JPH0159943B2 - - Google Patents

Description

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

Generally, this type of power steering includes:
A flow control valve that controls the flow rate of pressurized oil according to the rotational speed of the internal combustion engine in order to make the steering wheel heavier and more stable when driving at high speeds than when driving at low speeds, so-called engine speed-sensitive flow rate. Regulating valves have been widely used.

Such an engine speed sensitive flow regulating valve has an oil return control spool movably disposed within the valve casing, and the oil return control spool is
Furthermore, it is equipped with a pin that passes through an orifice formed near the control valve port that is connected to the control valve spool side of the power steering device consisting of a control valve and a power cylinder, and the oil return・Most of them are designed so that the gap between the orifice and the pin can be adjusted according to the reciprocating movement of the control spool.

Therefore, when the flow rate of pressure oil supplied from the oil pump is low, the oil return
The control spool hardly slides,
Since the orifice is not extremely restricted by the pin, a flow rate of pressure oil corresponding to the rotational speed of the oil pump, that is, the engine rotational speed, is supplied to the control valve of the power steering device.
The steering is placed in a state where the steering can be rotated with a small operating force by being sent to the spool side, and when the flow rate of pressure oil supplied from the oil pump is large, that is, when the internal combustion engine is rotating at high speed. Sometimes the oil return control spool is slid, which causes some of the pressure oil to return to the suction side of the oil pump, and the orifice is throttled by the pin. From there, the reduced flow pressure oil is sent to the control valve spool side of the power steering system.

However, in this way, the control valve of the power steering system is
The method of reducing the flow rate of pressure oil sent to the spool side can change the weight of the handle when combined with a spring reaction type power steering device, and can be used in combination with a hydraulic reaction type power steering device. In combination, it is not possible to change the weight of the handle. The reason for this is that when a car changes course, the load acting on the steering wheel is the same regardless of the presence or absence of an engine speed-sensitive flow control valve, and the steering wheel acts against this load. This is because the power steering output required to turn the vehicle is equal to the product of the pressure-receiving area of the power piston and the hydraulic pressure acting on it. In other words, in the case of a hydraulic reaction type, the hydraulic pressure is led to the reaction chamber, and the hydraulic pressure and the reaction chamber are
The weight of the handle is the product of the pressure receiving area of the control valve spool in the chamber.
Therefore, the weight of the handle is not affected by the flow rate. In addition, in the case of the spring reaction type, the control valve spool is slid with the stroke necessary to generate the hydraulic pressure acting on the power piston, and the distance of that stroke and the spring constant of the reaction spring are The product is the weight of the handle. Therefore, the weight of the handle is affected by the flow rate since its stroke requirement varies with the flow rate.

The purpose and problem of this invention is to improve steering stability by making the steering wheel heavier when driving at high speeds than when driving at low speeds, and to improve responsiveness by preventing self-excited vibration of the control valve. Along with this, the response of the device has been improved, making it possible to implement both a spring reaction type and a hydraulic reaction type, and improving the power system used in vehicles, which are responsive to engine speed. It is in the provision of 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, a flow control valve, a control valve, and a power cylinder, the flow control valve being disposed in the valve chamber between the pump port and the control valve port. On the throttle side of the valve, a reaction valve is opened in the valve chamber and formed in the valve casing.
A control valve is provided with a control port, and the control valve is fitted into a pair of reaction chamber bores that are open at both ends and formed in the control valve spool, and the reaction chamber bores, respectively. ,
a pair of fixed reaction plungers disposed opposite each other in the spool chamber to form a pair of reaction chambers within the control valve spool; and a reciprocating sliding movement of the control valve spool. A pair of reaction communication passages formed in the control valve spool and a pair respectively arranged in the reaction communication passages so as to switch and connect the reaction chamber to the reaction port and the discharge port according to the control valve spool. At the reaction control port of the flow control valve, a pressure signal corresponding to the rotational speed of the internal combustion engine that drives the oil pump is obtained.・The pressure signal is guided to the reaction chamber through the port and the reaction communication passage, and the weight of the steering wheel at high speed is made more important than that at low speed by the pressure signal, and the control valve The weight of the spool is reduced by the reaction chamber bore, improving the response of the control valve, and at the same time, the self-excited vibration of the control valve spool due to the pressure signal is suppressed by the restriction of the reaction communication passage. There it is.

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

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

The power steering 10 includes an oil pump 11 driven by an internal combustion engine (not shown) mounted on the truck, a flow control valve 12, and a control valve 34.
and a power cylinder 37.

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

The flow control valve, that is, the engine speed sensitive flow rate adjustment valve 12, may be provided independently in the hydraulic piping downstream of the oil pump 11, or may be installed in the oil pump 11 or its control valve. It is integrated into the valve 34 and the power cylinder 37, and is connected to a pump port connected to the discharge side of the oil pump 11, and to supply ports 38 and 39 of the control valve 34, which will be described later. A control valve port 17, a suction port 15 connected to the suction side of the oil pump 11, a valve chamber 16 communicating between the pump port 14 and the suction port 15, and a valve chamber 1.
Its control valve port 1 at 6
A reaction control port 29 formed at a position near 7, fixed orifices 30 and 31 as a restriction formed in a partition wall 18 that partitions the control valve port 17 and the valve chamber 16, and a control thereof.・
a metering orifice 32 formed in the ventilate at the valve port 17;
The valve casing 13 is provided with a pilot communication passage 33 communicating between the metering orifice 32 and the outer portion of the valve chamber 16, and the pump port 14 and the suction port 15 are controlled to communicate with each other. and an oil return control spool 19 disposed within the valve chamber 16 so as to be slidable back and forth.

That is, the valve casing 13 corresponds to the lower part of the casing of the oil pump 11, and the valve casing 13 is connected to the discharge side of the oil pump 11 and has a substantially vertically extending upper part. the pump port 14 extended toward the pump port 14;
a control valve port 17 extending outwardly in a substantially vertical direction from the lower portion and connected to the suction side of the oil pump 11 and extending upwardly in a substantially vertical direction alongside the pump port 14; suction ports 15 are respectively formed.

The valve casing 13 also has a pump port 14 connected to its suction port 1.
5, valve chamber 16
is formed horizontally.

A partition wall 18 is integrally formed between such a valve chamber 16 and its control valve port 17, and a fixed orifice 30, 31 as a throttle is formed in the partition wall 18, respectively. .

Furthermore, its control valve port 1
A vent turret 7 is formed, and a metering orifice 32 is formed in the throat portion of the vent turret.

The metering orifice 32 is connected to the valve chamber 1 via a pilot communication passage 33.
It is connected to the outer part of 6.

Further, the reaction control port 29 is opened into the valve chamber 16 on the fixed orifice 30, 31 side so that the oil return control spool 19 is always open. It was formed on 13th. That is, this reaction control port 29 is located near the fixed orifices 30 and 31 and is located below the pump port 14.
An opening is formed in the valve casing 13 in the valve chamber 16 .

Valve casing 1 configured as described above
An oil return control spool 19 is disposed within the valve chamber 16 of No. 3 so as to be able to slide back and forth.

Its oil return control spool 19 has a relief valve chamber 2 inside.
1, and has a relief valve chamber 21 at its rear end and upper outer peripheral surface.
A spool main body 20 is formed with a pressure oil inlet 22 and a pressure oil outlet 23 and has a stopper 26 fixed to its tip, and its relief.
Inside the valve chamber 21, there is a ball poppet 24 for opening and closing the pressure oil inlet 22, and a ball poppet 24 for opening and closing the pressure oil inlet 22.
A return spring 25 is disposed within the relief valve chamber 21 to urge the poppet 24 against the pressure oil inlet 22.

If the oil return control spool 19 so configured is placed within the valve chamber 16 of the valve casing 13, it will cooperate with the oil return control spool 19 to control the valve.・Chayamba 1
A back pressure chamber 28 is formed in a portion closer to the outside of 6.

Of course, the back pressure chamber 28 is connected to the metering orifice 32 via the pilot communication passage 33 mentioned above.

Further, a return spring 27 is arranged in the back pressure chamber 28 to press the oil return control spool 19 inward.

Therefore, the oil return control spool 19 is normally pressed inward by the return spring 27, and the stopper 26 at the tip of the spool body 20 is pressed against the partition wall 18.
placed in contact with.

Of course, in such a situation, pump port 1
Contact between 4 and Saxion Port 15 has been severed.

The control valve 34 is of a hydraulic reaction type and is manufactured integrally with the power cylinder 37. That is, the control valve 3
The casing 35 of No. 4 is a control valve.
The power cylinder casing 43 of the power cylinder 37 includes a spool chamber 36 for the spool 49 and a cylinder bore for the power piston 62 . teeth,
The casing 35 of the control valve 34
is integrally formed.

A pair of supply ports 38 and 39 are formed on both sides of the casing 35 to communicate with both ends of the spool chamber 36, respectively. Of course, the supply ports 38, 39
are respectively connected to the control valve port 17 of the flow rate regulating valve 12 described above via the oil supply pipe 67.

Further, a reaction port 40 is formed at approximately the center of the casing 35 so as to communicate with approximately the center of the spool chamber 36 in the axial direction. Of course, the reaction port 40 is connected to the reaction control port 29 of the flow rate regulating valve 12 via the reaction piping 69.

Further, in the casing 35, the supply ports 38, 39 and the reaction port 40
A pair of discharge ports 41 and 42 are formed between the spool chamber 36 and the spool chamber 36, respectively. Of course, the discharge ports 41 and 42 are connected to the drain oil pipe 68.
It is connected to the suction side of the oil pump 11 mentioned above through.

In such a casing 35, between the supply ports 38, 39 and the discharge ports 41, 42 there is a pair of power cylinder ports 60, 61 in communication with the spool chamber 36. each formed.

A pair of columnar reaction plungers 47 and 48 are protruded from the inner surfaces of both end walls that close both ends of the spool chamber 36 and are fixed to the end walls, respectively.

In the spool chamber 36 of the casing 35 configured in this way, the control valve spool 49, which slides in response to a steering operation, is connected to the reaction plunger 4.
7, 48 so as to be able to slide back and forth.

The control valve spool 49 is
Reaction chamber bores are formed from both end faces toward the center with an inner diameter into which the reaction plungers 47, 48 are fitted, and a depth greater than the length of the reaction plungers 47, 48. There is.

The control valve spool 49 thus manufactured is fitted with its corresponding reaction plungers 47 and 48 in both reaction chamber bores, and its reaction chamber bores are fitted with corresponding reaction plungers 47 and 48.
It is reciprocally slidably disposed within its spool chamber 36 while being guided by plungers 47,48.

Therefore, in such a state, a pair of reaction chambers 5 are disposed within both end portions of the control valve spool 49 in cooperation with the reaction plungers 47 and 48.
0,51 is formed.

Of course, that control valve spool 4
9 is a plurality of spool grooves 52, 53, 5 formed at appropriate intervals in the axial direction on the outer periphery.
4 and 55, respectively.

The inner spool grooves 54, 55 are connected to the reaction chambers 51, 5 located on opposite sides of each other.
0 through a pair of reaction communication passages 56 and 57, respectively.

Furthermore, the pair of reaction communication passages 56,
57 includes apertures 58 and 59, respectively.
That is, when pressure oil is supplied from the reaction port 40 to the reaction chamber 51 or 50 via the reaction communication passage 56 or 57, the control valve spool 49 is prevented from automatically vibrating. The reaction communication passages 56 and 57 have a throttle 5.
8 and 59 are formed, respectively.

Furthermore, a pin 66 for sliding the control valve spool 49 back and forth is attached to the substantially central position of the control valve spool 49 described above.

Of course, one end of the pin 66 is connected to the casing 35 so that it is driven in response to steering operation.
It passes through and is connected to the steering shaft (not shown) side.

Therefore, the control valve spool 49 is reciprocated by the steering operation, and in response to such reciprocating sliding, the supply port 3 is
8 and 39 are selectively connected to the exhaust ports 41 and 42 or the power cylinder ports 60 and 61.

Further, a power piston 62 is disposed in the cylinder bore of the power cylinder casing 43 of the power cylinder 37 so as to be able to reciprocate and slide, and the power piston 62 allows the cylinder bore to connect to the pair of cylinders. It is partitioned into chambers 44 and 45.

The cylinder chambers 44 and 45 are connected to communication passages 70 and 7.
1, the above-mentioned control valve 34
are connected to power cylinder ports 60 and 61, respectively.

Of course, it is fixed to the power piston 62,
The tip of the push rod 63 protruding outward from the power cylinder casing 43 is attached to the chassis frame 64 side of the cab-over type truck.
On the opposite side of 3, the tip of a rod 65 fixed to its casing 35 is attached to the side of a drag link (not shown) that drives a steering arm (not shown).

Next, the operation of the power steering 10 described above will be explained.

First, when the internal combustion engine of the cab-over type truck is operated and the oil pump 11 is driven,
Pressure oil according to the rotation of the oil pump 11,
It is sent to the pump port 14 of the flow control valve 12.

When the flow rate of pressure oil supplied from the oil pump 11 is low, that is, when the internal combustion engine is operated at low speed, the flow rate regulating valve 12
oil return control spool 1
9 is positioned on the inside (left side in the figure) by the return spring 27, and even if it moves slightly outward (to the right side in the figure) depending on the flow rate of the pressure oil, the pump port 14 and suction・
Since communication with the port 15 is broken, the pressure oil flows through the fixed orifices 30, 31 of the partition wall 18.
from the control valve port 17 to the supply ports 38, 3 of the control valve 34 forming part of the power steering system.
9 and a portion of the pressure oil is sent from the reaction control port 29 to the reaction port 40 of the control valve 34.
sent to.

In such conditions, when control valve spool 49 of control valve 34 is in the neutral position, its supply ports 38, 39 and reaction port 4
0 is returned to the suction side of the oil pump 11 through the discharge ports 41 and 42, but if the control valve spool 49 is slid to either the left or right by steering operation. , the pressure oil sent to the supply port 38 or 39 is supplied to the cylinder chamber 44 of the power cylinder 37,
The pressure oil sent to either the left or right side of the chamber 45 and the reaction port 40 is sent to the reaction chamber 50 or 51.

For example, if the control valve spool 49 is slid to the right in the figure, the outer spool groove 53 will be connected to the supply port 39 side and the inner spool groove 54 will be connected to the reaction port 40. You will be contacted. That is, the pressure oil sent to the supply port 39 is sent to one cylinder chamber 45 of the power cylinder 37 via the spool groove 53 on the outside and the communication path 71, and is also sent to the reaction port 40. The pressure oil sent to the reaction chamber 51 is sent to the reaction chamber 51 via the spool groove 54 and the reaction communication passage 56 inside the spool groove 54 .

Therefore, the reaction force of the steering in such a state is given by the pressure oil sent to the reaction chamber 51, and the pressure oil sent to the reaction chamber 51, in other words, the flow rate adjustment valve. The pressure of the pressure oil sent from the 12 reaction control ports 29 is transferred from the control valve port 17 to the cylinder chambers 44, 4.
Since the pressure oil sent to the oil pump 5 increases approximately in proportion to the rotation speed of the oil pump 11,
When driving at low speeds, the reaction chamber 5
The pressure of the pressure oil in the control valve spool 49 is relatively low (the difference with the oil pressure in the power cylinder is small), so it does not create a large resistance to the sliding of the control valve spool 49, and the control valve spool 49 is steered with a small operating force. be placed in a position to obtain.

In this case, the control valve spool 49, lightened by the reaction chamber bore, is quickly slid and as the pressure oil begins to flow into the reaction chamber 51, the flow of pressure oil is , self-excited vibration is suppressed under the influence of the aperture 58.

Of course, that control valve spool 4
When 9 is slid to the left in the figure, an operation opposite to the above-mentioned operation is performed, so a description of such operation will be omitted.

Also, when the flow rate of pressure oil supplied from the oil pump 11 is large, that is, when the internal combustion engine is operated at high speed, the oil return control spool 19 of the flow rate regulating valve 12
moves outward (to the right in the figure) against the return spring 27, and the pump port 14 and suction port 15 are brought into communication.

That is, the pressure oil sent to the pump port 14 is returned to the suction side of the oil pump 11 from the suction port 15, passes through the fixed orifices 30, 31 of the partition wall 18, and is then transferred to the control valve port. 17 to the supply ports 38, 39 of the control valve 34, and a portion of the pressure oil is sent from the reaction control port 29 to the control valve 34.
is sent to reaction port 40 of valve 34.

Of course, as in the case described above, if the control valve spool 49 of the control valve 34 is slid to either the left or the right, the flow is sent to the supply port 38 or 39 depending on the direction of the slide. The pressure oil is sent to either the left or right cylinder chamber 44 or 45 of the power cylinder 37, and the pressure oil sent to the reaction port 40 is sent to the reaction chamber 50 or 51.

Therefore, when driving at high speed, the oil pump 11
Since the pressure of the pressure oil in the reaction chamber 50 or 51 becomes relatively high compared to the cylinder chamber pressure approximately in proportion to the rotation speed of the cylinder,
This creates resistance to the sliding of the control valve spool 49 and allows the steering to be performed with a relatively large operating force.In other words, the weight of the steering becomes heavier than when driving at low speeds, resulting in stable driving at high speeds. Improves sex.

In this case, high pressure oil is selectively directed into the reaction chambers 50 and 51, and when the oil begins to flow into the reaction chambers 50 or 51, the flow of the oil is as follows: Under the influence of the aperture 59 or 58, self-excited vibration is suppressed.

The power used in the vehicle of this invention described above
In the steering 10, the power steering device consisting of the control valve 34 and the power cylinder 37 has been described as a hydraulic reaction type, but if a spring reaction type is used, the reaction control port 29 It is only necessary to use the system blindly, and in that case, it functions as a known engine rotation sensitive power steering system, and of course, substantially the same effect as described above can be obtained.

As understood from the above, the power steering used in the vehicle of the present invention includes an oil pump, a flow control valve, a control valve, and a power cylinder. On the throttle side of the valve, which is located in the valve chamber between the pump port and the control valve port, a reaction valve is formed in the valve casing and opens into the valve chamber.
A control valve is provided with a control port, and the control valve is fitted into a pair of reaction chamber bores that are open at both ends and formed in the control valve spool, and the reaction chamber bores, respectively. ,
a pair of fixed reaction plungers disposed opposite each other in the spool chamber to form a pair of reaction chambers within the control valve spool; and a reciprocating sliding movement of the control valve spool. A pair of reaction communication passages formed in the control valve spool and a pair respectively arranged in the reaction communication passages so as to switch and connect the reaction chamber to the reaction port and the discharge port according to the control valve spool. Therefore, in the power steering used in the vehicle of this invention, the flow rate of pressure oil to properly drive the power cylinder is controlled at the control valve port of the flow control valve. In addition, at the reaction control port of the flow control valve, a pressure signal corresponding to the rotational speed of the internal combustion engine that drives the oil pump is obtained, and that pressure signal is obtained at the reaction control port of the flow control valve. The weight of the steering wheel is guided to the reaction chamber through the port and reaction communication passage, and the weight of the steering wheel is determined according to the engine speed.In other words, when driving at low speed, the weight of the steering wheel is
Light weight, reduces fatigue caused by steering operation,
In addition, when driving at high speeds, the weight of the steering wheel becomes heavier than when driving at low speeds, improving steering stability, and the control valve spool is lighter due to its reaction chamber bore. The response of the control valve is improved, and at the same time, self-excited vibration of the control valve due to the pressure signal is prevented by the restriction of the reaction communication passage, improving the response of the device.
The device can be implemented as a spring reaction type or a hydraulic reaction type that is sensitive to engine speed, making it extremely practical and widely applicable to passenger cars, trucks, buses, etc.

[Brief explanation of drawings]

The figure is a schematic diagram showing a specific example of the power steering system used in the vehicle of the present invention applied to a cab-over type truck. 10... Power steering used in vehicles, 11... Oil pump, 12... Flow
Control valve, 13... Valve casing, 14... Pump port, 15... Suction port, 16... Valve chamber, 17
...Control valve port, 19 ...Oil return control spool, 29
...Reaction control port, 3
0, 31...Fixed orifice, 34...Control valve, 35...Casing, 36...Spool chamber, 37...Power cylinder,
38, 39... Supply port, 40... Reaction port, 41, 42... Discharge port, 43...
...Power cylinder casing, 47, 48...
...Reaction piston, 49... Control valve spool, 50, 51... Reaction chamber, 56, 57... Reaction communication passage, 62... Power piston, 63... Push rod.

Claims (1)

[Claims] 1. An oil pump, a valve chamber, a pump port and a suction port connecting the valve chamber to the oil pump, a control valve port connected to the valve chamber, and a valve casing consisting of a restriction arranged in the valve chamber between the pump port and the control valve port, the discharge amount of pressure oil discharged from the control valve port, and the an oil return control spool reciprocally slidably disposed within the valve chamber to adjust the return amount of pressure oil returned to the suction port; a flow control valve having a reaction control port formed in the valve casing and opening into the valve chamber on its throttle side so as to be open; a pair of supply ports connecting a control valve port of a control valve to each side of its spool chamber, at approximately the axial center of the spool chamber; a reaction port connecting to the reaction control port; a pair of exhaust ports connecting the spool chamber to the suction side of the oil pump, respectively, between the supply port and the reaction port; and the supply port. a control valve casing comprising a pair of power cylinder ports connected to the spool chamber between the control valve casing and the discharge port thereof, and switchingly connecting the supply port to the discharge port and the power cylinder port; a control valve spool reciprocally slidably disposed within the spool chamber; a pair of reaction chamber bores formed in the control valve spool and open at both ends; Depending on the reciprocating sliding of the control valve spool,
a pair of reaction communication passages formed in the control valve spool to selectively connect the reaction chamber bore to the reaction port and the discharge port;
A pair of apertures arranged in each of the reaction communication passages are fitted into the reaction chamber bore, respectively, and the control
a control valve integral with the control valve casing, comprising a pair of fixed reaction plungers disposed opposite each other in a spool chamber to form a pair of reaction chambers within the valve spool; a power cylinder casing having a cylinder bore shaped like a cylinder and connected to a pair of power cylinder ports of the control valve; The power piston is arranged to be able to reciprocate and slide within the cylinder bore so as to form a pair of cylinder chambers within the cylinder bore, and a push rod connected to the power piston. Power steering used in vehicles including power cylinders.