and the phase between the steering force and the yaw rate is adapted to the low-speed running and is reduced. and improves maneuverability.

Furthermore, if the truck is traveling at high speed, the control unit 20 inputs a signal from the vehicle speed sensor 21 and performs calculations according to the input signal.
Since the output signal, that is, the output current is determined, and the output current is passed through the solenoid coil of the variable aperture 18,
In the variable aperture 18, the needle is driven by the solenoid coil to widen the gap between the needle and the orifice.

Therefore, the flow rate of the driving pressure oil flowing into the pump boat 41 of the control valve 13 is increased, and at the same time, the differential pressure between the upstream side and the downstream side of the variable throttle 18 is reduced, and the flow rate adjustment valve 19 is is a drive system in which the pressure of driving pressure fluid flowing into one end of the valve bore 66 from the pump port 69 flows into the other end of the valve bore 66 from the pressure lead port 71. As the oil pressure approaches, the poppet 67 is slid into the valve bore 66 from one end to the other by its pressure regulating spring 68, causing the tank bow 1-70 to narrow (
The drive pressure oil that is opened and flows through the variable throttle 18 is returned in small quantities to the oil reservoir 15 via the variable throttle bypass 78 and the return hydraulic line 73.

In such a state, if the spool 40 of the control valve 13 is slid either way into the spool bore 39 by steering, the oil The driving pressure oil discharged from the pump 12 is supplied to either one of the cylinder chambers 34, 35 of the power cylinder 11, and at the same time, a portion of the driving pressure oil is transferred to the reaction force communication port) 52. 53
It is also supplied to either one of the reaction force chambers 46, 47 of the control valve 13.

At this time, since the flow rate of the drive pressure oil is increased by the variable throttle 18, the cylinder chamber 34.35
The flow rate of the driving pressure oil supplied to one of the two is also increased, and the movement of the piston 32 is adapted to the high-speed running and becomes faster.In other words, the response delay, so-called, between the steering force and the yaw rate is The phase is reduced to suit its high speed running and improves maneuverability.

Contrary to the above, if the spool of the control valve 13 is slid either way into the spool bore 39 by steering, the drive pressure oil is transferred to the cylinder chamber 34 of the power cylinder 11. .35, and at the same time, a portion of the drive pressure oil is also supplied to the other of the reaction chambers 46, 47 of the control valve 13.

At this time, the movement of the piston 32 is adapted to the high-speed running and becomes faster. In other words, the response delay, so-called phase between the steering force and the yaw rate, is adapted to the high-speed running and is reduced. , maneuverability is improved.

Of course, the operation of the power steering 10 with respect to the vehicle speed described above is the same as that of the power steering 10 described above.
This is done simultaneously with the adjustment of the magnitude of the response.

Although the power steering 10 described above was manufactured as a linkage type, this power steering 10 can be manufactured in various types such as an integral type and a semi-integral type.

Conveniences and Benefits of the Invention From the foregoing, it can be seen that the power steering and differential steering systems used in the automobile of this invention are superior to the power steering and differential steering systems used in automobiles that have already been proposed and used. The steering is controlled
The differential pressure between the pair of reaction chambers of the valve is controlled by a differential pressure regulating valve that reduces the flow rate of pressure oil flowing between the reaction chambers as the vehicle speed increases, and The drive pressure oil that flows from the control valve to the control valve is controlled by a variable throttle that increases the flow rate as the vehicle speed increases, and at that time, a portion of the drive pressure oil flows into the upstream and downstream sides of the variable throttle. The oil is returned to the suction side of the oil pump by a flow regulating valve that opens and closes depending on the differential pressure between the two. The magnitude of the response to the operation is controlled to be small, that is, as the vehicle speed increases, the differential pressure between the reaction force chambers is increased,
By increasing the steering force and making the steering wheel heavier, the magnitude of the response (in other words, the ratio between the steering force and the yaw rate) is reduced, driving stability is improved, and the power and
By changing the flow rate of the driving pressure oil supplied to the cylinder, the delay in response to the steering wheel operation is controlled to be small.In other words, as the vehicle speed increases, the driving pressure supplied to the power cylinder increases. By increasing the flow rate of oil and increasing the flow rate of driving pressure oil, the rise of hydraulic pressure is made faster and the response is delayed, in other words,
The phase with the yaw rate outside the steering force is reduced, improving maneuverability, and in addition, fluctuations in the steering force are suppressed, the neutral state of the steering wheel becomes clearer, and the entire device becomes structurally more complex. is suppressed, making it extremely useful for automobiles.

As for the relationship between the invention and the specific examples, from the specific examples of the present invention described with reference to the drawings, various design modifications will be apparent to those who have ordinary knowledge in the technical field to which this invention pertains. Further, the contents of this invention are essential to the establishment of the invention for accomplishing the task of the invention, and are derived from the technical essence of the invention which is the nature of the invention. and can be easily replaced with a form that is objectively recognized as incorporating it.

[Brief explanation of the drawing]

The figure is a schematic diagram showing a specific example of the power steering system used in an automobile according to the present invention applied to a truck. 11... Power cylinder, 12... Oil pump, 13... Control valve, 14... Flow control valve, 15... Oil reservoir, 16... Reaction force adjustment passage , 17... Differential pressure regulating valve,
18... Variable throttle, 19... Flow rate adjustment valve, 20...
- Control unit, 21...Vehicle speed sensor, 7
2... Supply side hydraulic piping, 73... Return side hydraulic piping,
78...Variable aperture bypass.

Claims (1)

[Claims] In a steering vehicle equipped with a power cylinder, a control valve having a pair of reaction force chambers, and an oil pump, the differential pressure between the reaction force chambers increases as the vehicle speed increases. It is controlled by a differential pressure regulating valve that reduces the flow rate of pressure oil flowing between reaction chambers, and the control valve is controlled from the discharge side of the oil pump.
The drive pressure oil flowing into the valve is controlled by a variable throttle that increases the flow rate as the vehicle speed increases, and at that time, a portion of the drive pressure oil is controlled by the differential pressure between the upstream and downstream sides of the variable throttle. A power cylinder used in an automobile, characterized in that the oil is returned to the suction side of the oil pump by a flow rate regulating valve that is opened and closed at the same time.