JPS606823B2 - power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering device configured to eliminate backlash between gears of a differential gear mechanism that switches control valves of the power steering device.

The applicant has proposed a number of power steering devices equipped with differential gear mechanisms, which have enabled power steering with excellent responsiveness. Since it is formed from a group, play between the gears is likely to occur, which is a problem.

An example (Japanese Patent Laid-Open No. 51-100542) will now be explained. In Figures 1 and 2, 1 is the cylinder no.
2 is a differential machine housing, and 3 is an input shaft connected to a handle (not shown). 4 is a sector gear, which is connected to the Bittman arm of the steering wheel (not shown).Finally, the sector gear 4 rotates (output) in proportion to the rotation (input) of the input shaft 3, and rotates the steering wheel. Turn the wheel.

A piston 5 that meshes with a sector gear 4 is disposed within the cylinder housing 1, and defines working chambers A and B on both sides. The cylindrical screw shaft 6 is attached to this piston 5.
The torsion bar 9 is screwed into the inner peripheral surface of the
It is connected to the input shaft 3 via. A planetary gear mechanism is used as the differential gear mechanism C, and Sangya turtles a and turtle b are symmetrically carved on the peripheral surfaces of the input shaft 3 and screw shaft 6, respectively, with a rotatable disk 110 in between. , and a plurality of planet gear turtles 2a, 12b that mesh with these are symmetrically arranged on both sides of the disk cup Q using pins 13.

Each of the planet gear turtles 2a and 2b is similarly engaged with a ring gear 84a and a ring gear 4b, and one ring gear turtle 4a, which is rotatably supported, is connected to the spool 16 of the control valve turtle 7 via a rod 15. Other ring gear turtle 4
b is fixed to the differential horizontal housing 2. As the spool turtle 6 moves, the control valve 17 connects the annular boats P, T and M as appropriate, and selectively supplies pressure fluid to the working chamber A or B defined within the cylinder housing 1. . Then, the steering wheel is turned to rotate the input shaft 3. Since the sector gear connected to the steering wheel before turning is fixed due to ground resistance, the piston 5 and screw shaft 6 that mesh with it are stationary, and one sector gear 11b is also fixed in the same way as the ring gear 14b. There is. Therefore, due to the rotation of the sun gear 11a of the input shaft 3, the planet gear 12a rotates on its own axis without revolving around the planet gear, which rotates the ring gear a and rotates the planet gear 12a.
Transfer 6. The control valve 17 switched in this manner supplies pressurized fluid from the hydraulic pump to one of the working chambers A or B defined within the piston 5. At the same time, the rotational force (steering force) of the input shaft 3 is transmitted to the other screw shaft 6 while changing the torsion bar 9, so that the Sangya blade lb is the same as the Sangya blade a with a slight phase lag. It starts rotating at the rotational speed.
Therefore, the planet gear tortoise 2a, which had been performing only a rotational motion, simultaneously rotates and revolves in parallel with the other planet gears 12b, and as a result, the ring gear 14a is stopped at that position. In other words, the control valve g7 is maintained in the switched state, and pressurized fluid continues to be supplied into the working chamber until the input shaft 3 stops.By the rotation of the screw shaft 6, the piston 5 that is engaged with it shifts by a pitch proportional amount. However, this transition operation is performed smoothly by the pressure fluid supplied to the working chamber A or B, and the operator can rotate the sector gear 4 and turn the steering wheel with extremely little force. While the input shaft 3 is rotating, the piston 5 is moved by the working fluid by an amount proportional to this pitch and follows.
Naturally, when input shaft 3 is stopped, Sanghya 1
1a also stops, but the other sangya 11b' rotates by an amount equivalent to the displacement applied to the torsion bar 9 and then stops.

For a short time until this stop, the planet gears 12a, 1
Since 2b continues to rotate, the part 2b that has been stopped until now rotates in the opposite direction and stops at the initial position. That is, the ring gear turtle 4a rotates by the amount of swing of the torsion bar 9 applied when the input shaft 3 rotates, and the spool 16 also returns to the neutral position accordingly. It operates in this way, but after the input is transmitted to the input shaft 3, this input is transmitted to the control valve turtle 7.
In fact, six gears 1 are required to move the spool 16.
1a-12a-14a, 11a-Kan 2a-12b-Turtle
b (i4b).

Therefore, even if the precision of the individual spur gears is improved, the play will be at least six times that of the individual gears. This may increase the rotation angle of the torsion bar 9 for applying reaction force, giving a sense of discomfort to the driver.In particular, even if initial accuracy is improved and play is prevented to some extent, wear due to long-term use may increase. There are also problems, and improving gear accuracy cannot be expected to have a great effect even though it will dramatically increase production costs.The present invention was proposed to solve this problem, and gear accuracy itself is not a problem. To provide a power steering device which eliminates backlash in a gear group without causing problems.

Although the main part of the present invention is shown in FIG. 3, the other configurations are the same as those shown in FIGS. 1 and 2 described above, so the explanation will be omitted. 2 Input shafts on the input side, 21 are screw shafts, and sun gears 22a and 22b, respectively.
are engraved on the circumferential surface, and planet gears 23a, 2
Ring gears 24a and 24b mesh with each other via 3b.

Here, the sun gears 22a, 22b and the ring gear 24a,
The gears 24b are each formed into a tapered gear having tapered surfaces with opposite slopes from the outside to the inside, and the disc 25 is sandwiched in the annular gear space of these back-to-back outward-facing gears. Planet gears 23a and 23b are mounted and supported on this, and these planet gears 23a and 23b are formed of relatively thin straight gears, and are inserted and supported so as to be freely rotatable on a pin 26 provided in a shield on the disk 25. , and a spring 2 whose one end supports the snap rings 27a and 27b that are engaged with the ends of the pin 26.
8a and 28M are elastically pressed.

As a result, the net gears 23a and 23b are always connected to the tapered sun gears 22a and 22b and the tapered ring gears 24a and 24a.
4b, the elastic force of the springs 28a, 28b absorbs the looseness and meshes tightly, and as a result, the positioning calendar is maintained with almost no interference between the gears, and the reaction force of the springs 28a, 28b is They cancel each other out with respect to pin 26. Furthermore, since the net gears 23a, 23b are thin, the contact area with the taper sun gears 22a, 22b and the tapered ring gears 24a, 24b is small, and therefore the frictional force during rotation is small, which also has the advantage of smooth transmission of rotation. In addition, these differential gear mechanisms C have a control valve IT
Since it is a so-called input signal transmission mechanism for cutting and cutting, no large power is transmitted, so it is also possible to use a friction wheel system instead of gears, as shown in Figure 4. . In other words, the taper sanghya 22a
, 22b, planet gears 23a, 23b, and tapered friction wheels 22'a, 22'b in which tooth portions corresponding to tapered ring gears 24a, 24b are replaced with high friction transmission parts such as knurling, serrations, particle adhesion processing, etc. ,2
3'a, 23'b and 24'a, 24'b are provided, and in this case, planet friction wheels 23'a, 23'b are also tapered and pressed into contact with disc springs 28'a, 28'b. let

This also makes it possible to eliminate play between the friction wheels and achieve accurate input transmission.

Although not shown, it is of course possible to reverse the taper direction and the position of the spring to prevent backlash.

In addition to the snap ring, means such as caulking, screwing, etc. may be used as a means for fixing the spring. In summary, the present invention consists of a differential gear mechanism for control valve switching control consisting of two rows of tapered gear type planetary gear trains, and each planet gear is pressed into contact with the taper ring gear and the taper sun gear by the elastic force of the spring. Even without significantly improving the accuracy of the gear group, rattling can be reliably prevented with an extremely inexpensive method, and the pressing force can be offset against the planet gear shaft to maintain the fixed position, and it also prevents wear. Since the planet gear is pushed forward according to the amount of wear, it is possible to always maintain a good contact state and compensate for changes in performance over time.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view of a power steering device that is the basis of the present invention, FIG. 2 is a sectional view taken along line 1-1, and FIGS. 3 and 4 show essential parts of different embodiments of the present invention. FIG. 20...Input shaft, 21...Screw shaft, 22a. 22b...7-passan gear, 23a, 2
3b... Planet gear, 24a, 24b... Narrowing gear, 25... Disc, 26... Pin, 27a,
27b""" Snap ring, 28a, 28b...Spring. Fig. 1 Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] 1. A screw shaft that is screwed into the piston of a power cylinder and an input shaft that is an input shaft are connected through a torsion bar, and the input shaft and screw shaft are tapered with opposite slopes on their respective outer peripheries. A sun gear is formed, and a planet gear is installed and supported by sandwiching a disk which is meshed with these gears and connected to each other and is rotatably arranged around the input shaft, and a ring gear with tapered slopes opposite to each other is provided on the outside of the planet gear. A differential for valve feedback control consists of two rows of tapered gear-type planetary gear trains connected by torsion bars, with one tapered ring gear fixed to the shaft and the other rotatably arranged. A gear mechanism is configured, and the movable taper ring gear is interlocked with a control valve, and as the control valve is switched by rotational displacement of the input shaft, pressure is applied to a working chamber partitioned on both sides of the piston of the power cylinder. While enabling fluid to be selectively supplied, an elastic member is provided to press each planet gear against each tapering gear and sun gear, and the pressing reaction force of the elastic member is canceled out with respect to the planet gear axis. A power steering device characterized by having a symmetrical configuration.