JPH0254270B2 - - Google Patents

Description

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

In general, power steering allows the driver to feel the weight of steering, that is, the steering resistance from the road surface.
They have been designed to generate a reaction force.

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

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

In addition, in power steering, the control valve that controls the direction of pressure oil supplied to and discharged from the power cylinder has multiple lands on the spool underwrapping to the pressure port, discharge port, and multiple cylinder ports. It is normal to

When the pressure port begins to open, the gap between the edge of the land and the edge of the port is widened on one side of the land corresponding to the pressure port, and at the same time, on the other side of the land, the gap between the edge of the land and the edge of the port is widened. , the gap between the edge of the land and the edge of the port is narrowed, so the pressure oil flowing through the narrowed gap becomes a jet, and the spool is pushed back by the pressure of the jet, so that this control・Vibration occurs in the valve, and as a result,
Noise was generated.

The purpose and problem of the present invention is to always obtain an appropriate reaction force according to the driving conditions of the vehicle and to facilitate steering.
In addition, the static and dynamic characteristics of the control valve are improved to avoid vibration of the control valve due to the movement of the valve spool, and to reduce steering fatigue. An object of the present invention is to provide a power steering system used in a vehicle that prevents noise generated by the vehicle.

In order to solve the above problems, the power steering system used in the vehicle of the present invention connects the power cylinder and the pressure port and the discharge port to a pair of power cylinder ports using a valve spool to connect the power cylinder and the discharge port of the oil pump. The power cylinder is supplied from the side, and at the same time the power
Directional control of the pressure oil returned from the cylinder to the suction side of the oil pump, and
a control valve having a reaction chamber formed within the spool and connected to the discharge side of the oil pump; and a control valve having a reaction chamber connected to the suction side of the oil pump. a reaction force regulating valve is disposed in the reaction communication passage, and a restriction is disposed in the communication hole formed in the valve spool communicating the pressure port with the reaction chamber. Damper or shock on the chamber
It is equipped with a structure that provides an absorber function, and when steering, the reaction force adjustment valve changes the pressure in the reaction chamber according to the driving conditions of the vehicle to obtain an appropriate steering force. For steering, the pressure port begins to open in the land of the valve spool, and on one side of the land, the gap between the edge of the land and the edge of the pressure port is widened to correspond. Then, on the other side of the land, the gap between the edge of the land and the edge of the pressure port is narrowed, and when a jet flow of pressure oil is generated in the narrowed gap, the pressure of the pressure oil jet is reduced. It is guided through the diaphragm from the communicating hole to the reaction chamber and is relaxed in the reaction chamber.

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

1 and 2 schematically show an embodiment 10 of a power steering system for use in a vehicle according to the invention, which is of the linkage type and applied to a cab-over type truck.

The linkage type power steering 10
an oil pump 11 as a hydraulic pressure supply source;
A flow control valve 12, a control valve 13, a power cylinder 14 located adjacent to one side of the control valve 13, and a power cylinder 14 located adjacent to the other side of the control valve 13. Shifter (not shown)
, a head portion (not shown) disposed adjacent to the shifter, and an end portion (not shown) disposed on the operating rod 50 side of the power cylinder 14, and the control valve 13
The reciprocating sliding of the valve spool 15 in the valve spool 15 switches and connects the discharge side and the suction side of the oil pump 11 to the pair of cylinder chambers 47 and 48 of the power cylinder 14. The oil pump 11
Reaction chamber 1 connected to the discharge side of
6, furthermore, a reaction communication passage 17,
The reaction chamber 16 is replaced with that oil.
Connected to the suction side of the pump 11, the reaction force adjustment valve 18
is disposed in the reaction communication passage 17, and a restriction 62 is formed in the valve spool 15 to connect the pressure port 22 to the reaction communication passage 17.
The reaction chamber 16 is disposed in a communication hole 54 connected to the chamber 16, and is provided with a damper or shock absorber function.During steering, the reaction force adjustment valve 18 adjusts the pressure according to the running conditions of the truck. The pressure in the reaction chamber 16 is varied to obtain the proper steering force, and for that purpose the pressure port 22 in the control valve 13 is correspondingly formed in the valve spool 15. the land begins to open, and on one side of the land, the gap between the edge of the land and the edge of the pressure port 22 widens, while on the other side of the land, the gap between the edge of the land and the edge of the pressure port 22 widens. and its pressure port 22
When the gap with the edge of the cylinder is narrowed and a jet flow of pressure oil is generated in the narrowed gap, the pressure of the pressure oil jet is guided from the communication hole 54 to the reaction chamber 16 through the throttle 62 and the reaction chamber 16 is discharged.・Assembled in chamber 16 where it will be relaxed.

The oil pump 11 is driven by an internal combustion engine (not shown) mounted on its cab-over truck, and pumps up pressurized oil from an oil reservoir (not shown) to drive the internal combustion engine. It is constructed so that a discharge amount of pressure oil can be obtained that is approximately proportional to the number of rotations.

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

The flow control valve 12 is a pump connected to the discharge side of the oil pump 11.
Port 51, control valve 13 described later
The control connected to the pressure port 22 side of
Valve port 52 and its suction port connected to the suction side of oil pump 11.
It consists of a casing equipped with a port 53, an oil return control spool (not shown), etc. arranged so as to be able to slide back and forth within the casing, and adjusts the flow rate of pressure oil sent to the pump port 51 side. The oil pump 11 is configured to send a predetermined flow rate to the control valve port 52 side and return the surplus flow rate from the suction port 53 to the suction side of the oil pump 11, that is, to the oil reservoir side. ing.

The flow control valve 12 is a flow control valve used in existing power steering.
Since it is configured similarly to a control valve,
A detailed explanation of its configuration will be omitted.

The control valve 13 has a valve casing 2 with a spool chamber 21 inside.
0, a valve spool 15 disposed in the spool chamber 21 so as to be reciprocally slidable, and a pair of spool stoppers 28 disposed in contact with both end surfaces of the valve spool 15, respectively.
29, and a spool passing through the spool stops 28, 29 and threaded within the valve spool 15 so as to slide the valve spool 15 back and forth through the spool stops 28, 29.・Shaft 19 and its spool・
A sleeve 25 is fitted onto the shaft 19 and disposed between a pair of spool stops 28, 29 thereof, and the spool stops 28, 29 are arranged so as to form a reaction chamber 16 inside the valve spool 15. A pair of reaction plungers 26 and 27 are respectively disposed between the inner circumferential surface of the valve spool 15 and the outer circumferential surface of the sleeve 25 on the sides, and a pair of reaction plungers 26 and 27 are disposed within the reaction chamber 16. , 27, and a pair of plunger stops 30, respectively, arranged on both sides of the spool chamber 21 so as to contact the outer end surfaces of the reaction plungers 26, 27.
31.

The valve casing 20 has a spool chamber 21 therein, and the spool chamber 21 is connected to the control valve of the flow control valve 12 in a predetermined position.
A pressure port 22 is formed which connects the spool chamber 21 to the suction side of the oil pump 11, and a pair of discharges are formed at a predetermined distance on each side from the pressure port 22 and connect the spool chamber 21 to the suction side of the oil pump 11. Ports 23 and 24 are formed respectively.

Therefore, the pressure port 22 is connected to the hydraulic piping 55.
through its flow control valve 12
The control valve port 52 of the oil pump 11 is connected to the control valve port 52 of the oil pump 11, and its discharge ports 23 and 24 are connected to the suction side of the oil pump 11 via hydraulic piping 56, respectively.

Of course, the pressure port 22 and the discharge ports 23, 24 communicate with ring grooves 57, 58, 59, respectively, formed in the valve casing 20 facing the spool chamber 21.

In addition, this pressure port 22 and its discharge port 2
3 and 24, a pair of power cylinder ports 32 and 33 are formed, respectively, to be connected to a pair of cylinder chambers 47 and 48 of the power cylinder 14, which will be described later.

Valve spool 15 is reciprocatingly slidably disposed within its spool chamber 21 and has its pressure port 22 and discharge ports 23, 24 switchably connected to its power cylinder ports 32, 33 and its oil pump. 11 to its power cylinder 14 and, at the same time, from its power cylinder 14 to its oil pump 1.
It controls the direction of the pressure oil returned to the suction side of the power cylinder.It has a cylindrical shape, and has a spool on its outer circumferential surface at a predetermined position facing the power cylinder ports 32 and 33. Groove 34,
35 was formed, and along with this, lands corresponding to the pressure port 22 and discharge ports 23, 24 were formed on the outer peripheral surface thereof at intervals in the axial direction. Of course, these lands are machined to underlap the ring grooves 57, 58, 59 of the pressure port 22 and discharge ports 23, 24.

The inner peripheral surface at both ends of the valve spool 15 is cut into a ring shape so as to slightly increase the inner diameter, and the plunger stopper 3 described later is cut out.
0 and 31 are configured to be accommodated in the notches 60 and 61.

Further, the valve spool 15 is provided with a communication hole 54 located in the land corresponding to the pressure port 22 and bored, so that the pressure oil from the pressure port 22 is transferred to the reaction chamber 1.
It was processed to lead to 6.

Spool stops 28 and 29 are respectively disposed within the spool chamber 21 so as to contact opposite end faces of the valve spool 15.

The spool stops 28, 29 are arranged so that the plunger stops 30, 31, which will be described later, are accommodated in the notches 60, 61 of the valve spool 15.
They are each provided with relief holes 36 and 37 through which the tips thereof pass.

The spool shaft 19 has one end disposed within the valve spool 15 and the other end passing through the valve casing 20 and connected to a shifter (not shown) to be described later. The part corresponding to the spool 15 is stepped,
The outer diameter is narrower than the other end.

Accordingly, the spool shaft 19 passes through the spool stops 28, 29 to cause the valve spool 15 to slide back and forth through the spool stops 28, 29. It is passed inside. In other words, the spool stopper 28, 29
are fitted onto both ends of a portion of the spool shaft 19 formed with a narrow outer diameter.

The sleeve 25 holds the spool shaft 19 between its pair of spool stops 28 and 29.
is fitted into the part formed with a narrow outer diameter,
The mounting positions of the spool stoppers 28 and 29 are regulated.

A pair of reaction plungers 26, 27
is in contact with the inner surfaces of the spool stoppers 28 and 29, and the valve spool 1
5 and the outer circumferential surface of the sleeve 25, respectively.

In that way, reaction plunger 2
6, 27, the reaction chamber 1 is placed inside the valve spool 15.
6 is formed.

Reaction spring 38 connects its reaction plungers 26, 27 to its spool.
It is arranged within its reaction chamber 16 so as to press against stops 28,29.

The plunger stoppers 30 and 31 have relief holes 36 and 36 in the spool stoppers 28 and 29, respectively.
37 and are disposed on both sides of the spool chamber 21 so as to contact the outer end surfaces of the reaction plungers 26, 27, respectively.

That is, if the spool shaft 19 is slid, for example to the left in FIG. 1, the valve spool 15 and reaction plunger 27 are also slid to the left, but the other reaction plunger 26 is in contact with the tip of the plunger stopper 30, so
The reaction plunger 26 is maintained in place.

Therefore, when the spool shaft 19 is so slid, its reaction chamber 1
The pressure of the hydraulic oil in the spool shaft 19 and the restoring force of the reaction spring 38 act as a reaction force against the sliding of the spool shaft 19, that is, the steering.

The power cylinder 14 has its control
Disposed adjacent to one side of the valve 13, integrally formed with the valve casing 20 of the control valve 13, and connected to the power cylinder ports 32, 33 of the control valve 13. cylinder bore 46
a power cylinder casing comprising a power cylinder casing; A power piston 49 is disposed to be reciprocally slidable within the power cylinder casing, and an operating rod 50 has one end fixed to the power piston 49 and the other end protruding outward through the power cylinder casing. It is configured.

A shifter (not shown) is located adjacent to the other side of the control valve 13, and
The control valve 13 is connected to the spool shaft 19 and controls the movement of a steering wheel (not shown) in a cab-over type truck, a gear box (not shown), a pitman arm (not shown), etc. to its spool shaft 19 via.

A head section (not shown) is located adjacent to the shifter and is connected to the chassis frame (not shown) side of the cab-over truck via an idler arm (not shown). be done.

The end part (not shown) is the power cylinder 1
4, and is connected to the chassis frame side as a force application point when the power steering 10 is in operation.

The reaction communication passage 17 is connected to the reaction chamber 16 of the control valve 13 described above.
is connected to the suction side of the oil pump 11.

The reaction communication passage 17 transfers the oil in the reaction chamber 6 to the oil pump 1.
A communication port 39 formed in the valve casing 20 of the control valve 13 and a communication hole 41 formed in the valve spool 15 facing the communication port 39 so as to be able to return to the suction side of the control valve 13. Contains.

Of course, the communication port 39 and communication hole 41
are provided with ring grooves 40 and 42, respectively, so that they communicate with each other not only when the valve spool 15 is placed in the neutral position, but also when the valve spool 15 is slid. .

The reaction force adjustment valve 18 has its reaction communication passage 1
It is set at 7.

The reaction force regulating valve 18 is reciprocally slidable within the spool chamber and a valve casing comprising a spool chamber (not shown) and a pair of ports 43, 44 in communication with the spool chamber. The spool is disposed in the spool and changes the cross-sectional area of the passage within the spool chamber in accordance with the reciprocating movement of the spool.

Therefore, the flow rate of the pressure oil flowing between the ports 43 and 44 is adjusted according to the reciprocating movement of the spool.
Adjustment of the pressure in the reaction chamber 16 at 3 is made.

Of course, the reaction force adjustment valve 18 may have any form as long as it can adjust the flow rate of the pressure oil flowing between the pair of ports 43 and 44.

The spool of the reaction force regulating valve 18 is configured to slide back and forth in accordance with the traveling speed of the cab-over type truck, thereby changing the cross-sectional area of the passage within the spool chamber.

That is, the spool is reciprocated so that the cross-sectional area of the passage is widened when the cab-over type truck travels at low speeds, and narrowed when the cab-over type truck travels at high speeds.

The spool is therefore slid by an actuator, e.g. a servo motor, in which a speed sensor (not shown) is inserted into the electrical circuit of the servo motor, and an output signal from the speed sensor is coupled to the spool. The servo motor is configured to be driven accordingly.

Further, the aperture 62 is disposed in the communication hole 54 and provides the reaction chamber 16 with a damper or shock absorber function.

This throttle 62 is connected to the pressure port 22.
Pressure oil directed from the air to the reaction chamber 16 is throttled in the communication hole 54, and the valve spool 15 is slid into the spool chamber 21 and the pressure port 22 is opened in its corresponding land. Then, on one side of the land, the gap between the edge of the land and the edge of the pressure port 22 widens, and at the same time, on the other side of the land, the gap between the edge of the land and the edge of the pressure port 22 widens. When the gap with the edge narrows and a jet flow of pressure oil is generated in the narrowed gap, the pressure of the pressure oil jet is throttled in the communication hole 54 and guided from the communication hole 54 to the reaction chamber 16. Reaction Chamber 1
6 to prevent vibration of the control valve 13 due to movement of the valve spool 15.

Of course, the inner diameter of the throttle 62 will vary depending on the inner diameter of the pressure port 22, the inner diameter of the communication hole 54, and the volume of the reaction chamber 16, but the inner diameter of the throttle 62 will vary depending on the inner diameter of the pressure port 22, the inner diameter of the communication hole 54, and the volume of the reaction chamber 16. - In the steering, it is desirable that the inner diameter of the aperture 62 be approximately 1 to 0.8 mm.

Furthermore, the aperture 62 shown in FIGS.
is shown as an orifice, but it can have any form as long as it throttles the pressure oil flowing through the communicating hole 54 with a predetermined throttling effect, and the communicating hole 54 can have the effect as the throttle 62. The inner diameter of the communication hole 54 is set to about 1 to
It is also possible to make it 0.8 mm.

Next, to describe the driving of a cab-over type truck to which the above-mentioned power steering 10 is applied, first, the internal combustion engine is operated, and the oil
When the pump 11 is driven, the flow rate of the pressure oil supplied from the oil pump 11 is adjusted by the flow control valve 12, and a predetermined flow rate is sent to the pressure port 22 of the control valve 13. It will be done.

The pressure oil sent to the pressure port 22 is returned to the suction side of the oil pump 11 through the discharge ports 23 and 24 when the valve spool 15 is in the neutral position; When the cylinder is slid in either direction by steering, the pressure oil flows into either one of the cylinder chambers 47, 48 of the power cylinder 14 and into the reaction chamber 16, depending on the sliding direction. The reaction force to such steering is provided by the pressure within the reaction chamber 16 and the reaction spring 38.

In such an operation of the power steering 10, when the cab-over type truck travels at low speed, the servo motor is driven by the output signal from the speed sensor, and the reaction force regulating valve 18 is driven by the output signal from the speed sensor.
The spool is slid to provide a relatively wide passage cross-sectional area within the spool chamber.

Therefore, the oil in the reaction chamber 16 is relatively smoothly returned to the suction side of the oil pump 11, so that the control valve 1
3, there is no large resistance to the sliding of the reaction plunger 26 or 27, and steering during low-speed running can be performed with a small operating force.

Of course, when the cab-over type truck is steered while stopped, the traveling speed is zero and the passage cross-sectional area of the reaction force adjustment valve 18 is maximized, so that the pressure inside the reaction chamber 16 is becomes close to atmospheric pressure, and the
Turning and turning can be done with extremely small operating force.

Furthermore, when the cab-over type truck travels at high speed, the servo motor is driven by the output signal from the speed sensor, and the reaction force regulating valve 1 is driven by the output signal from the speed sensor.
8 spools are slid to narrow the passage cross-sectional area within the spool chamber.

Therefore, the oil in the reaction chamber 16 is less likely to be returned to the suction side of the oil pump 11, creating a large resistance to the sliding of the reaction plunger 26 or 27 in the control valve 13, in other words. If so, a relatively large operating force is required for steering when driving at high speeds, improving driving stability.

In addition, in the case of steering as described above,
When the pressure port 22 is started to open at its associated land and the gap between the edge of the land and the edge of the pressure port 22 is narrowed and a jet flow of pressure oil occurs in the narrowed gap. , the pressure of the pressure oil jet passes through the communication hole 54 while being resisted by the restriction 62 to cause the reaction.
Since the control valve is guided and damped by the chamber 16, vibrations of the control valve due to movement of the valve spool 15 are avoided, and the noise generated due to the vibrations is prevented.

In the above-mentioned specific example 10, the reaction force adjustment valve 18
was explained as adjusting the amount of throttle according to the traveling speed of the cab-over type truck, but the configuration is also designed so that the amount of throttle is adjusted according to the rotational speed of the internal combustion engine mounted on the cab-over type truck. It is also possible to do so.

That is, in such a case, the reaction force regulating valve 1
An engine rotation speed detection sensor (not shown) is inserted into the electric circuit of the servo motor that slides the spool of No. 8, and the servo motor is driven according to the output signal from the sensor. be done.

As can be understood from the above, the power steering used in the vehicle of the present invention connects a power cylinder and a pressure port and a discharge port to a pair of power cylinder ports by switching between the power cylinder and the valve spool. directional control of the pressure oil supplied from the discharge side of the pump to its power cylinder and at the same time from the power cylinder back to the suction side of the oil pump; a control valve with a reaction chamber connected to the discharge side of the oil pump, and the reaction communication passage is connected to the reaction chamber.
a chamber is connected to the suction side of the oil pump, a reaction force regulating valve is disposed in the reaction communication passage, and a restriction is formed in the valve spool to connect the pressure port to the reaction chamber. In the power steering used in the vehicle of this invention, the pressure in the reaction chamber is adjusted depending on the vehicle running conditions by the reaction force adjustment valve. can be changed to obtain an appropriate reaction force, making steering easier and more reliable, and reducing steering fatigue.In addition, the aperture placed in the communication hole allows the reaction chamber to act as a damper or shock. Provided with an absorber function, the pressure port is started to open at its corresponding valve spool land, and the gap between the edge of the land and the edge of the pressure port is narrowed, and the pressure is increased in the narrowed gap. When a jet flow of oil is generated, the pressure of the pressure oil jet is guided through the communication hole to the reaction chamber while being resisted by the restriction, and is relieved, and the control valve as the valve spool moves. vibrations are avoided and the noise generated due to these vibrations is prevented, in particular the valve
The movement of the spool is stabilized and its control
The static and dynamic characteristics of the valve are improved, making it extremely practical.

As mentioned above, from the specific examples of the present invention explained with reference to the drawings, those who have ordinary knowledge in the technical field to which this invention pertains will understand the following:
Various design modifications and changes can be easily made, and furthermore, the content of this invention is essential to the realization of the invention that accomplishes the task of the invention,
It is derived from the technical essence of the invention, which is the nature of the invention, and can be easily replaced by an embodiment that is objectively recognized as incorporating it.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a specific example of the power steering used in the vehicle of the present invention, which is applied to a cab-over type truck as a linkage type, and FIG. FIG. 3 is an enlarged schematic diagram showing a throttle in power steering. 10... Power steering used in a vehicle, 11... Oil pump, 13... Control valve, 14... Power cylinder, 15
...Valve spool, 16...Reaction
Chamber, 17...Reaction communication passage, 18...
...Reaction force adjustment valve, 22...Pressure port, 47, 48
...Cylinder chamber, 54...Communication hole, 62...Aperture.

Claims (1)

[Claims] 1. A power cylinder, and a pressure port and a discharge port are switched and connected to a pair of power cylinder ports by a valve spool, and oil is supplied from the discharge side of an oil pump to the power cylinder,
At the same time, the oil from the power cylinder
Controls the direction of the pressure oil returned to the suction side of the pump,
The control valve includes a reaction chamber formed in the valve spool and connected to the discharge side of the oil pump, and in a steering device, the reaction communication passage is connected to the reaction chamber. the chamber is connected to the suction side of the oil pump, a reaction force regulating valve is disposed in the reaction communication passage, and a restriction is formed in the valve spool to connect the pressure port to the reaction chamber. Power steering used in vehicles is characterized by the fact that it is placed in a communication hole that allows the power steering to flow.