JP2675128B2 - Full hydraulic steering system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an all-hydraulic steering system.

2. Description of the Related Art A conventional hydraulic pump system is desired to develop a steering device that simultaneously performs steering operation and actuation of auxiliary devices. As a solution to this, for example, a steering device shown as A'in FIGS. Has already become known.

Referring to FIGS. 9 to 11, in this drawing, 70 is a steering cylinder, 71 is a tank, 72 is a hydraulic pump, 73 and 74 are relief valves, and 75 is auxiliary equipment,
The steering device A'is as disclosed in, for example, Japanese Patent Publication No. Sho 58-19506, and 1'is a valve housing,
7'is a metering portion formed by inner and outer tooth members, 16 'is a switching valve, 19' is an inlet port, 20 'is an auxiliary fluid port, 21 and 2
2 indicates a right exit port and a left exit port to the steering cylinder, and 76 indicates an exit port to the tank 71.

In the steering system as described above, at the neutral position N of the switching valve 16 'of the steering device A', the oil discharged from the hydraulic pump 72 is the inlet port 1 as shown in FIG.
9 ', auxiliary fluid port 20', and maximum displacement position R
In M or LM, as shown in FIG. 11, the cylinder 70 moves to the stroke end position and the oil return circuit is blocked, so the oil discharged from the hydraulic pump 72 is
Through the relief valve 73, almost the total discharge amount of the pump 72 is supplied to the auxiliary equipment 75 for its operation, but at the steering position R or L of the switching valve 16 ',
As shown in the figure, most of the oil used for steering returns from the outlet port 76 to the tank 71, and there is a problem that the flow rate used in the auxiliary equipment 75 becomes small.

In addition to this, the flow rate to the auxiliary devices fluctuates due to the change in the steering speed according to the relational expression of pump discharge flow rate-flow rate proportional to steering speed = flow rate flowing to auxiliary devices, which affects the operation of auxiliary devices. There was also the problem of doing.

These problems are serious in a vehicle in which simultaneous operation of steering and auxiliary equipment can frequently occur. Therefore, in an inexpensive system with one pump and no shunt valve, no matter what steering state, However, there has been a demand for the development of a steering device that can use almost all of the pump discharge amount for operating auxiliary equipment.

Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional steering device, and to use almost all of the discharge amount of the pump for activating auxiliary equipment at all times, and meet the conventional demand. It is to provide a steering device capable of performing the above.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides an auxiliary fluid port for supplying fluid to auxiliary equipment to a housing and the drive shaft of a spool in the conventional full hydraulic steering device. A drain port that communicates the arranged internal space with the outside is provided, and regardless of the position of the switching valve, the inlet port and the auxiliary fluid port communicate with each other with or without the outlet port. Is supplied to the auxiliary fluid port.

Action In the above-mentioned full hydraulic steering system, even if the switching valve is brought to the neutral position, the left / right displacement position and the left / right maximum displacement position in accordance with the steering operation, almost the entire discharge amount of oil of the pump is directly supplied from the inlet port, or After passing through the steering cylinder via the left and right outlet ports, it is circulated to the auxiliary fluid port. Collected and discharged to the outside through the drain port communicating with this.

In the embodiment shown in the drawings, A is a steering device, 1 is a valve housing, and a spacer plate 8, a measuring unit 7, and an end cap 9 are sequentially arranged on the right side in FIG. It is connected to the housing 1.

The housing 1 is provided with five ports, a radial inlet port 19, an auxiliary fluid port 20, a right outlet port 21, a left outlet port 22 and a drain port 23. The center hole 18 has first to fifth annular grooves 27, 2 communicating with these ports.
8,29,30,31 are formed.

A switching valve 16 is rotatably arranged in the center hole 18, and the switching valve 16 has a rotatable spool 2 and a sleeve 3 cooperating therewith, and an input shaft (not shown) is splined at one end of the spool 2. It is designed to be combined.

In FIG. 1, 5 is a centering spring having both ends fitted in through holes provided in the spool 2 and the sleeve 3 as shown in FIG. 2, and 4 is a tapered hole of the spool 2 at both ends as shown in FIG. After penetrating the inside of the sleeve 41 so as to be movable in the circumferential direction, a stopper pin 6 supported by a through hole of the sleeve 3, 6 is a drive shaft, and 11 is a bushing provided between the outer periphery of the left end of the spool 2 and the housing 1. Show.

The drive shaft 6 extends in the inner space 53 of the spool 2 in the axial direction, and a fork portion is provided at one end thereof through which the stopper pin 4 penetrates, and a splined head portion 17 is provided at the other end. There is.

The measuring portion 7 meshes with the internal tooth member 7-1 and the internal teeth of the internal tooth member 7-1, has one tooth less than that, and the internal tooth member 7-1.
External tooth member 7 that is eccentrically provided inside and that rotates and revolves
-2, and a spline is provided in the center hole 18 of the external tooth member 7-2, and the spline of the head portion 17 of the drive shaft 6 is engaged with this spline.

The sleeve 3 has first to fifth annular grooves 27, 28,
A plurality of through holes 32, 34, 35, 36, 3 communicating with 29, 30, 31 respectively
7, 38 are arranged at equal intervals in the circumferential direction, the through holes 36 are in the same phase position as the odd through holes 32, and the through holes 37 are in the same phase position as the even through holes 32. , Through hole 3
3, 34 and 35 are at intermediate positions of the through hole 32 and are arranged at the same phase position with each other.

As shown in FIG. 4, the spool 2 has a through hole 38 from the left side.
And an annular groove 40 communicating with the taper hole 41, an annular groove 39 located to the right of the taper hole 41, a first linear groove 42 extending axially from the annular groove 39, and in the same direction in the middle of these linear grooves 42. A second linear groove 43 extending, a narrow third linear groove 44 extending in the same direction from the tip of the linear groove 43, and a fourth linear groove 45 spaced apart from the tip of the linear groove 44 and extending in the same direction are provided. Has been.

The housing 1 is provided with a radial flow passage 46 communicating with the through hole 32 of the sleeve 3 and an axial flow passage 50 communicating therewith, and the spacer plate 8 communicates the flow passage 50 with the inside of the measuring unit 7. A flow path 59 is provided. Further, the housing 1 is provided with first, second and third extension passages 47, 48 and 49 in the radial direction which communicate with the first, second and fifth annular grooves 27, 28 and 31, respectively.
First and second check valves 24 and 25 are provided in the communication passage 51 of the extension paths 47 and 48 and the communication passage 52 of the first and third extension paths 47 and 49, respectively.

The first check valve 24 is not designed to have a specific structure, but the second check valve 25 is required to have a specific structure for the reason described below. Refer to FIG. explain.

54 is a press-fitting bush, 55 is a retainer, 56 is a ball valve, 57 is a seat surface, and 58 is a spring that biases the ball valve 56 in the opening direction.

FIGS. 6 to 8 show an example of a state in which the steering device as described above is arranged in the entire hydraulic system, and since many parts thereof are the same as those of the above-mentioned known system, such parts are the same. The description will be omitted by citing the reference numerals.

 The operation of the above will be described.

(1) Basic operation In FIGS. 1 to 3, when the spool 2 is rotated in either the left or right direction, the centering spring 5 bends and an angular displacement occurs between the spool 2 and the sleeve 3. Due to this angular displacement, as will be described later, the high-pressure oil flowing from the inlet port 19 flows into the pressure chamber formed by the inner and outer tooth members 7-1 and 2, and the high-pressure oil rotates the outer tooth member 7-2. This rotation is transmitted to the sleeve 3 via the drive shaft 6 and the stopper pin 4, and the action of canceling the initial angular displacement occurs.
Oil proportional to the amount of rotation of spool 2 left and right outlet ports 21,2
It is sent into the steering cylinder 70 from either of the two, and at this time, the measuring unit 7 exerts a flow rate measuring function.

Such a basic operation is not unique to the present invention, and is similarly performed in the conventional device.

(2) Operation when the valve is in neutral The relative positional relationship between the spool 2 and the sleeve 3 at this time is shown in FIGS. 4 (A) and 6 (N).

In this case, the oil that has flowed in from the inlet port 19 by the pump 72 enters the inside through the first annular groove 27 and the through holes 33, 34 of the sleeve 3, and the oil that enters the through hole 33 is the fourth oil of the spool 2.
Although it enters the straight groove 45 and stops there, the oil that has entered from the through hole 34 flows into the through hole 35 of the sleeve 3 through the third and second straight grooves 44 and 43, and then the second annular groove 28. Through the auxiliary fluid port 20 to the auxiliary equipment 75.

(3) Operation when the valve is displaced to the right The relative positional relationship between the spool 19 and the sleeve 20 at this time is shown in FIGS. 4 (B) and 7R.

This is the case when the spool 2 is rotated to the right, and in this case, the oil that has flowed in from the inlet port 19 flows through the following two systems.

First, the first system includes a first annular groove 27, a through hole 33, a through hole 33 and a fourth straight groove 45, a first orifice 60, a fourth straight groove 45, a fourth straight groove 45 and a through hole 33. And the second orifice 61, the through hole 32, the flow paths 46, 50, 59, the pressure chamber in the measuring unit 7, the flow paths 59, 50, 46, the through hole 32, the through hole 32 and the first linear groove 42. And a third orifice 62 formed by the first linear groove 42, a fourth orifice 63 formed by the first linear groove 42 and the through hole 36, a through hole 36, a third
It is a system that flows to the annular groove 29 and the right exit port 21. By the series of oil flow in this system, the oil measured via the metering section 7 flows from the right outlet port 21 to the cylinder 70,
The oil that has finished its work in the cylinder 70 in this way enters the left outlet port 22, and enters the fourth annular groove 30, the through hole 37, the through hole 37 and the second through hole 37.
Fifth orifice 64 formed by linear groove 43 and second linear groove
43, the second orifice 43 formed by the second linear groove 43 and the through hole 35, the through hole 35, and the second annular groove 28 to flow from the auxiliary fluid port 20 to the auxiliary equipment 75.

Next, in the second system, the first annular groove 27, the through hole 34, the sixth orifice 65 formed by the through hole 34 and the third linear groove 44, the third linear groove 44, the second linear groove 43, and the seventh linear groove 44. It is a system that flows to the orifice 66, the through hole 35, the second annular groove 28, and the right outlet port 21.

As can be seen from the above, the flows of the first and second systems eventually join at the right outlet port 21, and therefore the inlet port.
The oil that has entered from 19, that is, the oil of substantially the entire discharge amount of the pump 72 will flow to the auxiliary equipment 75 via the right outlet port 21.

(4) Operation at maximum right displacement of valve The relative positional relationship between the spool 2 and the sleeve 3 at this time is shown in FIGS. 4 (C) and 8 RM.

This is when the spool 2 is further rotated rightward so that the angular displacement between the spool 2 and the sleeve 3 becomes maximum, and the stopper pin 4 engages with one end wall of the tapered hole 41.

In this case, the sixth orifice opened in (B)
Others are in the same state as in (B) except that 65 is blocked, and therefore the flow of the second system in the operation when the valve is displaced to the right is stopped, and the other operations remain.

When the valve is displaced to the left, the directions are opposite and only the left outlet port 22 is used, so the description is omitted.

When the piston of the cylinder 70 reaches the end position due to the valve displacement in the above, since the relief valve 73 is provided between the inlet port 19 and the auxiliary fluid port 20, the total discharge amount of the pump 72 can be achieved without any inconvenience. Is auxiliary equipment 75
Found to be used in the operation of.

When high pressure acts on the auxiliary fluid port 20 in each of the above operations (2) (3) (4), the cylindrical gap between the spool 2 and the sleeve 3, the sleeve 3 and the housing 1, and the housing 1 and the spacer plate. 8. A leak of oil occurs from the plane gap between the spacer plate 8 and the internal tooth member 7-2, and this leak enters the internal space 53 of the spool. This internal space 53
Communicates with the drain port 23 through the taper hole 41 of the spool 2, the annular groove 40, the through hole 38 of the sleeve 3, and the fifth annular groove 31 of the housing 1. Therefore, the above-mentioned leak passes through this path to the tank. Returned to 71. Since the drain amount at this time is small, the drain port 23 may have a small diameter.

In this case, since the internal space 53 communicates with the drain port 23, the internal pressure is always kept at the same low pressure as the tank 71.

(5) Operation during emergency steering In this type of steering system, the steering function of the hand pump, that is, even when the pump 72 does not discharge oil, is used even in an emergency when the engine or pump has failed. It is necessary to operate the switching valve 16 by the handle operation to suck up the oil from the tank 71 and the auxiliary fluid port 20, and the first and second checks are provided to exert such a function. Valves 24 and 25.

In this case, a large torque manual input is required,
Inevitably, the valve will be in its maximum displaced position.

FIG. 8 shows that the cylinder 70 is a single rod type,
This is the case when the auxiliary fluid port 20 is blocked and is in the right steering RM position. In such a case, due to the difference in the pressure receiving area ratio of the cylinder 70, the input port
Auxiliary fluid port 20
If the auxiliary device 75 is blocked, the fluid to be passed through the auxiliary fluid port 20 enters the inlet port 19 via the first check valve 24, and the flow rate is sucked up by the inlet port 19 when the auxiliary device 75 is blocked. More than required flow rate. Therefore, if the second check valve 25 is of a normal check valve type, it will be blocked and the emergency steering cannot be operated.

However, since the second check valve 25 has the above-described structure and is always opened during an emergency, in such a case, the oil due to the difference in the cylinder pressure receiving area ratio is discharged from the inlet port 19 to the second position. Check valve 25,
After returning to the tank 71 through the drain port 23, normal emergency steering operation becomes possible.

EFFECTS OF THE INVENTION The present invention is as described above, and in the conventional all-hydraulic steering system, an auxiliary fluid port for supplying fluid to auxiliary equipment is provided in a housing, an internal space in which the drive shaft of the spool is arranged, and an external space. Is provided so that the inlet port and the auxiliary fluid port communicate with each other regardless of the position of the switching valve regardless of the position of the switching valve. Even if it is in a different operating position, almost the entire amount of oil discharged from the pump can be used for operating auxiliary equipment. Therefore, it is possible to use a small-capacity pump, which can be provided at low cost, as well as horsepower loss. It is possible to reduce the oil consumption and to improve the performance by making the amount of oil supplied to the auxiliary equipment almost constant without changing by changing the operating position of the switching valve, and improving the internal device It is possible to prevent the internal pressure from increasing due to the increase in the amount of oil by discharging the oil through the drain port, and to prevent the occurrence of a failure inside the device due to the increase in the internal pressure.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of an embodiment of the present invention, FIGS. 2 and 3 are vertical sectional side views of different parts of the same, and FIG. 4 shows different operating states of the switching valve of the same embodiment ( FIGS. 5 (A), 5 (B) and 5 (C) are partially enlarged plan views, FIG. 5 is an enlarged cross-sectional view of one check valve portion of the above, and FIG. 6 is a steering device when the switching valve of the same is in the neutral position. FIG. 7 is a schematic diagram of the steering device when the switching valve is in the right shift position, and FIG. 8 is a schematic diagram of the steering device when the switching valve is in the maximum displacement position. Fig. 9 is a schematic diagram when the switching valve of the conventional steering device is in the neutral position, and Fig. 10 is a schematic diagram when the switching valve of the same is in the right displacement position. FIG. 11 is a schematic diagram when the switching valve of the same is in the maximum displacement position. 1 ... Valve housing, 2 ... Spool 3 ... Sleeve, 4 ... Stopper pin 6 ... Drive shaft, 7 ... Measuring section 7-1 ... Internal tooth member, 7-2 ... External tooth member 16 ... … Switching valve, 19 …… Inlet port 20 …… Auxiliary fluid port, 21 …… Right outlet port 22 …… Left outlet port, 23 …… Drain port 53 …… Internal space, 75 …… Auxiliary equipment

Claims (1)

(57) [Claims] Claim: What is claimed is: 1. A housing having an inlet port, an outlet port to a steering cylinder, an internal tooth member provided in the housing, and an external member which is in the internal tooth member and meshes therewith to rotate and revolve. A measuring unit having a tooth member,
A switching valve for controlling the flow of fluid between each of the ports and the metering unit, the switching valve having a spool, a sleeve, and a drive shaft disposed in the spool and driving the spool, the sleeve and the external tooth member in an associated manner. And a pump for supplying hydraulic oil to the inlet port, in an all-hydraulic steering system, an auxiliary fluid port for supplying fluid to auxiliary equipment in the housing, an internal space in which the drive shaft of the spool is arranged, and an external space. And a drain port that communicates with each other, and regardless of the position of the switching valve, the inlet port and the auxiliary fluid port communicate with each other with or without the outlet port, and almost all of the pump discharge oil is the auxiliary fluid. An all-hydraulic steering system characterized by being supplied to a port.