JP3490163B2 - Power steering device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering apparatus provided with a rotary control valve for controlling the flow of a fluid by the relative rotational displacement of a rotary spool and a sleeve. 2. Description of the Related Art As a conventional power steering apparatus, for example, there is one shown in FIG. Knuckle arms 5 respectively attached to left and right tires 51 and 52
3 and 54 are connected to a rack shaft 57 via side rods 55 and 56. The rack formed on the shaft of the rack 57 meshes with a pinion formed on a pinion shaft 60 rotated by a steering shaft 59 integrally connected to the handle H. Further, a cylinder piston 62 that is incorporated in the power cylinder PC so as to be movable in the axial direction is integrally attached to the rack shaft 57. [0003] The steering shaft 59 and the pinion shaft 6
Between 0, a control valve 63 is provided. The control valve 63 is
The first is composed of a series of connected variable throttle sections 63a and 63b.
A variable throttle unit 63c, 63 also connected in series with the valve set
and a second valve set made of d. In accordance with the rotation of the handle H, the variable throttle portions 63a and 63b change their opening degrees in opposite directions. Similarly, according to the rotation of the steering wheel, the variable throttle portions 63c and 63d also change their opening degrees in opposite directions. Then, the first valve set and the second valve set have opposite opening degree changes. Variable throttle unit 63a
The upstream inlet port 69 is connected to the pump P, and the downstream side of the variable throttles 63b and 63d is connected to the tank T. Further, the variable throttle units 63a and 63b
Is connected to the first cylinder chamber 61a of the power cylinder PC via the cylinder passage 64, and the second output port 71 of the intermediate portion between the variable throttle portions 63c and 63d is connected to the cylinder passage 65. And is connected to the second cylinder chamber 61b of the power cylinder PC via the. Further, the first cylinder variable throttle 6 is provided in the cylinder passage 64.
6 and a second cylinder variable throttle 67 in the cylinder passage 65.
Is provided. These cylinder variable throttles 66 and 67 are connected to an electronic control device 68, and change their opening in accordance with a signal from the electronic control device 68. Next, the operation of this conventional example will be described. When the handle H is turned to the right, the variable throttles 63b and 63c
And the variable throttle portions 63a and 63
It is assumed that the opening degree of d becomes small. Therefore, the oil discharged from the pump is guided to the variable throttle portion 63c side, and is also guided to the second cylinder chamber 61b through the cylinder passage 65. At the same time, the pressure oil is guided to the port 70 through the cylinder passage 64 toward the first cylinder chamber 61a, and is also guided to the tank T by flowing toward the variable throttle valve 63b.
That is, the hydraulic pressure on the second cylinder chamber 61b side increases and the hydraulic pressure on the first cylinder chamber 61a side decreases, so that the cylinder rod 62 moves leftward in the drawing, and the side rods 55 and 56 and the knuckle arm 53 , 54, an assist force is applied to the tires 51, 52 in the right direction in the figure. When the handle H is turned to the left, on the contrary, the opening of the variable throttles 63a and 63d increases, and the opening of the variable throttles 63b and 63c decreases.
The application of the assist force in the left direction in the figure is the same. When the handle H is at the neutral position, the pump-side variable throttle portions 63a and 63c and 63b and 63d maintain the same opening. Therefore, the discharge oil of the pump communicates with the tank via the first valve set and the second valve set, and the same oil pressure is guided to the chambers 61a and 61b.
The tires 51 and 52 keep running straight. Here, when the steering wheel is neutral, the opening of the cylinder variable throttles 66 and 67 is kept to a minimum by the electronic control unit 68. At this time, the cylinder chambers 61a and 61b are filled with the same pressure and low hydraulic pressure. And the tire side 51, 52
When any external force is applied from the
6, 67, this force can be attenuated and straight running can be stabilized. When steering the steering wheel H,
The degree of opening of the cylinder variable throttles 66 and 67 is set to such an extent that the response of the cylinder 61 to steering of the steering wheel H does not deteriorate.
In addition, adjustment is made so as to obtain a damping effect on external force. As described above, in the power steering apparatus of the conventional example, the opening of the first and second cylinder variable throttles 66 and 67 is adjusted by the electronic control unit 68 according to the traveling state. In the above-described conventional power steering apparatus, the opening of the first and second variable cylinder throttles 66 and 67 is adjusted by an electronic control unit 68. Therefore, the entire apparatus becomes complicated and costly, and there is also a problem in reliability because electric signals are used. An object of the present invention is to provide an inexpensive and highly reliable power steering device without using an electric signal. According to the present invention, a sleeve is provided around a rotary pool connected to a steering wheel, and the relative position between the rotary pool and the sleeve changes in accordance with the steering of the steering wheel. It is assumed that a power steering device controls fluid guided to a cylinder. On the premise of the power steering device described above, the present invention relates to a sleeve, which is located on the diameter line of the sleeve and connected to a pump and a pair of inlet ports, and located on one side based on the pair of inlet ports, and A pair of opposing first output port grooves, located on the other side with respect to the pair of inlet ports, and a pair of opposing second output port grooves, positioned approximately 90 degrees offset from the inlet port; First and second relay ports facing each other, a first passage groove located on both sides of the first relay port, and a second passage groove located on both sides of the second relay port are formed. Are always in communication with the pair of inlet ports, and when the handle is neutral, a pair of link grooves connecting the inlet port and the output port grooves on both sides thereof are located on both sides of the pair of link grooves. And four return grooves that communicate with the output ports when the handle is neutral and return the fluid to the tank; a first communication groove that connects the first relay port to the first passage grooves adjacent to the first relay port when the handle is neutral; A first communication passage connecting the first relay port to the pair of first output port grooves, forming a second communication groove communicating the second relay port with the second passage groove on both sides thereof at the time of neutralization; ,
A second linking passage connecting the second relay port to the pair of second output port grooves; a first cylinder passage connecting the first passage groove to the first cylinder chamber of the power cylinder; and a second cylinder groove connecting the second passage groove to the power cylinder. A second cylinder passage connected to the second cylinder chamber is provided, and when the relative position of the rotary pool and the sleeve changes by turning the steering wheel, the first output port groove or the second output port groove depends on the relative position. The opening of either one of the and the inlet port increases,
The degree of opening between the other output port groove and the return groove increases, and the pump discharge fluid is guided to either the first link passage or the second link passage, and the fluid in the other link passage is guided to the return passage. A first cylinder throttle formed by combining the first relay port, the first passage groove, and the first communication groove in accordance with turning of the handle; and a second relay port, a second passage groove, and a second The second cylinder throttle, which is configured in combination with the communication groove, is characterized in that its opening is increased. In the power steering apparatus according to the present invention, when the steering wheel is in the neutral position, a low-pressure fluid having the same pressure is guided to both chambers of the power cylinder. Further, since the opening degrees of the first and second cylinder variable throttles are minimized, straight running can be stabilized even when an external force is applied.
When the steering wheel is steered, the fluid from the pump is guided to one of the first and second cylinder variable throttles according to the steering of the steering wheel, and the first and second variable cylinder throttles are driven by the steering wheel. Since the degree of opening is increased in accordance with the condition, the amount of oil flowing into the power cylinder is increased, and the steering performance of the steering wheel and the followability of the power cylinder can be improved. In the embodiment of the present invention shown in FIGS. 1 to 5, a steering shaft 2 is inserted into a casing 1, and the steering shaft 2 and a pinion shaft 3 are connected by a torsion bar 4. . A rotary spool 5 is formed integrally with the steering shaft 2, and a sleeve 6 is provided around the rotary spool 5.
Are fitted so as to be relatively rotatable, and the sleeve 6 is rotated integrally with the pinion shaft 3. The rotary spool 5 and the sleeve 6 constitute a rotary control valve. Further, the pinion 3 a formed on the pinion shaft 3 is engaged with a rack 7 a formed on the rack shaft 7. As shown in FIG. 2, a pair of input ports 8 and 9 are formed in the sleeve 6 at positions facing each other on a diameter line of the sleeve. In addition, in the vicinity of both sides of each of the input ports 8 and 9, at positions symmetrical with respect to the input ports 8 and 9,
Output port grooves 10, 11 and 12, 13 are formed. These first output port grooves 10 and 12 are located at positions facing each other on the sleeve diameter line, and the second output port grooves
1 and 13 are positioned opposite each other on the sleeve diameter line. The rotary spool 5 is formed with a pair of linking grooves 25 and 26 at positions facing each other on the diameter line. When the handle is in the neutral position, that is, when the rotary spool is in the neutral position shown in FIG.
0 and 11 communicate with each other, and the input port 9 and the output port grooves 12 and 13 communicate with each other via the linkage groove 26. The rotary spool 5 has four return grooves 27-30.
The return grooves 27 to 30 are always in communication with a return hole 31 formed in the rotary spool 5, while the return hole 31 is connected to a return passage 32 connected to the suction port of the pump P. . At the time of the neutral state shown in FIG. 2, the return grooves 27 to 30 respectively correspond to the output port grooves 10 to 1.
It communicates with 3. Further, the input port 8 is provided on the sleeve 6.
A first relay port 18 and a second relay port 17 facing each other are formed at positions shifted from each other by approximately 90 degrees.
The first passage grooves 37 and 38 and the second passage grooves 35 and 36 are formed in the vicinity of both sides of the relay ports 17 and 18 symmetrically with respect to the relay ports 18 and 17 respectively. The passage grooves 35 and 37 are located at positions facing each other on the sleeve diameter line, and the passage grooves 36 and 38 are also located at positions facing each other on the sleeve diameter line.
The rotary spool 5 has the link grooves 25, 2
6 and a first communication groove 34 and a second communication groove 33 facing each other are formed at positions shifted from each other by approximately 90 degrees. The second communication groove 33 is always in communication with the second relay port 17 and, at the time of the neutral state shown in FIG.
7 communicates with the second passage grooves 35 and 36. Similarly,
The first communication groove 34 communicates with the first relay port 18 and, when in the neutral state shown in FIG.
Are communicated with the first passage grooves 37 and 38. The input ports 8 and 9 communicate with each other via an input passage 14, and the input passage 14 is connected to a discharge port of the pump P. Also, the first
First output ports 10 a, 12 of output port grooves 10, 12
a communicates via the first linking passage 15, and the first linking passage 15 communicates with the first relay port 18.
Similarly, the first output port 1 of the second output port grooves 11 and 13
1 a and 13 a communicate with each other via a second link passage 16, and the second link passage 16 communicates with a second relay port 17. Further, the first passage grooves 37, 38
While communicating with the first cylinder chamber 23a of the power cylinder PC via the cylinder passage 24, the second passage grooves 35, 36
Is connected to the power cylinder PC via the second cylinder passage 22.
And the second cylinder chamber 23b. FIG. 3 specifically shows each throttle of the rotary type control valve described above on the same sectional view as FIG. More specifically, the link groove 25 and the first output port groove 1
The stop formed by 0 is a1 and the stop formed by the linkage groove 26 and the first output port groove 12 is a2. The apertures a1 and a2 have the same characteristics, and the apertures a1 and a2 together constitute a variable aperture section A. Similarly, the stop c1 constituted by the link groove 25 and the second output port groove 11, the link groove 26 and the second
It is assumed that the stop c2 formed by the output port groove 13 constitutes a variable stop C. The variable throttle portions A and C maintain the same opening when the steering wheel is neutral. When the steering wheel is turned to the right, the opening of the variable throttle portion A decreases and the opening of the variable throttle C increases. Conversely, when the steering wheel is turned to the left, the opening of the variable throttle portion A increases and the opening of the variable throttle C decreases. As described above, the variable throttle portions A and C have the same change in the opening degree although the opening degree change is opposite. The stop formed by the second output port groove 11 and the return groove 28 is denoted by b1, and the stop formed by the second output port groove 13 and the return groove 30 is denoted by b2. The apertures b1 and b2 have the same characteristics, and the aperture b
It is assumed that 1 and b2 together form a variable aperture section B. Similarly, the stop d1 formed by the first output port groove 10 and the return groove 27 and the stop d2 formed by the first output port groove 12 and the return groove 29 corresponding thereto constitute a variable stop D. It shall be. The variable throttle portions B and D maintain the same opening when the steering wheel is neutral. When the steering wheel is turned to the right, the opening of the variable throttle section B decreases, and the variable throttle D
When the steering wheel is turned to the left, the opening of the variable throttle section B increases, and the opening of the variable throttle D decreases. Thus, the variable diaphragm portions B and D
Although the change in the opening degree is opposite, the characteristic of the change in the opening degree is the same. On the other hand, the stop formed by the second communication groove 33 and the second passage groove 35 is designated by e1, and the stop constituted by the second communication groove 33 and the second passage groove 36 is designated by e2. The apertures e1 and e2 have the same opening when the steering wheel is neutral, and the apertures e1 and e2 together constitute a second cylinder variable aperture E. Similarly, the stop formed by the first communication groove 34 and the first passage groove 37 is f1 and the stop formed by the first communication groove 34 and the first passage groove 38 is f2. The apertures f1 and f2 have the same opening when the steering wheel is neutral, and the apertures f1 and f2 together constitute a first cylinder variable aperture F. The variable throttle units A, B, C, and D described above, and the cylinder variable throttle E,
F is shown in FIG. 4 as an equivalent circuit diagram. Then, as can be seen from FIG. 4, the first valve set is configured by the variable throttle portions A and B.
The variable throttle sections C and D constitute a second valve set. Next, the operation of the power steering device will be described. When the handle is in the neutral position, the relative positions of the rotary spool 5 and the sleeve 6 are as shown in FIGS. At this time, the discharge oil of the pump P guided to the input ports 8 and 9 is guided to the linking grooves 25 and 26, and the output port grooves 10, 11, and 12, via the throttles a1, a2 and c1, c2. Flow into 13. In addition,
At this time, the apertures a1, a2 and c1, c2 all keep the same opening. Further, the output port grooves 10, 11
The oil that has flowed into the pumps 12 and 13 flows into the return grooves 27 to 30 via the throttles b1 and b2 and d1 and d2, and is returned to the return passage 32 through the return hole 31. At this time, the apertures b1, b2 and d1, d2 all keep the same opening. At this time, the oil in the output port grooves 10, 11 and 12, 13 is guided to the relay ports 17 and 18 through the first and second link passages 16 and 15. Then, the oil guided into the communication grooves 33 and 34 is
Via the apertures e1, e2 and f1, f2, the passage groove 35,
36 and 37, 38. At this time, the throttles e1 and e2 and f1 and f2 all have the same opening, and the cylinder variable throttles E and F have the minimum opening. Then, the oil is guided to the cylinder chambers 23a and 23b through the cylinder passages 22 and 24. This operation will be described with reference to an equivalent circuit shown in FIG.
When the steering wheel is neutral, the openings of the variable throttle portions A and C are the same, and the openings of the variable throttle portions B and D are also the same. Therefore, the oil discharged from the pump passes through the first valve set including the variable throttle portions A and B connected in series and the second valve set including the variable throttle portions C and D similarly connected in series. To the tank T. At this time, the chamber 23 of the cylinder 23
Since the pressures in a and 23b are the same, straight running is maintained without performing steering assist. Also, since the low-pressure hydraulic pressure is satisfied, even if any external force is applied from the tire side, the first and second cylinder variable throttles F and E can attenuate this force and stabilize straight running. it can. Next, when the handle is turned rightward from the handle neutral position, the rotary spool 5 rotates in the direction of arrow K as shown in FIG. 5, and the relative positions of the rotary pool 5 and the sleeve 6 are as shown in FIG. Changes to At this time,
The apertures of the apertures c1 and c2 increase and the apertures a1
And the opening degree of a2 becomes small. Therefore, a large amount of the pump oil guided to the link grooves 25 and 26 flows into the second output port grooves 11 and 13 according to the openings of the throttles c1 and c2. Further, since the openings of the throttles b1 and b2 are small, the oil flowing into the output port grooves 11, 13 is discharged to the second port.
It is guided to the second communication groove 33 via the connection passage 16. At this time, although the opening degree of the aperture e1 is small,
Since the aperture e2 is large, the opening degree of the second cylinder variable aperture E is eventually large. In other words, the oil in the second communication groove 33 passes through the second cylinder passage 22, and more pressure oil is guided to the second cylinder chamber 23b than when the handle is in a neutral state. At the same time, since the openings of the throttles d1 and d2 are large, the oil in the first output port groove 10 is removed from the return groove 2
7 and flows into the return hole 31. Since the throttle f2 is now large, the first cylinder chamber 23
the oil in the first cylinder passage 24 → throttle f2 → first communication groove 34 → first connection passage 15 → first output port groove 10,
12 → stops d1 and d2 → pass through return grooves 27 and 29 and are guided to return hole 31. Therefore, the hydraulic pressure in the second cylinder chamber 23b increases and the hydraulic pressure in the first cylinder chamber 23a decreases, and the cylinder rod moves to assist steering. When the steering wheel is turned to the left, the operation is the same as described above, and a detailed description thereof will be omitted. This operation will be described with reference to an equivalent circuit shown in FIG.
When the steering wheel is turned to the right, the opening of the variable throttle portion A decreases and the opening of the variable throttle portion C increases. Accordingly, the oil discharged from the pump is guided to the variable throttle portion C side, and is also guided to the cylinder variable throttle E through the second link passage 16. Here, the second cylinder variable throttle E
Since the opening degree of the handle is increased according to the degree of cutting of the handle, it flows into the second cylinder chamber 23b through the second cylinder passage 22. At the same time, the opening of the first variable throttle section D becomes smaller and the opening of the variable throttle section B becomes larger. Further, since the opening degree of the first cylinder variable throttle F increases according to the degree of turning of the steering wheel, the first cylinder variable throttle F passes through the first cylinder passage 24 and the first linkage passage 15 to the first output ports 10a and 12a. Be guided. Then, it is guided to the tank T via the variable throttle section B. That is, the hydraulic pressure on the side of the second cylinder chamber 23b increases, and the hydraulic pressure on the side of the first cylinder chamber 23a decreases.
The inner cylinder rod moves to the left in the figure to apply an assist force to the steering of the steering wheel. When the handle H is turned to the left, on the contrary, the openings of the variable throttle portions A and D increase, and the openings of the variable throttle portions B and C decrease.
The same applies to the case where an assist force is applied to steering to turn the steering wheel to the left. As described above, when the steering wheel is neutral,
The first and second cylinder variable throttle portions E and F are minimized, and their opening increases according to the degree of steering of the handle. Therefore, when the steering wheel is neutral, even if an external force is applied from the tire, straight running can be stabilized, and when the steering wheel is turned, the power cylinder P
The amount of oil flowing into C becomes large, and the steering performance of the steering wheel and the followability of the power cylinder can be improved. In this way, without using electrical signals, inexpensive, and
Reliability can be improved. The opening degree characteristics of the throttle portions E and F may be determined in consideration of the damping effect when some external force is applied from the tire side, and the steering characteristics of the steering wheel and the followability of the power cylinder. Further, in this embodiment, a rack and pinion type power steering device has been described, but it goes without saying that the present invention is also applied to a worm nut type power steering device. According to the present invention, an inexpensive and highly reliable power steering apparatus can be provided without using an electric signal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a power steering device according to an embodiment of the present invention. FIG. 2 is a view showing the rotary valve when the steering wheel is at a neutral position in the power steering apparatus according to the embodiment. FIG. 3 is a diagram specifically showing each throttle of the rotary valve on the same sectional view as FIG. 2; FIG. 4 is an equivalent circuit diagram of the power steering device according to the embodiment. FIG. 5 is a diagram showing the rotary valve when the steering wheel is turned to the right in the power steering device of the embodiment. FIG. 6 is an equivalent circuit diagram of a conventional power steering device. [Description of Symbols] 5 Rotary spool 6 Sleeve 8, 9 Input port 10, 12 First output port groove 11, 13 Second output port groove 15 First link passage 16 Second link passage 17 Second relay port groove 18 First Relay port groove 22 Second cylinder passage 24 First cylinder passage 25, 26 Coupling groove 33 Second communication passage 34 First communication passage PC Power cylinder 23a First cylinder chamber 23b Second cylinder chamber

Claims (1)

(57) [Claims 1] A sleeve is provided around a rotary pool connected to a steering wheel, and the relative position between the rotary pool and the sleeve changes according to the turning of the steering wheel, so that the power cylinder is connected to the power cylinder. In the power steering device for controlling the fluid to be guided, the sleeve has a pair of inlet ports located on its diameter line and connected to the pump, and a pair of inlet ports located on one side based on the pair of inlet ports and opposed to each other. A first output port groove, and a pair of second output port grooves which are located on the other side with respect to the pair of inlet ports and which are opposed to each other, and which are located at a position shifted from the inlet port by substantially 90 degrees and are opposed to each other. First and second relay ports, and first passage grooves located on both sides of the first relay port;
A second passage groove located on both sides of the second relay port is formed, and the rotary pool is always in communication with the pair of inlet ports, and when the handle is neutral, the inlet port and the output port groove on both sides thereof are connected. A pair of linking grooves, four return grooves which are located on both sides of each of the pair of linking grooves, communicate with the output ports when the handle is neutral, and return the fluid to the tank.
Forming a first communication groove communicating the relay port with the first passage groove on both sides thereof, and a second communication groove communicating the second relay port with the second passage groove on both sides thereof when the handle is neutral; A first linking passage connecting the first relay port to the pair of first output port grooves, a second linking passage connecting the second relay port to the pair of second output port grooves, and a first link groove of the power cylinder. A first cylinder passage connecting to the first cylinder chamber and a second cylinder passage connecting the second passage groove to the second cylinder chamber of the power cylinder are provided, and the steering wheel is steered to adjust the relative position of the rotary pool and the sleeve. When it changes,
Depending on this relative position, the first output port groove or the second output port groove
The opening degree between one of the output port grooves and the inlet port increases, and the opening degree between the other output port groove and the return groove increases, so that the pump discharge fluid flows into either the first link passage or the second link passage. While being guided to one side, the fluid in the other connecting passage is guided to the return passage, and further, the first relay port, the first passage groove, and the first communication groove are configured in accordance with the turning of the handle. A power steering device characterized in that the opening degree of the first cylinder throttle and the second cylinder throttle similarly configured by combining the second relay port, the second passage groove, and the second communication groove are large.