JPH0790787B2 - Power steering used in vehicles - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to power steering for use in vehicles that are speed and load sensitive and have improved responsiveness.

BACKGROUND ART In a vehicle of this type, for example, a large vehicle, since the steering shaft axial load is large, the power steering has a hydraulic pump and a power cylinder that are large in size. The steering force required during extremely low speed driving has been secured.

However, on the other hand, the load on the engine that drives the hydraulic pump becomes extremely large, and even during high-speed traveling where a large supply capacity of the hydraulic pump is not required, the engine is heavily loaded and the fuel consumption rate is reduced. Tended to

Further, Japanese Utility Model Laid-Open No. 59-110270 discloses a hydraulic circuit of a power steering device in which a load sensing valve is arranged between a pair of power cylinders and a control valve. In the hydraulic circuit, when the oil pressure is higher than a predetermined value, the pressure oil is supplied to both power cylinders by the load sensing valve to generate steering force in both power cylinders. Pressure oil is supplied only to one power cylinder by its load sensing valve, and oil that causes a shortage in the other power cylinder is supplied from that one power cylinder to that one power cylinder.
Since the steering force is generated only in the cylinder, even if a fast steering operation near neutral can be performed, the other power cylinder does not idle very lightly during normal driving, resulting in reduced engine load. However, the power generated by the engine tends to be wasted.

Furthermore, with such a power steering, the steering force is light, but the steering wheel operating angle (steering wheel lock-to-lock) is large, so the driver is fatigued by the steering wheel operation, and gears are tried to reduce the fatigue. When the ratio is reduced and the steering wheel operating angle is reduced,
When the vehicle was traveling at high speed, the reaction of the vehicle to the operation of the steering wheel, that is, the steering wheel became too sensitive.

An object of the present invention is to suppress an increase in a pressure receiving area in a hydraulic pump or a power cylinder, suppress wasteful consumption of engine-generated power, and improve a fuel consumption rate of an engine. Steering is performed by reducing the engine load to suppress wasteful consumption of engine generated power and improving the fuel consumption rate of the engine, and also by appropriately changing the steering force according to the vehicle stop, running and load. It reduces the fatigue caused by, especially, the stationary steering force at the time of stopping and the steering force at the time of low speed traveling are lightened, and the steering wheel operating angle is made small to facilitate the driving operation. It is to provide the power steering used for the vehicle that suppresses the occurrence of.

SUMMARY OF THE INVENTION AND CONTENTS OF CLAIMED INVENTION In connection with the above problems, a power steering used in a vehicle of the present invention steers a pair of wheel shafts swingably connected to both ends of an axle. Main booster, an auxiliary booster that supplements the steering force of the main booster, a hydraulic pump whose pump discharge rate is set to a value at which the steering speed is less than 5 to 10 rad / sec, and its main booster A main hydraulic pipe that connects to the pump, an auxiliary hydraulic pipe that connects the auxiliary booster to the main booster, and a control that is arranged on the main hydraulic pipe and that directionally controls the pressure oil supplied from the hydraulic pump to the main booster.・ Valve and valve body, which has a valve bore and a pair of load sensing chambers open at both ends of the valve bore. From a spool that is slidable back and forth to partition the load sensing chamber from the valve bore, and a pair of set pressure springs that are placed in the load sensing chamber and press the opposite ends of the spool correspondingly. It is configured and arranged in its auxiliary hydraulic piping, which guides the hydraulic pressure of its main booster to its load sensing chamber and is switched, and then supplies pressure oil from its main booster to its auxiliary booster to its main booster. A load sensing valve that moves the auxiliary booster synchronously or short-circuits the cylinder chambers of the auxiliary booster while shutting off the pressure oil from the main booster to the auxiliary booster to move the auxiliary booster idly, and a gear The ratio is set to 5 to 10 and the movement of the steering wheel is controlled by And a steering gear box that enables transmission to a valve, and when the oil pressure of the main booster is low, the main booster port is closed and the auxiliary booster port is closed to each other at the load sensing valve. Shorted to the tank port and then the auxiliary booster is idled to move only the main booster,
Also, when the hydraulic pressure of the main booster becomes high, the main booster port is connected to the auxiliary booster port in the load sensing valve, and the auxiliary booster is moved synchronously with the main booster, The booster's steering force is complemented, and the steering gear box's gear ratio can be set to a small value to reduce the steering wheel operating angle, especially when the vehicle is traveling at high speeds, its steering wheel becomes sensitive. It is about suppressing this.

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

1 to 3 show a specific example 10 of the power steering used in the vehicle of the present invention applied to the front two-axle truck 100.

This power steering 10 is the front two-axis truck
In 100, a pair of front wheel axles 101 and a pair of front and rear wheels that are swingably connected to both ends of a front axle (not shown) and front and rear axles (not shown) and that change a steering angle in conjunction with each other Steering wheel axle 102.

The power steering 10 includes a main booster 11 that steers the frontmost wheel shaft 101, an auxiliary booster 12 connected to the front and rear wheel shafts 102 so as to supplement the steering force of the main booster 11, and a hydraulic pump 13. And main hydraulic pipes 14 and 15 connecting the main booster 11 to the hydraulic pump 13, and auxiliary hydraulic pipes connecting the auxiliary booster 12 to the main booster 11.
16,17,18, the control valve 19 arranged on the main hydraulic pipes 14,15, the load sensing valve 20 arranged on the auxiliary hydraulic pipes 16,17,18, and the oil reservoir 21. , Steering wheel 22, steering shaft 23, steering gear box 24,
It includes a pitman arm 25, a compensating rod 26 and an input shaft 27, and its hydraulic pump 13 has a steering speed of 5-10 radians /
The pump discharge rate is set so that it can be filled in less than a second, and the steering gear box 24
The ratio is set to 5 to 10 to reduce the steering wheel operating angle (steering wheel lock-to-lock) and accordingly the steering force required as the steering wheel 22 becomes heavier, The valve 20 is opened so that the auxiliary booster 12 is interlocked with the main booster 11 to supplement the auxiliary booster 12, and the truck 100 is stopped or driven at a low speed.
When the load exceeds a predetermined value, the load sensing valve 20 is opened, the auxiliary booster 12 is linked to the main booster 11, the steering force is supplemented to the auxiliary booster 12, and the steering force is reduced, Further, when the truck 100 is driven under the following conditions, the load sensing valve 20 is closed, the auxiliary booster 12 is made to idle, and only the main booster 11 is moved, so that the steering force is increased. Make it heavier and prevent its steering wheel 22 from becoming hypersensitive.

The main booster 11 is a hydraulic cylinder, and the cylinder 30 and
A piston 31 fitted in the cylinder 30 so as to be reciprocally slidable and partitioning the inside of the cylinder 30 into cylinder chambers 33 and 34.
And a piston rod 32 whose one end is fixed to its piston 31 and whose other end can be taken in and out of the cylinder 30, and the other end is pivotally connected to the chassis, and the control valve is attached to the body of the cylinder 30. Manufactured in a structure containing 19. Of course, in the cylinder 30, cylinder interlock ports 35 and 36 connected to the auxiliary booster 12 and oil ports 37 and 38 connected to the control valve 19 correspond to the cylinder chambers 33 and 34. It has been opened.

The main booster 11 also pivotally connects its cylinder 30 to an idle arm 90 for its front wheel axle 101, and an idle arm 92 for the front and rear wheel axles 102.
To a relay rod 94.

Of course, the front idler arm 90 has its upper end rotatably connected to its chassis, and its lower end rotatably connected to the drag link 91, and its front drag link 91 has its frontmost wheel shaft. Since it is rotatably connected to the knuckle arm (not shown) of the knuckle (not shown) that rotatably connects 101 to the front axle, the main booster 11 causes the front idle arm 90 to The pivot connection point at the upper end is used as a fulcrum to rotate the truck 100 in the front-rear direction with respect to the chassis, and the frontmost wheel shaft 101, that is, the frontmost wheel 103 rotatably supported by the frontmost wheel shaft 101. Change the corner.

The knuckle with its front wheel axle 101 and its rotatably connected to its front axle is, of course, similar to the knuckle used in existing front twin-axle trucks: knuckle arm and tie rod.・ Arm (not shown)
Is formed in a substantially L shape and is rotatably connected to both ends of the frontmost axle via king pins (not shown).

A tie rod (not shown) is rotatably connected between the tie rod arms of the pair of knuckles rotatably connected to both ends of the front axle.

On the other hand, the rear idle arm 92 has its upper end rotatably connected to its chassis and its lower end rotatably connected to a drag link 93, and its rear drag link 93 has its front As in the case of the idle arm 90, the front and rear wheel shafts 102 are rotatably connected to the knuckle arm (not shown) of the knuckle (not shown) that rotatably connects the front and rear axles. Idol·
Through its arm 90 and relay rod 94, its main booster 11 causes its rear idle arm 92 to rotate in its anteroposterior direction of its truck 100 with respect to its chassis, with its pivot connection point at its upper end as a fulcrum. The steering angle of the front and rear wheel shafts 102, that is, the front and rear wheels 104 rotatably supported by the front and rear wheel shafts 102 is changed.

The knuckle, like the knuckle for the frontmost wheel axle 101 described above, is also configured in a substantially L shape with a knuckle arm and a tie rod arm (not shown), and is provided at both ends of the front and rear axles. Each is rotatably connected via a king pin (not shown).

A tie rod (not shown) is rotatably connected between the tie rod arms of the pair of knuckles rotatably connected to both ends of the front and rear axles.

Therefore, its main booster 11 is driven and its front and rear idle arms 90, 92 are driven by its relay rod 94.
Driven by, its front and rear drag links
If it is swung back and forth with respect to the chassis via 91,93, its front and rear knuckles are rotated around the corresponding front axle and front and rear axle king pins and its front wheels are rotated. Shaft 101, and front and rear wheel shafts 102,
That is, the front wheels 103 and the front and rear wheels 104 are steered synchronously.

The auxiliary booster 12 is connected to the front and rear wheel shafts 102 side of the front and rear axles so as to supplement the steering force by the main booster 11, and is transmitted from the main booster 11 with the operation of the load sensing valve 20. With pressurized oil, that is,
It is configured to be driven by the pressure oil sent from the hydraulic pump 13 via the control valve 19 and the main booster 11, and to be linked to the main booster 11.

The auxiliary booster 12 is a hydraulic cylinder similar to the main booster 11, and is fitted into the cylinder 42 and the cylinder 42 so as to be reciprocally slidable, and the piston 43 that partitions the inside of the cylinder 42 into the cylinder chambers 45 and 46. And one end of the piston 4
It is composed of a piston rod 44 which is fixed to 3 and whose other end can be put in and taken out from the cylinder 42. Of course, the cylinder 42 has oil connected to the cylinder interlock ports 35 and 36 of the main booster 11.
Ports 47 and 48 are opened corresponding to the cylinder chambers 45 and 46.

The auxiliary booster 12 also has its cylinder 42 pivotally connected to its idle arm 92 and the other end of its piston rod 44 to its chassis.

Therefore, if the auxiliary booster 12 is driven and the rear idle arm 92 is swung back and forth with respect to the chassis via the rear drag link 93, the knuckle will move to the front and rear axle king pins. It is rotated around and the front and rear wheel shafts 102, that is, the front and rear wheels 104 are steered. Of course, at that time, the steering force of the auxiliary booster 12 is transmitted through the relay rod 94 to the front idle arm.
90, which swings its idle arm 90 forwards and backwards with respect to its chassis via its front drag link 91 and rotates its front knuckle around its front axle king pin. Let the front wheel axle 101,
That is, the frontmost wheel 103 is steered.

As such, its auxiliary booster 12 is its main booster.
The steering force of 11 is supplemented synchronously.

The hydraulic pump 13 is driven by an engine (not shown) mounted on the truck 100 to generate hydraulic pressure for moving the main and auxiliary boosters 11 and 12, and the pump discharge amount changes the steering speed. It is set to a value less than 5 to 10 radians / second. So that this hydraulic pump
In 13, the pump discharge amount is set as small as possible to prevent the steering wheel 22, that is, the steering wheel, from becoming hypersensitive. Especially in a normal hydraulic pump,
The discharge amount of the hydraulic pump 13 is set so small as compared with the discharge amount of the pump set to the flow rate corresponding to the steering speed of the steering wheel of 12 to 18 rad / sec. This is advantageous because the sensitivity of the steering wheel when the truck 100 runs at high speed is suppressed. Of course, the discharge rate V (liter / second) of the hydraulic pump and the handle operating speed N
The relationship with (radian / second) is It is in. Here, L is the power of the lead, that is, as the steering shaft is rotated once.
The amount that the piston of the cylinder moves (cm), and
A is the pressure receiving area (cm ² ) of the piston.

The main hydraulic pipes 14 and 15 connect the main booster 11, the hydraulic pump 13, the control valve 19, and the oil reservoir 12 to the main hydraulic circuit.
Is a supply-side hydraulic pipe, which connects the hydraulic pump 13 to the control valve 19 connected to the main booster 11 by a communication passage 39, 40, 41 forming a part of the main hydraulic pipe 14. , Its oil reservoir to its hydraulic pump 13
21 connected, sent from its hydraulic pump 13, and
The pressure oil whose direction is controlled by the control valve 19 can be supplied to the main booster 11.

On the other hand, the main hydraulic pipe 15 is a return hydraulic pipe,
The control valve 19 to the oil reservoir 21
From its main booster 11 to its oil reservoir
Return pressure oil to 21.

The auxiliary hydraulic pipes 16, 17, 18 connect the auxiliary booster 12 to the main booster 11 to form an auxiliary hydraulic circuit.The auxiliary booster 12 is linked to the main booster 11 and The auxiliary booster 12 is separated from the main booster 11, and the auxiliary booster 12 is provided with its load sensing valve 20 that drives only the main booster 11 in a lost motion (lost motion).

The auxiliary hydraulic pipes 16 and 17 are connected to the cylinder interlock port 3 which is opened in the cylinder 30 of the main booster 11.
5,36 and the oil ports 47,48 opened in the cylinder 42 of the auxiliary booster 12 and the auxiliary booster 1
When 2 is linked to its main booster 11, it is a left-turn and right-turn hydraulic pipe that synchronizes its auxiliary booster 12 with its main booster 11.

Further, the auxiliary hydraulic pipe 18 is connected to the tank port 76 of the load sensing valve 20 and the return side hydraulic pipe.
15 and its auxiliary booster 12 and its oil
Return the pressure oil to the reservoir 21.

Therefore, its auxiliary hydraulic line 16,17, so connected and having its load sensing valve 20 located therein,
18 is supplied from the hydraulic pump 13, and the direction and the flow rate of which are controlled by the control valve 19, and the pressure oil supplied to the main booster 11 is supplied to the auxiliary booster 18.
12 and simultaneously return pressure oil from its auxiliary booster 12 to its oil reservoir 21 to enable the auxiliary booster 12 to be driven synchronously with its main booster 11 and also to feed the auxiliary booster 12 to its oil.・ Connect to the reservoir 21,
Pressure oil is returned from the auxiliary booster 12 to the oil reservoir 21 to enable lost motion in the auxiliary booster 12.

The control valve 19 is incorporated in the cylinder 30 and the body of the main booster 11, and is configured to be operated by a steering wheel 22. Of course,
The control valve 19 is arranged in the main hydraulic circuit in the main hydraulic piping 14, 15 connecting the hydraulic pump 13 and the oil reservoir 21 to the main booster 11 and the communication passages 39, 40, 41, The direction of the pressure oil sent from the hydraulic pump 13 is supplied to the main booster 11, and the direction of the pressure oil worked by the main booster 11 is controlled, and the oil reservoir on the suction side of the hydraulic pump 13 is controlled.
The pressure oil is returned to 21, and the pressure oil sent from the hydraulic pump 13 is passed through the main booster 11 to the auxiliary booster.
Supply to 12.

The control valve 19 includes a valve body 49 having a valve bore 50, as understood from FIG.
It is composed of a spool 51 arranged in the valve bore 50 so as to be reciprocally slidable.

The valve body 49 is a cylinder of the main booster 11.
Pump port 5 integrated into the body of 30 and opened into its valve bore 50 in place
2, cylinder port 53,54,55 and tank port 56
Is equipped with.

The pump port 52 and the tank port 56 have ring grooves 57 and 58 formed in the opening on the inner peripheral surface of the valve bore 50.
Are formed respectively.

In addition, the valve body 49 is
Vent ports 59 and 60 that were communicated to the
Both ends of the bore 50 are opened.

With the spool 51 in the neutral position, the link grooves 57, 5 of the pump port 52 and the tank port 56 are provided.
8, the spool grooves 61, 62, 63 located in the cylinder ports 53, 54, 55 are formed on the outer peripheral surface, and the spool grooves 61, 62, 63 have the spool 51 with the valve Boa
Pump port 52 as it slides back and forth in 50
To the cylinder ports 53, 54, 55, and the cylinder ports 53, 54, 55 to the tank port 56.

The spool 51 also has a pin bore at the center in the axial direction.
64 is formed, and the tip end of the input shaft 27 extending through the valve body 49 is fitted.

In the control valve 19 manufactured in such a valve structure, the pressure oil discharged from the hydraulic pump 13 is transferred to the cylinder chambers 33 and 34 of the main booster 11 and the auxiliary booster 1
In order to supply the two cylinder chambers 45,46, its pump port 52 is connected in its main hydraulic line 14 to the outlet of its hydraulic pump 13, and its cylinder ports 53,5
4,55 are connected by their communication passages 39,40,41 to the oil ports 37,38 of their main booster 11, and their tank port 56 is further connected by their main hydraulic line 15 to their oil reservoir 21.
It is connected to the. Of course, this control valve 19
Via its main booster 11 its auxiliary booster 12 is connected to its main booster 11 and oil reservoir 21 by its auxiliary hydraulic lines 16,17,18.
Supply pressure oil to 12.

Further, since the control valve 19 is operated by the steering wheel 22, the steering shaft 23 having the steering wheel 22 attached is connected to the input shaft 27 and the steering shaft 23. Steering gear box 24, a pitman arm 25 fixed to a sector shaft 28 of the steering gear box 24, and a compensating rod 26 connecting the pitman arm 25 to its input shaft 27. And the movement of the steering wheel 22 is transmitted to the input shaft 27, and the steering input by the steering wheel 22 causes the spool 51 to slide back and forth in the valve bore 50. I am trying.

The load sensing valve 20 is arranged in the auxiliary hydraulic pipes 16, 17, 18 and is manufactured in the structure shown in FIGS. 1 and 2, and the load of the truck 100, that is, the pressure of the main booster 11 thereof. It opens and closes according to the size of oil.

The load sensing valve 20 has a valve bore 66 and a pair of load sensing chambers 67 and 68 opened at both ends of the valve bore 66, as understood from FIGS. 1 and 2. In the valve body 65, the spool 69 that is reciprocally slidably disposed in the valve bore 66 and partitions the load sensing chamber 67, 68 from the valve bore 66, and in the load sensing chamber 67, 68. A pair of set pressure springs 70, 71 arranged to push correspondingly both end surfaces of the spool 69 are arranged in the auxiliary hydraulic pipes 16, 17, and the hydraulic pressure of the main booster 11 is set in the load sensing chamber 67. , 68 to switch operation, and from its main booster 11 to its auxiliary booster 12
Supply pressure oil to its main booster 11 and its auxiliary booster
The main booster 1 of the auxiliary booster 12 is moved synchronously or the cylinder chambers 45 and 46 of the auxiliary booster 12 are short-circuited to each other.
It is about to shut off the pressure oil from 1 to the auxiliary booster 12 and make the auxiliary booster 12 lose motion.

The valve body 65 internally forms the valve bore 66 and a pair of load sensing chambers 67, 68 connected to both ends of the valve bore 66, and at a predetermined position, the valve bore 66 is formed in the valve bore 66. It has a pair of open main booster ports 72,73, a pair of auxiliary booster ports 74,75, and a tank port 76, and also has a pair of pressure leads open to its load sensing chambers 67,68. It has ports 77 and 78.

As such, this valve body 65 with its main booster ports 72,73, auxiliary booster ports 74,75, tank ports 76, and pressure reed ports 77,78.
Its main booster port 7 with its auxiliary hydraulic piping 16,17
2,73 its main booster 11 cylinder interlock
Ports 35,36 and also its auxiliary hydraulic lines 16,17 with its auxiliary booster ports 74,75 with its auxiliary booster 12
Oil ports 47, 48, and its auxiliary hydraulic line 18 connects its tank port 76 to its main hydraulic line 15 to allow pressurized oil to return to its oil reservoir 21 and its spool 69. As the hydraulic pressure of its main booster 11 slides into its valve bore 66, its auxiliary booster 12
Cylinder chambers 45, 46 of the main booster 11 cylinder chamber 33,
Cylinder chamber 3 of its main booster 11
3,34 pressure oil can be selectively supplied to the cylinder chambers 45,46 of the auxiliary booster 12, and at the same time, pressure oil in the cylinder chambers 45,46 of the auxiliary booster 12 can be selectively supplied to the oil reservoir 21. I am trying to get back to you.

Further, in this valve body 65, the pressure lead ports 77, 78 connect the pressure lead pipes 79, 80 branched from the auxiliary hydraulic pipes 16, 17 on the main booster 11 side, and The load sensing chambers 67, 68 are connected to the cylinder chambers 33, 34 of the main booster 11 by pipes 79, 80, respectively, and the cylinder chambers 33, 34 of the main booster 11 are connected.
The pressure oil of the above is guided to the corresponding load sensing chambers 67 and 68.

The spool 69 has pressure-receiving surfaces 81 and 82 on both end surfaces, and receives the hydraulic pressure of the load sensing chambers 67 and 68 on the corresponding pressure-receiving surfaces 81 and 82, and slides back and forth on the valve bore 66. It is movably fitted.

The spool 69 also moves its main booster port 72,73 to its auxiliary booster port 74,74 depending on its movement.
At the same time, lands 83, 84, 85 are formed on the outer peripheral surface at predetermined intervals so that the auxiliary booster ports 74, 75 are switched and connected to the tank port 76.

The pair of set pressure springs 70, 71 are coil springs, are arranged in the load sensing chambers 67, 68, and press both end surfaces of the spool 69, that is, the pressure receiving surfaces 81, 82.

Especially, the set pressure springs 70 and 71 are
The seats 86 and 87 are respectively interposed and pushed against the pressure receiving surfaces 81 and 82 of the spool 69, and also function as a neutral spring of the spool 69. Of course, the spring seats 86, 87 are perforated so that the pressure oil in the load sensing chambers 67, 68 acts on the pressure receiving surfaces 81, 82 of the spool 69.

The steering gear box 24 has a gear ratio of 5 to 10 while the steering gear box has a gear ratio of 15 to 30, and the steering wheel 22 The movement of the can be transmitted to the control valve 19.

As such, this steering gear box 24
Reduce the gear ratio, reduce the steering wheel operating angle,
The handle is easy to operate. Of course, with such a smaller gear ratio, the steering wheel, that is, the steering wheel 22, becomes heavier, which is fully compensated by the main booster 11 and the auxiliary booster 12.

Next, the operation of the power steering 10 described above will be described in correspondence with the traveling state of the front biaxial truck 100.
Since the diesel engine is operating, the hydraulic pump 13 is driven, and the pressure oil discharged from the hydraulic pump 13 flows through the main hydraulic pipe 14 to the pump port 52 of the control valve 19. Sent to.

The pressure oil sent to the pump port 52 is the spool
If 51 is in the neutral position shown in FIG.
It flows from its pump port 52 to its tank port 56 and is returned to its oil reservoir 21 in its main hydraulic line 15.

As such, the pressure oil sent from the hydraulic pump 13 is transferred to the oil reservoir 21 by the control valve 19.
Cylinder chamber 33,3 of the main booster 11
There is no pressure difference between the pressure oils in 4 and when the pressure oils are guided to the load sensing chambers 67 and 68 by the auxiliary hydraulic pipes 16 and 17 and the pressure lead pipes 79 and 80, The spool 69 at the sensing valve 20
Is held in its valve bore 66 neutral position by its pair of set pressure springs 70, 71, its main booster ports 72, 73 being closed by its spool 69, as shown in FIG. And that auxiliary booster port
74,75 are also shorted and contacted to its tank port 76.

Therefore, the auxiliary booster 12 is separated from the main booster 11, and the auxiliary booster 12 is put in the lost motion state.

Therefore, a case will be described in which the truck 100 is set aside in a state where it is loaded with a load and stopped, or when the truck 100 is moved sideways and turned back at an extremely low speed.

Now, the steering wheel 22 is operated for its stationary steering, width-shifting and turning, and the operating force of the steering wheel 22 is applied to the steering shaft 2.
3, the steering gear box 24, the pitman arm 25, and the compensating rod 26, is transmitted to its input shaft 27, and at its control valve 19, its spool 51 is caused by its input shaft 27. When slid into either side of the valve bore 50, the control valve 19
, The pump port 52 is connected to either one of the cylinder ports 53, 54, and as a result, the pressure oil sent from the hydraulic pump 13 is supplied to one of the communication passages 39, 40, 41. The flow is supplied to either one of the cylinder chambers 33, 34 of the corresponding cylinder 30 of the main booster 11, and at that time, in the main booster 11, corresponding to the loaded weight of the truck 100, the front wheels 103 and Since the hydraulic pressure is gradually increased so that the steering force for the front and rear wheels 104 is generated and exceeds a predetermined pressure value, the cylinder chamber of the main booster 11 is
At 33 and 34, a pressure difference occurs in the pressure oil, and accordingly, also at the load sensing valve 20, the pressure oil in the cylinder chambers 33 and 34 of the main booster 11 is transferred to the auxiliary hydraulic pipes 16, 17 and A pressure difference is generated between the load sensing chambers 67, 68 led by the pressure lead pipes 79, 80, and the spool 69 thereof has a cylinder chamber 33, 34 of the main booster 11 as shown in FIG. Corresponding to that valve bore 6
Sliding in either side of 6

As such, when the spool 69 is slid into the valve bore 66, one of the main booster ports 72, 73 of the load sensing valve 20 is
Corresponding to the cylinder chambers 33, 34 of the main booster 11 is communicated with either of the auxiliary booster ports 74, 75, the other of the main booster ports 72, 73 is closed, and The other of the auxiliary booster ports 74, 75 is connected to its tank port 76.

As such, as a result of the load sensing valve 20 being switched, the cylinder chamber 3 of the main booster 11 is
The pressure oil of either one of 3, 34 is supplied to one of the cylinder chambers 45, 46 of the auxiliary booster 12.

And at that time, the cylinder chamber 3 of the main booster 11
The pressure oil on either side of 3, 34 is the control valve 19
Flow through the main hydraulic line 15 to the oil reservoir 21 and the pressure oil in either of the cylinder chambers 45, 46 of the auxiliary booster 12 is transferred to the oil by the load sensing valve 20. Flowing to the auxiliary hydraulic pipe 18,
It is returned to the oil reservoir 21.

Therefore, the main booster 11 is driven by the pressure oil from the hydraulic pump 13, and the auxiliary booster 12 is synchronously driven by the pressure oil from the main booster 11, and its front wheel is
The 103 and the front and rear wheels 104 are steered synchronously, and the stationary operation, the width adjustment, and the turning operation are smoothly performed with an appropriate operating force, that is, an extremely small operating force. So-called so-called stationary cutting, width-shifting, and turning are performed lightly.

Further, even when the truck 100 travels at a low speed, the main and auxiliary boosters 11 and 12 in the pressure oil sent from the hydraulic pump 13 are synchronously driven and steering is performed in the same manner as described above. It is possible with extremely small operating force.

Next, a case will be described in which the truck 100 is raised from a slight speed and normally travels.

When the steering wheel 22 is operated in the normal traveling state, the operating force of the steering wheel 22 is transmitted to the input shaft 27 and the control valve 19 is operated in the same manner as in the case described above. , When the spool 51 is slid into either one of the valve bores 50, at the control valve 19,
The pump port 52 is communicated with either one of the cylinder ports 53, 54, and as a result, the pressure oil delivered from the hydraulic pump 13 flows into one of the communication passages 39, 40, 41. , And is supplied to either one of the cylinder chambers 33 and 34 of the cylinder 30 of the corresponding main booster 11.

In this case, since the front wheels 103 and the front and rear wheels 104 are placed in a state where they can be steered lightly, the main booster 11 has a predetermined hydraulic pressure for generating steering force for the front wheels 103 and the front and rear wheels 104. Since it is lower than the pressure value, in the cylinder chambers 33, 34 of the main booster 11,
Although there is a pressure difference in the pressure oil, the cylinder chamber 3 of the main booster 11 of the load sensing valve 20
At the pressure differential between its load sensing chambers 67,68, which led 3,34 of pressure oil through its auxiliary hydraulic pipes 16,17 and pressure lead pipes 79,80, its spool 69 would fit in its valve bore 66. Not sliding, as shown in FIG. 1, the pair of set pressure springs 70, 71 causes the valve bore 66 to
Held in its neutral position within its main booster port 72,7
3 is closed on its spool 69 and its auxiliary booster ports 74,75 are connected to its tank port 76. As a result, the pressure oil of the main booster 11 is no longer supplied to the auxiliary booster 12. Meanwhile, its auxiliary booster
12 is also connected to its oil reservoir 21 with its cylinder chambers 45, 46 shorted together.

In this way, the pressure oil sent from the hydraulic pump 13 is supplied to the main booster 11, but the pressure oil of the main booster 11 is not supplied to the auxiliary booster 12,
The auxiliary booster 12 is idled. That is, the auxiliary booster 12 is separated from the main booster 11 and is independent of the main booster 11, and is in a lost motion state, that is, a so-called free state.

Therefore, the steering during normal driving is performed only by the main booster 11, and the auxiliary booster 12 operates by the main booster 11.
The steering of the main booster 11 is freely followed without substantially resisting the steering by the 11.

In the power steering 10 described above, the load boosting valve 20 is used for the main booster.
By making it possible to interlock the auxiliary booster 12 with the 11, the load-sensing characteristic was provided, and the operational feeling and steering stability were kept constant regardless of the empty vehicle and the loaded vehicle. When the used control valve 19 is configured as a speed-sensitive type, in addition to its load-sensitive characteristic, the optimum steering force corresponding to the vehicle speed can be obtained.
It has excellent speed response characteristics and improves the operational feeling and steering stability.

FIG. 4 shows another embodiment 110 of the power steering used in the vehicle of the present invention applied to the front uniaxial heavy truck 120.

This power steering 110 is a dual cylinder type, that is, a power cylinder is divided into two parts into a main booster 111 and an auxiliary booster 112, and its control valve 19 is incorporated in the main booster 111, and The load sensing valve 20 is arranged between the main booster 111 and the auxiliary booster 112, and the auxiliary hydraulic pipes 16, 1 in the power steering 10 described above are arranged.
7,18 cylinders of its main and auxiliary boosters 111,112
It is built into the body.

The power steering 110 is a sector gear shared by the main booster 111 and the auxiliary booster 112.
Pitman arm 115 fixed to center shaft 114 of 113 is connected to drag link 115, and front wheel shaft 121
The front wheels 122 of the vehicle can be steered.

As will be apparent from the characterized embodiments of the present invention described above with reference to the drawings, those of ordinary skill in the art to which the present invention pertains,
The subject matter of this invention is readily embodied in alternative forms which are derived from the nature and substance of the invention and which are objectively admitted to incorporate them. Of course, the contents of the present invention are commensurate with the subject of the invention and are essential to the establishment of the invention.

Benefits of the Invention As will be understood from the above, the power steering used in the vehicle of the present invention includes a main booster for steering a pair of wheel shafts swingably connected to both ends of an axle, and the main booster. Auxiliary booster that supplements the steering force of the vehicle, a hydraulic pump whose pump discharge rate is set to a value where the steering speed is less than 5 to 10 radians / second, and a main hydraulic pipe that connects the main booster to the hydraulic pump. , An auxiliary hydraulic pipe connecting the auxiliary booster to the main booster, a control valve arranged on the main hydraulic pipe for directional control of pressure oil supplied from the hydraulic pump to the main booster, and a valve inside the A valve body having a pair of load sensing chambers opened at both ends of the bore and the valve bore, and reciprocally slidably disposed in the valve bore. A spool that divides the load sensing chamber from the lube bore, and a pair of set pressure springs that are arranged in the load sensing chamber and press the opposite ends of the spool correspondingly. The main booster hydraulic pressure to the load sensing chamber for switching operation, and the main booster supplies pressure oil to the auxiliary booster to synchronously move the auxiliary booster to the main booster. Load sensing that cuts the pressure oil from the main booster to the auxiliary booster and short-circuits the auxiliary booster while short-circuiting the cylinder chambers of the auxiliary booster.
The power used in the vehicle of the invention as it includes a valve and a gear ratio set between 5 and 10 and a steering gear box which allows the movement of the steering wheel to be transmitted to its control valve.・
In steering, the steering wheel operating angle is reduced, which facilitates driving operation, and the steering wheel steering angle required by the auxiliary booster is reduced as the steering wheel operating angle is reduced. In the same way, the steering wheel becomes heavier due to stationary suspension when the vehicle is stopped, shifting or turning at a very low speed of the vehicle, and slow speed running or load of the vehicle. The steering force required therewith is supplemented by the auxiliary booster, that is, when the oil pressure of the main booster is lower than a predetermined pressure value, the load sensing valve is closed and the pressure oil is applied only to the main booster. And only its main booster is moved, while its auxiliary booster is
When the cylinder chambers are short-circuited to each other by the valve, separated from the main booster, independent, and moved very lightly, and when the hydraulic pressure of the main booster exceeds a predetermined pressure value, the load sensing The valve is opened, the hydraulic pressure is also supplied to the auxiliary booster, the auxiliary booster is driven in conjunction with the main booster, the steering force of the main booster is supplemented by the auxiliary booster, and thus the steering force is increased. Depending on the load, it can be changed appropriately, such as stationary siding, width-shifting and re-cutting, etc. are performed very lightly, and steering is also lightened even at low speed running.
In normal driving, steering is heavy, especially when the vehicle is running at high speed,
It suppresses wheel sensitivity, improves steering feel and steering stability, reduces steering fatigue, and avoids larger hydraulic pumps and larger piston pressure areas in power cylinders. Therefore, wasteful consumption of engine generated power is suppressed, and the fuel consumption rate of the engine is improved. Especially, in normal driving, as the auxiliary booster is separated from the main booster and is idled very lightly, The load is reduced, the wasteful consumption of power generated by the engine is suppressed, the fuel consumption rate of the engine is improved, and further, in the case where the vehicle is configured as a front two-axis or a front single-axis type. It is easily applicable and, as a result, is very useful and practical for large vehicles.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a specific example of a power steering applied to a front two-axle truck and used in a vehicle of the present invention in which a load sensing valve is closed,
FIG. 2 is a schematic diagram of the power steering shown in FIG. 1 with its load sensing valve opened, and FIG. 3 is a hydraulic circuit of the power steering shown in FIG. FIG. 4 is a schematic view partially showing a main booster and a control valve, and FIG. 4 is a schematic view showing another specific example of the power steering used in the vehicle of the present invention applied to a front single-shaft truck. Is. 11,111 …… Main booster, 12,112 …… Auxiliary booster, 13…
… Hydraulic pump, 14,15 …… Main hydraulic piping, 16,17,18 …… Auxiliary hydraulic piping, 19 …… Control valve, 20 …… Load sensing valve, 21 …… Oil reservoir, 24
...... Steering gear box.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-50070 (JP, A) JP-A-55-22561 (JP, A) Actually open 59-110270 (JP, U) Actual-open Sho-60- 157475 (JP, U) Actual development Sho-56-75065 (JP, U) Automotive Engineering Handbook Publication Committee Edition "Automotive Engineering Handbook" revised and revised 5th edition, October 30, 1965, published by Japan Society of Automotive Engineers , 12-11, left column, 1st line-same column, 18th line, Automotive Engineering Complete Book Editing Committee, "Automotive Engineering Complete Book, Volume 11, Steering, Suspension", August 20, 1980, Sankaidou, Issue 148 Line 2 from bottom-Page 149 Line 3

Claims (1)

[Claims] 1. A main booster for steering a pair of wheel shafts swingably connected to both ends of an axle, an auxiliary booster for compensating the steering force of the main booster, and a pump discharge amount of a steering speed of 5 or more. A hydraulic pump set to a value less than 10 rad / sec, a main hydraulic line connecting the main booster to the hydraulic pump, an auxiliary hydraulic line connecting the auxiliary booster to the main booster, and the main hydraulic line. A control valve, which is arranged in the pipe and controls the direction of pressure oil supplied from the hydraulic pump to the main booster, and a valve bore and a pair of load sensing chambers opened at both ends of the valve bore. Valves that have
A body, a spool that is reciprocally slidably arranged in the valve bore to partition the load sensing chamber from the valve bore, and a spool that is arranged in the load sensing chamber and corresponding to both end faces of the spool. It is composed of a pair of set pressure springs that are pushed and is arranged in its auxiliary hydraulic piping. It guides the oil pressure of its main booster to its load sensing chamber and is switched, and then supplies pressure oil from its main booster to its auxiliary booster. Then, the auxiliary booster is synchronously moved to the main booster, or the cylinder chamber of the auxiliary booster is short-circuited to each other and the pressure oil is cut off from the main booster to the auxiliary booster to make the auxiliary booster idle. Sensing valve, gear ratio set to 5-10, and steering wheel Power steering is used the movement of Lumpur vehicle including a steering gear box that can be transmitted to the control valve.