JPH032466Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to an all-hydraulic power steering system with a simplified structure, and particularly to improvements in control valves.

(Conventional technology and its issues) Conventional fully hydraulic power steering devices can be roughly divided into:
Two types are available: EATON type and TRW type.

The EATON model consists of a rotary valve, a trochoidal gear pump, and a commutator.The rotary valve is combined with a sleeve, and its clearance and concentricity are controlled at four locations in the cylindrical part (valve housing). The commutator is a simple mechanism, although it requires a certain diameter (inner diameter, inner and outer diameters of the sleeve, and valve diameter).

On the other hand, the TRW type consists of a slide valve, a trochoidal gear pump, and a commutator, and although there are only two cylindrical parts (valve housing inner diameter and valve diameter) that require precision control of clearance and concentricity, the commutator has become a complex mechanism.

Note that Japanese Utility Model Application Publication No. 51-123524 discloses a hydraulic controller having a structure in which a commutator valve is linked to a spool that is displaced in the axial direction as the input shaft rotates. According to this, although the structure around the valve is relatively simple, the number of parts is large because a mechanism consisting of a combination of pins and long holes is used to convert the rotational displacement of the input shaft in the axial direction. At the same time, there was a problem in that the accuracy was lowered due to looseness between the parts.

The object of the present invention is to solve these conventional problems and provide a fully hydraulic power steering device that is simple in structure, easy to process, and highly accurate.

(Means for Solving the Problems) To achieve this, in the present invention, a valve spool is screwed onto the input shaft connected to the steering input side via a helical screw, a commutator is engaged with this spool, and a metering is applied to the commutator. While forming an oil hole group that communicates the oil chamber of the pump with the annular port of the valve housing, a dowel pin is installed in a notch groove formed in the axial direction at the end of the input shaft so as to have a predetermined clearance in the circumferential direction. The end of the dowel pin is held in a groove formed in the axial direction of the spool, and a plate-shaped reaction spring is housed in the inner hole formed in the end of the input shaft to connect the dowel pin and the input shaft. and the drive shaft of the metering pump was connected to a dowel pin.

(Function) In the above configuration, the valve spool is screwed into a helical screw provided around the input shaft and moves in the axial direction to generate valve deviation, and two sets of oil holes formed in the commutator that engage with the valve spool Via
A passage from the annular port of the valve housing communicates with an oil chamber of the metering pump.

When the rotation of the input shaft is transmitted to the spool, a reaction force acts directly on the input shaft based on the deformation of the plate-shaped reaction spring connected to the dowel pin. At this time, the reaction force is due to the sliding resistance of the helical screw. There is no such thing as increasing Furthermore, since the drive shaft of the metering pump is connected to the dowel pin, no unnecessary external force is applied to the spool due to its rotation. For these reasons, the spool operates extremely smoothly.

On the other hand, the dowel pin held on the spool is connected to the input shaft via a reaction spring housed in an inner hole formed at the end of the input shaft, and the drive shaft of the metering pump is connected to this dowel pin, so that the overall As a result, the axial dimension becomes extremely small. In addition, the relative rotation between the input shaft and the dowel pin is regulated at the position where the dowel pin contacts the axial notch groove at the end of the input shaft. This contributes to shortening the dimension in this direction.

(Example) Examples of the present invention will be described below based on the drawings.

As shown in FIGS. 1 and 2, the valve housing 1 rotatably supports an input shaft 3 in its inner hole via a holder 2 fixed at one end, and has a sidewall at the other end. A metering pump 5 is fixedly installed via a plate 4.

The metering pump 5 has a valve housing 1
an outer rotor 6 fixedly attached to the outer rotor 6;
A trochoid type gear pump is constructed by the inner rotor 7 that meshes with the inner teeth of the inner rotor 7.
Pin 1 of drive shaft 9 is attached to spline 8 of
0 is engaged, and the drive shaft 9 holds the dowel pin 12 in a groove 11 formed at the end on the input shaft 3 side.

On the other hand, the valve housing 1 and the side plate 4
A commutator 13 is provided between the valve housing 1 and the valve housing 1.
A spline 15 is provided on a part of the outer periphery of the cylindrical portion extending inward.
is engraved.

The input shaft 3 has a helical screw 1 on a part of its outer periphery.
6 and an inner hole 17 therein, one end is connected to a handle (not shown) serving as a steering input member, and the other end is provided with an axially long notched groove 18 facing each other. The cutout groove 18 holds the dowel pin 12 and has a clearance δ on both sides. Further, a reaction force spring 19 is provided in the inner hole 17, and the reaction force spring 19 is connected to the arm portions 2 on both sides of the tip.
At 0, the dowel pins 12 are half-circled, overlapped and integrated, and inserted into a groove carved in the bottom of the inner hole 17.

A valve spool 21 is closely sliding on the valve housing 1, and the valve spool 21 is
A helical gear 23 provided at one end of the inner hole 22 engages with the helical screw 16 of the input shaft 3, and a spline 24 provided at the other end engages with the spline 15 of the commutator 13. In addition, grooves 11' cut in the axial direction insert and hold both ends of the dowel pin 12.

Next, the oil passage system will be explained. Communicator 1
3 _{, as shown in} FIG _{. 6} is a long hole in the centripetal direction,
The oil hole groups E ₁₁ to _{E 16} form long grooves in the centrifugal direction. Further, a group of oil holes F ₁ to _{F 7} are bored in the side plate 4 on the same pitch circle D as the commutator 13, and these holes communicate with an oil chamber (not shown) of the metering pump 5.

On the other hand, the valve housing 1 has 10 annular ports G ₁ , G ₂ , M ₁ ,
C ₁ , T ₁ , P ₁ , T ₂ , C ₂ , M ₂ , P ₂ and six passages 25 _P , 25 _T , 25 _c1 , 25 _c2 , 25 _M1 , 25 _M2 are provided. Annular ports P ₁ and P ₂ are passage 2
5 _P to pump P, annular ports T ₁ and T ₂ to tank T via passage 25 _T , annular ports C ₁ and C ₂ to pressure chamber A of power cylinder C via passages 25 _c1 and 25 _c2 . and B, the annular ports M ₁ and M ₂ are connected to the oil hole groups E ₁ to E ₆ and E ₁₁ to E ₁₆ of the commutator 13 via the passage 25 _M1 , the annular port C ₁ and the passage 25 _M2 , and the annular port G ₂ . are connected to each other.

Further, the valve spool 21 is provided with four annular ports H ₁ to H ₄ from the metering pump side, and when the valve spool 21 is in the neutral state, the annular ports H ₁ and H ₄ are connected to the annular ports of the valve housing 1. occlude C ₁ and C ₂ and also annular port H ₂
and _H3 communicate with the annular ports _T1 and _P1 and _P1 and _T2 , respectively.

Next, the effect will be explained.

With a load on power cylinder C,
When the input shaft 3 is rotated to the left by turning the handle to the left as shown in the figure and FIG. However, the valve spool 21 remains in the neutral position and its displacement in the rotational direction is restricted until a hydraulic pressure commensurate with the load is generated, the metering pump 5 is activated, and the valve spool 21 is driven via the drive shaft 9 and dowel pin 12. As a result, the input shaft 3 rotates by twisting the arm portion 20 of the reaction spring 19, creating a phase difference with respect to the valve spool 21. The reaction force of the reaction force spring 19 at this time is transmitted from the input shaft 3 to the driver via the steering wheel as a steering reaction force.

The valve spool 21 has a helical gear 23
The input shaft 3 is screwed into the helical screw 16 of the input shaft 3, which rotates with a phase difference, but as mentioned above, the displacement in the rotational direction is restrained, so the valve is axially displaced to the left as shown by the arrow. deviation, annular port H ₂
and H ₃ occlude annular ports T ₁ and P ₁ ,
The annular ports H ₁ and H ₄ communicate with the annular ports M ₁ and C ₁ and T ₂ and C ₂ , respectively.
Therefore, the hydraulic oil is led from the pump P to the annular port P ₂ via the passage 25 _P , and then passes through the annular port M ₂ , the passage 25 _{M 2} , and the annular port G ₂ to the commutator 13 .
oil hole group E ₁₁ to _{E 13} , oil hole group F ₂ of side plate 4
~ _F4 is introduced into the oil chamber of the metering pump 5.

The hydraulic oil metered by the metering pump 5 passes through the oil hole group F ₅ to _{F 7} of the side plate 4 and the oil hole group E ₄ to E ₆ of the commutator 13 to the annular port G ₁ of the valve housing 1. Guided by passage 25 _M
1 , through the annular ports M ₁ , H ₁ , C ₁ and through the passage 25 _c1 to the pressure chamber A of the power cylinder C, generates the required output, and passes through the link member 26.
Turn the wheels (not shown) to the left.

The other pressure chamber B of the power cylinder C is the return pressure, which is led from the passage 25 _c2 to the annular port C ₂ , via the annular ports H ₄ and T ₂ and then through the passage 25 _T to the tank T.
will be collected.

On the other hand, the pressure oil introduced from the annular port _G2 of the valve housing 1 causes the metering pump 5 to
The inner rotor 7 rotates in the same direction as the input shaft 3 and transmits rotation to the valve spool 21 via the drive shaft 9 and dowel pin 12 to eliminate the phase difference with the input shaft 3 and valve spool deviation. The valve spool 21 follows the input shaft 3, which performs inner feedback and continues to rotate as the handle rotates, until the input shaft 3 stops rotating. In this way, the required turning of the wheels takes place.

Contrary to the above, when the handle is turned to the right, the valve spool 21 is displaced to the right and switches the oil path, and the meter is passed from the annular groove M ₁ and G ₁ side to the oil hole group E ₁ to _{E 6} . Hydraulic oil measured by ring pump 5,
The oil is fed under pressure to the pressure chamber B of the power cylinder C through the annular grooves G ₂ and C ₂ and the passage 25 _c2 from the group of oil holes E ₁₁ to E ₁₆ to turn the wheel to the right.

In addition, when the hydraulic pressure stops, as shown in Fig. 2, when the handle is turned to the right, the input shaft 3 rotates by δ and comes into contact with the dowel pin 12 at the side of the notched groove 18, causing the dowel pin 12 and the drive shaft to rotate. Since the inner rotor 7 is rotated via the metering pump 9, the metering pump 5 becomes a hydraulic motor and drives the power cylinder C.

(Effects of the invention) As explained above, according to the invention, the valve spool is screwed into the helical screw provided around the input shaft and displaced in the axial direction to cause valve deviation, and the commutator that engages with the valve spool Two sets of oil holes are provided in the valve housing, and the passage from the annular port of the valve housing communicates with the oil chamber of the metering pump, which simplifies the structure and facilitates machining. effective.

Further, according to the present invention, the axial dimension of the device can be significantly reduced.

In addition, since this invention uses a helical screw to convert the rotational displacement of the input shaft into axial displacement,
The structure of this direction changing mechanism is also simplified, the number of parts is reduced, and there are no parts that cause looseness, so there is an advantage that high accuracy can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing an embodiment of the present invention when it is in neutral, Fig. 2 is a top view showing the vicinity of the dowel pin in Fig. 1, and Fig. 3 is a side sectional view showing the left turn as shown in Fig. 1. , FIG. 4 is a front view of the commutator viewed from the input shaft. 1...Valve housing, 3...Input shaft, 4...
...Side plate, 5...Metering pump,
7...Inner race, 9...Driveshaft,
10... Pin, 11... Groove, 12... Dowel pin, 13... Commutator, 14... Flange portion, 15... Spline, 16... Helical screw, 17... Inner hole, 18... Notch groove, 19 ... Reaction spring, 21 ... Valve spool, 23 ... Helical gear, 24 ... Spline, 25 ... Valve spool groove, C ₁ , C ₂ , G ₁ , G ₂ , H ₁ ~ H ₄ , M ₁ ，
M ₂ , P ₁ , P ₂ , T ₁ , T ₂ ... Annular port, E ₁ to _{E 6} ,
E ₁₁ to E ₁₆ ... Oil hole group of commutator, F ₁ to F ₇ ...
Oil holes on the side plate.

Claims (1)

[Scope of utility model registration request] A valve spool is screwed onto the input shaft connected to the steering input side via a helical screw, a commutator is engaged with the spool, and an oil valve is connected to the commutator to communicate the oil chamber of the metering pump with the annular port of the valve housing. While forming the hole group, a dowel pin is arranged in a notch groove formed in the axial direction at the end of the input shaft so as to have a predetermined clearance in the circumferential direction, and the end of the dowel pin is attached to the spool in the axial direction. A plate-shaped reaction force spring that is held between the formed groove and connects the dowel pin and the input shaft is housed in the inner hole formed at the end of the input shaft, and the drive shaft of the metering pump is connected to the dowel pin. A fully hydraulic power steering device characterized by: