JPH02310176A - Power steering device for running wheel - Google Patents

Abstract

PURPOSE:To provide a steering reactive force corresponding to the car speed by furnishing an oil-hydraulic pump driven by the axle, and supplying the oil pressure in this hydraulic pump to reaction chambers which accommodate a centering spring of a control valve. CONSTITUTION:In a steering gear box 3 having a control valve 1 and an oil- hydraulic cylinder 2, a plurality of circular hole shaped reaction chambers 7 penetrating in parallel with the axis are arranged circumferentially at a sleeve 6 of this control valve 1, and two types of centering springs 15A, 15B are accommodated alternately in the circumferential direction in these reaction chambers 7. A plunger 16 is arranged on both sides of a short No. 1 spring 15A, while the two sides of No. 2 spring 15B are put in contact with centering plates 17A, 17B arranged at the two ends of a spool 5. A hydraulic pump 19 driven by the axle 20 is furnished, and the oil pressure therefrom is led to the reaction chambers 7 accommodating the No. 1 spring 15A through an oil path 21.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a power steering device for a traveling vehicle such as a tractor or construction machine.

(Prior Art) Usually, a power steering device includes a worm shaft 4 rotated by a handle 38 in a steering gear box 3 formed by a hydraulic cylinder 2 and a control valve 1, as shown in FIG. The pole nut 10 is screwed to the worm shaft 4 through the steel ball in the hydraulic cylinder 2, and the pole nut IO is meshed with the sector gear 13 attached to the sector shaft 12, and a left oil chamber 11L and a left oil chamber 11L are provided on both sides of the pole nut 10. A right oil chamber 11R is formed, and in the control valve 1, a sleeve is fitted to a spool attached to the worm shaft 4, and a pump port P, tank bow 1-T, and left and right steering boats SL and SR are formed in the sleeve. The pressure oil from the hydraulic pump 9 is transferred from the pump port P to the left and right steering boat SL by movement of the sleeve in the axial direction caused by the rotation of the worm shaft 4.
The oil pressure is supplied to one of the left and right oil chambers 11L and IIR through one of the SR and is configured to apply hydraulic pressure to the pole nut 10.

The hydraulic pump 9 is driven by the engine 8, and when the engine 8 rotates at high speed, the amount of oil discharged increases, and the hydraulic pressure applied to the pole nut 10 increases, increasing the power (steering torque) of the power steering device. There is a characteristic that

(Problem to be solved by the invention) For this reason, when special vehicles such as tractors are driven on the road at high speed, the steering wheel operation becomes too light, causing the operator to make careless steering operations or feel uneasy. Sometimes I hug you.

Therefore, as shown in FIG. 2 (first comparative example), a manual or electromagnetic type switching valve 39 is provided in the discharge oil passage 26 between the hydraulic pump 9 and the control valve 1 to avoid human interference during high-speed driving. It is conceivable to automatically detect the vehicle speed and not automatically supply power to the power steering device.

However, with this method, the power becomes zero when the switching valve 39 is activated, so the force required to operate the steering wheel changes rapidly, and the steering interval deteriorates, which is not preferable.

A second comparative example shown in FIG. 3 is an improvement on this, in which a branch oil passage 40 is connected to the discharge oil passage 26 from the engine-driven hydraulic pump 9 to the control valve 1, and this branch oil passage 40 is controlled. The centering spring 15 of the valve] is communicated with the reaction chamber 7 in which the centering spring 15 is housed, and
It is conceivable to provide a manual or electromagnetic switching valve 41 and configure the switching valve 41 to be operated by the main shift lever 42.

In this second comparative example, the main shift lever 42 is set to the low speed first shift lever.
During 2nd gear and hacking, no. .When switching to 4th speed, sensor 43A,
43B operates to operate the switching valve 41 to the communication side 1, branching the pressure oil of the hydraulic pump 9 and supplying it to the reaction chamber 7, and applying pressure to assist the elastic force of the centering spring 15 to the centering play 1 and 17A. , 17B, and force the steering wheel operation.

In the second comparative example, as the engine speed increases, such as when traveling at high speed on a road or road, the oil pressure in the reaction chamber 7 also increases, and the steering wheel operation, which is attempted to be made lighter by increasing the amount of pressure oil from the hydraulic pump 9, This means that the main shift lever 42 is controlled by a larger force, and there is some vehicle speed response, but the steering force changes greatly depending on the operation of the switching valve, and the main shift lever 42 is
Even when driving at a low speed (such as when starting off on the road), hydraulic pressure is added to the reaction chamber 7, so the steering wheel in that state becomes heavier than necessary, resulting in poor handling. It's hard to say it will be the best.

The present invention can solve the problems of the various techniques described above by providing a hydraulic pump driven by an axle and supplying oil discharged from the hydraulic pump according to the vehicle speed to the reaction chamber. An object of the present invention is to provide a power steering device for a traveling vehicle.

(Means for Solving the Problems) A specific configuration for solving the problems in the present invention is a power steering system for a traveling vehicle that is operated by pressure oil supplied from a hydraulic pump 9 driven by a traveling drive engine 8. , a hydraulic pump 19 driven by an axle 20 is provided, and pressure oil from the hydraulic pump 19 can be supplied to the reaction chamber 7 in which the centering spring 15 of the control valve I is housed.

(Function) When the vehicle speed increases and the rotational speed of the hydraulic pump 19 driven by the axle 20 increases, the hydraulic pressure applied to the reaction chamber 7 also increases, and the centering play 1174. +7[The force (recoil force) to project 1 increases. Therefore, the reduction in steering wheel operation due to an increase in the amount of oil discharged from the engine-driven hydraulic pump 9 is suppressed.

When the engine 8 is rotated at high speed when working in the field or traveling at two speeds, the hydraulic pressure supplied to the pump boat P of the control valve 1 increases, making the steering wheel easier to operate. However, since the vehicle speed is low, the pressure is low and the force to suppress steering wheel operation is weak.

(Example) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, a steering gear box 3 having a control valve 1 and a hydraulic cylinder 2 is similar to that of the prior art, and a sleeve 6 is fitted to a spool 5 attached to a rear l and a shaft l, 1. Peripheral grooves are formed on the mating surfaces of both, and the sleeve 6 has pump boat P, tank boat Tl, T2, left and right steering boats (SL, SR).
A plurality of circular bow-shaped reaction chambers 7 are arranged in a circular manner, and the reaction chambers 7 are formed in a circular manner and extend parallel to the axis.

The pump boat 1-P is an engine 8 for driving a traveling vehicle.
The hydraulic pump 9 driven by the tank boat T1. T2 is connected to a power steering tank or a tank substituted by a minsion case, one of the left and right steering boats SL and SR is connected to the oil chamber 11R to apply hydraulic pressure to one side of the ball nand 10, and the other is connected to the oil chamber 11R for applying hydraulic pressure to one side of the ball nand 10. It is connected to an oil chamber 11L in which a sector shaft 12 and a sector gear 13 are located so as to apply hydraulic pressure to the other surface of the sector 10.

In the example, IIL is the oil chamber for the left steering boat,
If you rotate the worm shaft 4 clockwise, the spool 5 will move to the first position.
0 Move to the right, pump boat P and left steering boat S
L is communicated with the oil chamber 11L to supply pressure oil to the oil chamber 11L.

Two types of centering springs 154.15B are housed alternately in the circumferential direction in the complementary reaction chamber 7, and the first centering spring 15A is short and has plungers I6 arranged on both sides thereof.

The first centering spring 15A is connected to each plunger 16.
At the same time, the outer end of the second centering spring 15B engages the centering plays 1-17A and 17B arranged at both ends of the spool 5, respectively.
Hydraulic cylinder 2 and shaft end cover 18 on both sides of sleeve 6
It is possible to contact with.

Reference numeral 19 denotes a hydraulic pump driven by an axle 20 such as a rear axle or a front axle of the traveling vehicle, and a trochoid pump or the like is adopted.
Recoil chamber 7 containing centering spring 1.5A
It has a constriction part 22 in the middle.

The rotation of this hydraulic pump 19 increases in proportion to the vehicle speed, generates a pressure corresponding to the vehicle speed from low pressure to high pressure, and applies a pressing force to the plunger 16 in addition to the elastic force by the first centering spring 15A. Therefore, centering plate 1
A movement resistance is applied to the spool 5 through the worm shaft 7, thereby increasing the movement reaction force against the worm shaft 4.

Note that the oil passage 21 may be connected to the reaction chamber 7 housing the second centering spring 15B, or may be connected to the entire reaction chamber 7,
A and 15B may be of a smaller elastic force than those of the prior art, or the diaphragm portion 22 may be of a variable diaphragm type.

4 to 6 show an example of a handling adjustment device that automatically adjusts the amount of oil discharged from the power steering hydraulic pump 9 to prevent the steering wheel from becoming too light even when the engine rotates at high speed.

An orifice 27 is formed in the discharge oil passage 26 of the hydraulic pump 9, and a flow rate regulating valve 28 is provided downstream of the orifice 27. In this flow rate regulating valve 28, a spool body 30 is slidably disposed within a valve body 29, and one end of the valve body 29 is connected to the orifice 27.
It is connected to the high pressure side in the northern part of the state via an oil line 31, and the other end is connected to the downstream low pressure side via an oil line 32.

A spring 33 is disposed at the other end of the valve body 29 to urge the spool body 30 toward one end, and when the pressure difference in the oil passage 3L32 is relatively small, the spool body 30 is approximately located at the position shown in FIG. When the pressure difference becomes large, the spool body 30 is pushed in a direction that compresses the spring 33, as shown in FIG.

The spool body 30 is formed with a passage 30a having a smaller cross-sectional area than the discharge oil passage 26, and a drain 30b that communicates with the discharge oil passage 26 when pushed in the spring compression direction. 29 and the circumferential upper side suction oil passage 34 of the hydraulic pump 9 are always in communication with a bypass oil passage 35 .

Therefore, as the engine speed increases from zero, until the engine speed reaches a certain level, as shown in Fig. 6, the protruding oil passage 2
6 increases proportionally, the power of the power steering device increases, and as soon as the engine speed reaches a constant speed, the pressure difference between the oil passages 31 and 32 increases,
When the drain 30b of the spool body 30 pushed in the spring compression direction communicates with the protruding oil passage 26, the discharged oil escapes to the inlet side of the hydraulic pump 9 through the bypass oil passage 35.
The flow rate on the downstream side of the spool body 30 does not increase, and even if the engine speed becomes higher still, the opening area of the exhaust cable 30h increases, so the flow rate remains approximately constant.

As a result, even when driving at high speeds on the road, the power of the power steering device does not become too large and the steering operation becomes too light, and the steering interval can be improved. It is possible to act as a power amplifier for the power steering device during rotation, and even if this is done, the characteristics of the power steering device will not be adversely affected.

(Effects of the Invention) According to the present invention described in detail above, the rotation of the hydraulic pump 19 increases in proportion to the traveling speed of the vehicle, and the hydraulic pressure supplied to the reaction chamber 7 increases, so when the vehicle is traveling on the road, etc. When the engine 8 rotates at high speed and the vehicle speed increases, hydraulic pressure corresponding to the vehicle speed can be added to the elastic force of the centering spring 15, which prevents steering wheel operation from becoming too light during high-speed driving. It can enable sensory steering. Further, when the engine rotates at high speed and the vehicle runs at low speed, the rotation of the hydraulic pump 19 is low and the hydraulic pressure applied to the reaction chamber 7 is low, so that the steering wheel operation does not become heavy.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an embodiment of the present invention, Fig. 2 is a sectional view showing a first comparative example, Fig. 3 is an explanatory opening showing a second comparative example with number J, and Figs. 4 to 6 are a handling adjustment device. FIG. 4 is an explanatory diagram when no adjustment is made, FIG. 5 is an explanatory diagram when adjustment is made, and FIG. 6 is a graph showing the relationship between the engine speed and the amount of supplied oil. 1... Control valve, 2... Hydraulic cylinder,
5... Spool, 6... Sleeve, 7... Recoil chamber, 9... Hydraulic pump, 15... Centering spring, 17... Centering plate, 19... Hydraulic pump, 20... Axle , P... pump boat, T...
・Tank boat 1・, S... Steering boat. 】2 Tomizuka \ Pede 2] 1. Display of the case Patent Application No. 133318 of 1999 2. Name of the invention Power steering device for a traveling vehicle 3. Person making the amendment Relationship to the case Patent application Name of person (105) Kubota Iron Works Co., Ltd. 4th generation
Rito 1013 Mikuriya, Higashiosaka City, Osaka Prefecture Telephone: 06 (782) 6917/6918 Heisei
Year, month, day (voluntary) 6. Subject of amendment/Detailed explanation of the invention in the specification/Brief explanation of drawings in the specification/Drawing 7, Contents of amendment 7, Contents of amendment (]) Details The claims of the book are amended as shown in the attached sheet. (2) In the 1st and 2nd lines of the third page, the text "(steering torque)" is corrected to "(output, steering force)". (3) Page 4, lines 2-3, lines 7, 13 and 17, page 5, line 4.20, page 6, line 4.13, page 8, line 16
line and page 11, lines 16-17, and page 12, line 4, “
``Reaction chamber 7'' is corrected to ``Reaction chamber 7AJ.'' (4) Page 5, line 20, page 6, lines 5-6, and 11.
In the 20th line of the page, "Spring 15" is corrected to "Spring 15A". (5) On page 6, line 13 of the same page, the phrase “left ga” is replaced with “pressure ga”.
and correct it. (6) In the second line of page 8 of the same page, it says "There are two types of reaction chambers" and "there are reaction chambers 7B and 7B alternately in the circumferential direction." and correct it. (7) On page 9, lines 5 to 7, “In addition,...
” should be corrected to ``In addition,''. (8) Figure 1.3 of the attached drawings is corrected as shown in the attached sheet (codes 7A and 7B are corrected). 2. Claims (1) In a power steering device for a traveling vehicle that is operated by pressure oil supplied from a hydraulic pump (9) driven by a steering drive engine (8), the power steering device is driven by an axle (20). A hydraulic pump (]9) is provided, and pressure oil from the hydraulic pump (19) can be supplied to a reaction chamber (7A) containing a centering spring (15A) of the control valve (1). Power steering device for moving vehicles.

Claims (1)

[Claims] (1) In a power steering device for a traveling vehicle that is operated by pressure oil supplied from a hydraulic pump (9) driven by a traveling drive engine (8), a hydraulic pump (19) driven by an axle (20) is used. A power steering device for a traveling vehicle, characterized in that the pressure oil from the hydraulic pump (19) can be supplied to a reaction chamber (7) containing a centering spring (15) of a control valve (1).