JPS616073A - Power steering device for car with variable-capacity type pump - Google Patents

Abstract

PURPOSE:To reduce the power loss while adequately keeping the steering feeling of a power steering device by driving a motor pump at the optimum overall efficiency. CONSTITUTION:Th motor pump PM of a power steering device is provided with a rotary motor M coaxially assembled in a tank housing 40, a filter 50, and a variable-capacity type oil pump P. The optimum pressure fluid feed quantity for a means aiding the action of a steering mechanism is determined based on the running speed of a car as the first output signal. The optimum rotating speed of the rotary motor is determined based on the value of the first output signal as the second output signal, which is applied to the rotary motor. The optimum variable capacity of the pump is determined based on the value of the first output signal as the third output signal, which is applied to a capacity control means.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power steering device for a vehicle, and more particularly to a power steering device for a vehicle equipped with a variable displacement electric pump.

[Prior art]

Conventionally, in this type of power steering device, there is one in which a variable displacement electric pump serving as a power source is constituted by, for example, a rotary electric motor and a variable displacement oil pump driven by the rotary electric motor.

However, in such a configuration, although the power loss of this type of power steering device is reduced by variable displacement control of the oil pump and rotation speed control of the rotary electric motor, the oil pump as an electric pump and the rotary electric motor are The oil pump and rotary electric motor are not driven in such a way that the overall efficiency is as high as possible, and this has been an obstacle to reducing power loss in this type of power steering system.

[Purpose of the invention]

The present invention was made in response to such problems,
The purpose of this invention is to maintain a high overall efficiency of the electric pump in a vehicle power steering system equipped with a variable displacement electric pump.

[Structure of the invention]

In achieving this objective, the structural features of the present invention are as follows:
A steering mechanism that operates in response to the rotation of the vehicle's steering shaft to steer the steering wheels, and a variable displacement pump that generates pressurized fluid in accordance with the rotational speed of the rotary electric motor with an amount corresponding to the variable displacement. an electric pump, an assisting means for assisting the operation of the steering mechanism by being supplied with pressure fluid from the pump in response to rotation of the steering shaft, and a capacity control means for controlling a variable displacement of the pump. In the steering device, a first detection means detects the traveling speed of the vehicle and generates this as a first detection signal, and a second detection means detects the rotational speed of the rotary electric motor and generates this as a second detection signal. , a third detection means for detecting the variable displacement of the pump and generating it as a third detection signal; and a third detection means for detecting the variable displacement of the pump and generating the third detection signal;
The optimum pressure fluid supply amount is determined according to the value of the detection signal.
a first output signal generating means for generating an output signal, and a predetermined relationship between the optimum pressure fluid supply amount and the optimum rotational speed of the rotary electric motor under the optimum overall efficiency of the rotary electric motor and the pump; a second output signal generating means for determining the optimum rotational speed according to the value of the first output signal and generating it as a second output signal and applying it to the rotary electric motor; and the optimum pressure fluid supply amount under the optimum overall efficiency. and generating a third output signal that determines the optimum variable capacity according to the value of the first output signal from a predetermined relationship between The reason is that the means have been established.

〔Effect of the invention〕

By configuring the present invention in this way, the value of the first output signal (i.e., the optimum pressure fluid supply amount) is -
The value of the second output signal (i.e., the optimal rotational speed) is determined according to the value of the first detection signal from a predetermined relationship between the traveling speed of the vehicle and the optimal amount of pressure fluid supplied to the assisting means. determined according to the value of the first output signal from a predetermined relationship between the optimum pressure fluid supply amount and the optimum rotational speed of the rotary electric motor under the optimum overall efficiency of the rotary electric motor and the pump; The value of the third output signal (i.e., the optimal variable displacement) is determined from the predetermined relationship between the optimal pressure fluid supply and the optimal variable displacement of the pump under the optimal overall efficiency. is calculated according to the value,
The rotary electric motor is driven based on the value of the second output signal, and the pump is driven by the rotary electric motor with a variable capacity based on the value of the third output signal. The electric pump is always driven at its optimum overall efficiency while optimally maintaining the amount of pressure fluid necessary for the assisting action of the assisting means to operate the steering mechanism, and as a result, this type of power steering device The power loss of the co-powered steering device can be further reduced while maintaining a positive steering feel.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.
3 to 3 show the overall configuration of a power steering device for a vehicle according to the present invention. As shown in FIG. 2, this power steering device includes a steering mechanism 10.
In response to the leftward (or rightward) rotation of the steering shaft 12 in conjunction with the leftward (or rightward) rotation of the steering handle 11, the piston 21 of the power cylinder 20 is moved to the right within this power cylinder 20. (or to the left) and steer the wheel 1.
3 to the left (or right).

The power steering device also includes a servo valve 30 coaxially assembled to the steering shaft 12, a variable displacement electric pump PM, and an electric control circuit EC connected to the electric pump PM. By rotating the steering shaft 12 to the left, each pipe Pi, P5 is connected to each pipe P4 . P3 respectively, and the pressure oil applied from the electric pump PM through the pipe P1 as described later is throttled to an amount corresponding to the leftward rotation of the steering shaft 12 through the pipe P4 to the left side of the power cylinder 20. The remaining pressure oil is passed through the pipe P5 to the electric horn 7'.
At the same time, the pressure oil in the right chamber 23 of the power cylinder 20 is circulated through the pipe P3 and into the electric pump PM through the pipe P5.

Furthermore, the servo valve 30 connects each pipe PI, P5 to each pipe P3, . P4, and the pressure oil applied from the electric pump PM through the conduit P1 is throttled to an amount corresponding to the rightward rotation of the steering shaft 12 through the conduit P3 and into the right chamber 23 of the power cylinder 20. The remaining pressure oil is returned to the electric pump PM through the pipe P5, and the pressure oil in the left chamber 22 of the power cylinder 20 is returned to the electric pump PM through the pipe P4, and the remaining pressure oil is returned to the electric pump PM through the pipe P5. let This means that the power cylinder 20 moves the piston 21 to the right (or left) under the hydraulic pressure generated in the left chamber 22 (or right chamber 23) in cooperation with the servo valve 30.
to the left (or right) of the steering handle 11.
It means to assist in the rotation operation. Note that when the steering handle 11, that is, the steering shaft 12 is in a neutral state, the servo valve 30 operates to control each of the pipes PI, P3. P4 is communicated with conduit P5.

As shown in FIG. 3, the electric pump PM includes a tank housing 40, a DC motor M coaxially assembled within the tank housing 40, a filter 50, and a variable displacement oil pump P.

The DC motor M includes a motor housing 60 and an armature 70 coaxially assembled within the motor housing 60. The motor housing 60 has a cylindrical yoke 61 and a pair of O-rings 61a at both ends.

Both end brackets 62 and 63 are fitted through 61b. The end bracket 62 has a stepped portion 62
Attach the O-ring 4 to the opening 41 of the tank housing 40 at point a.
1a, and this end bracket 62
An inlet 62b and an annular groove 6 for communicating the pipe P5 into the tank housing 40 via the filter 50 are provided on the outer periphery of the pipe P5.
2C (see Figure 4) is drilled. Note that in FIG. 3, reference numeral 62d indicates an input terminal.

The armature 70 is rotatably supported at one end 71 of its rotating shaft by a bearing portion 62e of an end bracket 62 via a sleeve metal 71a, and a spline shaft portion formed at the other end of the rotating shaft of the armature 70. 72 is inserted into the spline hole 1 of the pump cylinder 110 of the oil pump P by passing the oil seal 63a fitted into the shaft hole of the end bracket 63.
The pump cylinder 110 is rotatably fitted into the pump cylinder 110 by a spline connection. filter 50
As shown in FIG. 4, it is bent in a wave shape to form an annular shape, and is fitted coaxially around the outer periphery of the motor housing 60 of the DC motor M. Therefore, this filter 50 is connected to the annular groove 62C of the end bracket 62 and the reservoir part 42 (
This removes impurities in the hydraulic oil flowing back between the motor housing 60 and the tank housing 40 (which is a substantially annular hollow part formed between the motor housing 60 and the tank housing 40 and stores the hydraulic oil). In addition, the third
In the figure, reference numeral 73 indicates a brush, which is supported by one end of the yoke 61 and receives a current supplied from the input terminal 62d to the commutator 74 of the armature 70, and supplies the current to the commutator 74. Further, reference numeral 61c indicates a magnetic pole (consisting of a permanent magnet) of the yoke 61, and reference numeral 43 indicates the tank housing 40.
It shows a camp that removably seals the supply port 40a of the
Further, reference numeral 44 indicates an oil level gauge that measures the amount of hydraulic oil in the reservoir section 42.

As shown in FIG. 3, the oil pump P includes a pump housing 80 and a cylindrical valve 90 assembled into the pump housing 80. Cam ring 100 and pump cylinder 11
0, the pump housing 80 is integrally formed coaxially with the end bracket 63 of the motor housing 60, and has an O-ring 81 at its central flange portion 81.
It is fitted into the open end 45 of the tank housing 40 via the hole a. The pump housing 80 includes a stepped inner hole 82 bored coaxially with the armature 70 and an inlet 83 , 83 . 83 (see Figure 5) and stepped inner hole 82
It has an outflow passage 84 (see FIGS. 3 and 8) bored so as to communicate the small diameter part 82a of the stepped inner hole 82 with the pipe P1, and a valve 90 is provided in the small diameter part 82a of the stepped inner hole 82. is fitted by press fitting.

As shown in FIGS. 3, 5, and 6, the valve 90 has two annular grooves 91 and 92 formed in parallel on its outer peripheral surface, and the annular groove 91 is connected to the inlet of the pump housing 80. 83, 83.83, while the annular groove 92 is located opposite the outflow passage 84. Further, the valve 90 is
As shown in FIG. 3, FIG. 5, FIG. 6, and FIG. As shown in FIG. 5, a hole is bored along the bottom wall of the annular groove 91 at a half portion on the upper side as shown in FIG. As shown in FIGS. 3 and 6, the notch 92a is bored along one side of the bottom wall of the annular #92 in the lower half (not shown) of the annular groove 92 of the valve 90. It communicates with the inside of the hollow part. As shown in FIGS. 3 and 7, the balance groove 92b is formed along the other side of the bottom wall of the annular groove 92 and opens into the hollow part of the valve 90 at the upper half shown in FIG. The balance groove 92b communicates from a part of the bottom wall with the annular ti92 through a communication hole 92C at the center of the bottom wall.

The cam ring 100 is made of a ball bearing, and as shown in FIGS. 3 and 8, the cam ring 100 is fitted into the large diameter portion 82b of the stepped inner hole 82 so as to be eccentric in the left-right direction as shown in FIG. There is. As shown in FIG. 3, the pump cylinder 110 has a disk portion 110a and a disk portion 110b extending coaxially from the center of the disk portion 110a.
The disk portion 110b is rotatably fitted within the valve 90, and the disk portion 110a is disposed within the hollow portion of the cam ring 100. In such a case, the outer diameter of the disc portion 110a is adjusted by a predetermined length corresponding to the eccentricity em at the position shown in FIG. 8 of the cam ring 100, that is, the maximum eccentricity em.
It is shorter than the inner diameter of 0. However, pump cylinder 1
10 is eccentric from the central axis of the large diameter portion 82b of the stepped inner hole 82 by the predetermined length (see FIG. 8).

As shown in FIGS. 3 and 8, the disc portion 110a of the pump cylinder 110 has seven cylinder holes 112 to 112 drilled radially.
12, each piston 113-113 is slidably fitted through each coil spring 114 assembled into each assembly hole 113a to form a pump chamber. Further, each of the pistons 113 to 113 is brought into contact with the inner circumferential surface of the cam ring 100 under the elastic action of each coil spring 114 at its respective hemispherical head 113b.

The pump cylinder 110 has seven communicating passages 115 to 11.
5 are bored at equal intervals in the circumferential direction from the outer peripheral part of the columnar part 110b to the center of the disc part 110a, and each of these communication passages 115 connects each cylinder hole 112 through a communication port formed at the bottom of each of the communication passages 115. It communicates with the pump chamber. Also,
The columnar portion 110b has seven communication holes 116 to 116 and 117 to 117 in the radial direction corresponding to each communication path 115 to 115, respectively, as shown in FIGS. 3, 5, and 7. Each communication hole 116 to 116 is
The notch 91a of the valve 90 is selectively communicated with each communication path 115-115, and each communication hole 117-117 selectively communicates each communication path 115-115 with the notch 92,1 of the valve 90. In FIG. 3, reference numeral 85 indicates an end plate fitted into the opening of the pump housing 80 via an O-ring 85a.

A pair of bosses 86 and 87 are provided on the peripheral wall portion of the pump housing 80 that extends outward from the tank housing 40.
As shown in the figure, these bosses 86 and 87 are opposed to each other and protrude in opposite directions through the cam ring 100.
Control piston mechanisms 120 and 130 are respectively assembled in the through holes. The control piston mechanism 120 includes a guide member 121, a control piston 122, and a coil spring 123. The guide member 121 has a cross-shaped hollow part (see FIG. 9) and a stepped inner hole. 82
The boss 87 is press-fitted into the opening of the boss 87 into the large diameter portion 82b.

The control piston 122 is connected to the guide member 121 and the male tap 1.
23 (attached to the threaded portion of the outer end of the through hole of the boss 87 via an O-ring 124a). A roller 122c is rotatably supported by a shaft 122b between both arm portions 122a, 122a (see FIG. 9) that extend movably in the axial direction of the control piston 122 within the guide member 121. When bending, both arms 122
a, 122a and roller 122c are the guide member 121
Because of the cross shape of the hollow part, it is impossible to rotate around the axis of the boss 87. The coil spring 123 is connected to the boss 87
The control piston 122 is assembled in an oil chamber 87a between the control piston 122 and the male tap 124 in the cam ring 10, and constantly urges the control piston 122 toward a part of the outer peripheral surface of the cam ring 1°O. This means that the roller 122c is pressed against a part of the outer circumferential surface of the cam ring 100 so as to be able to roll and come into contact with it.

The control piston mechanism 130 includes a guide member 131 (having the same configuration as the guide member 121) and a control cylinder 1.
32 and a control piston 133 (having a smaller pressure-receiving area than the control piston 122), the guide member 131 has a boss 8 into the large diameter portion 82b of the stepped inner hole 82.
It is fitted into the opening of 6 by press fitting. The control cylinder 132 is press-fitted into the through hole of the boss 86 behind the guide member 131, and a control piston 133 is fitted in the control cylinder 132 so as to be slidable in the axial direction. . Control piston 132 to guide member 1
A roller 132C is rotatably mounted on a shaft 132b between both arms 132a, 132a (only one of which is shown in FIG. 8) extending physically. supported.

In such a case, both arm portions 132a, 132a and roller 13
2c is a cross-shaped hollow part of the guide member 131;
It is not possible to rotate around the axis of the boss 86.

Inside the boss 85, the control cylinder 132 and the male threaded plug 13
4 (attached to the female threaded portion of the outer end of the N through hole of the boss 86 via the O ring 134a).

The oil chamber 86a thus formed communicates with the outflow passage 84 through a branch passage 86b. This means that the control piston 133 slides to the right in FIG.
c is pressed against the outer circumferential surface of the cam ring 100 so that it can roll and come into contact with the cam ring 100. Note that the outflow passage 84 is formed from the stepped portion of the pump housing 80 to the peripheral wall portion of the boss 86 . Further, in FIG. 8, reference numeral 86c indicates an outlet formed in the boss 86, and this outlet 86C connects the outlet passage 84 to the oil passage P1.

Further, as shown in FIG. 10, a pair of outflow passages 87b and 87c connected in series are bored from the peripheral wall step of the pump housing 80 to the boss 87.
b communicates with the annular groove 92 of the valve 90 at its upstream side, while the outflow path 87c communicates into the reservoir section 42 at its downstream side. A fixed orifice 88 is interposed in the outflow passage 87b, and its predetermined constriction area throttles the amount of pressure oil from the annular groove 92 (functions). The downstream side of the fixed orifice 88 in the outflow path 87b is communicated with the inside of the oil chamber 87a.

The electromagnetic proportional variable throttle valve 140 includes a linear actuator 141 assembled to a part of the outer wall of the boss 87 and an outlet passage 87.
The linear actuator 141 directs the needle-shaped valve body 142a of the variable throttle valve 142 toward the valve seat 142b by a displacement amount proportional to the current flowing into the solenoid. Displace.

This means that the opening degree of the variable throttle valve 142 is proportional to the input current to the solenoid of the three-way actuator 141. However, when the current flowing into the solenoid is zero, the opening degrees of the variable throttle valves 1 and 42 are at the maximum (that is, corresponding to the throttle degree of zero).

As shown in FIG. 1, the electric control circuit Ec includes a differential transformer 150, a vehicle speed sensor 160, and a rotational speed sensor 17.
0, and frequency-voltage converters 160a and 170a connected to the vehicle speed sensor 160 and the rotational speed sensor 170, respectively.
(hereinafter referred to as F-V converters 160a and 170a), differential transformer 150 and each F-V converter 160a and 1
Each A-D converter 150a, 1 connected to 70a, respectively.
60b and 170b. The differential transformer 150 is assembled to the outer end of the boss 87 of the pump housing 80, as shown in FIGS. The control piston 12 extends displaceably into the oil chamber 87a.
It is connected to 2. Thus, the differential transformer 150 detects the eccentricity e of the cam ring 100 as the displacement of the displacement rod 51 due to the sliding of the control piston 122, and generates this detection result as an analog displacement voltage. In this case, when the eccentricity e of the A-D converters 150a, 160b, and 170b is equal to em, the displacement of the displacement rod 151 of the differential transformer 150 takes the maximum value.

The vehicle speed sensor 160 detects the actual vehicle speed of the vehicle and generates a series of vehicle speed pulses at a frequency proportional to this detection result.The zero rotation speed sensor 170 detects the actual rotation speed of the DC motor M (i.e., the pump cylinder 110). is detected and generates a series of rotational speed pulses at a frequency proportional to this detection result. The F-V converter 160a converts the frequency of each vehicle speed pulse from the vehicle speed sensor +160 into a proportional analog vehicle speed voltage, while the F-V converter 170a converts the frequency of each rotational speed pulse from the rotational speed sensor 170. This is converted into an analog rotation speed voltage proportional to this. The A-D converter 150a digitally converts the analog displacement voltage from the differential transformer 150 and generates a digital displacement voltage Vt.
A-to-D converter 170 converts the analog vehicle speed voltage from a into digital to generate a digital vehicle speed voltage Vs.
b generates the analog rotational speed voltage from the F-V converter 170a as a digital rotational speed voltage Vn.

The electric control circuit Ec also includes a function generator 180 connected to the A-D converter 160b, a function generator 190 connected to the A-D converter 150a and the function generator 180, and a function generator 190 connected to the A-D converter 150a and the function generator 180.
A function generator 200 connected to the D converter 170b and the function generator 180, each D-A converter 190a, 200a connected to each function generator 190, 200, and the D-
Voltage-current converter 190b connected to A converter 190a
(hereinafter referred to as the V-1 converter 190b), a power amplifier 190C connected between the linear actuator 141 and the V-1 converter 90b, and a power amplifier connected between the I)-A converter 200a and the DC motor M. 200b.

The function generator 180 generates predetermined characteristic data that defines the relationship between the digital pressure oil amount voltage q representing the optimal discharge pressure oil amount q from the oil pump P and the vehicle speed voltage Vs representing the actual vehicle speed of the vehicle. 1) qs (see FIG. 11) is stored in advance, and this function generator 180 generates a digital pressure oil amount voltage according to the digital vehicle speed voltage Vs from the A-D converter 160b based on the characteristic data Dqs. It is generated to find Vq. The function generator 190 generates a digital pressure oil amount voltage Vq, a digital opening voltage 0 representing the optimum opening of the electromagnetic proportional variable throttle valve 140, and a digital displacement representing the displacement of the displacement rod 151 of the differential transformer 150. The function generator 190 stores in advance a predetermined map Ma (see FIG. 12) that defines the relationship between the quantity voltage Vt and the A-D converter 15.
Digital displacement voltage Vt from 0a and function generator 1
A digital opening voltage Vo is determined and generated according to the digital pressure oil amount voltage Vq from 80.

The function generator 200 generates a digital drive voltage M necessary for driving the DC motor M at an optimum rotation speed, a digital pressure oil amount voltage Vq, and a digital rotation speed voltage V representing the actual rotation speed of the DC motor M. A predetermined map Mb (see FIG. 13) that defines the relationship between A digital drive voltage VM is determined and generated according to the speed voltage Vn and the digital pressure oil amount voltage vq from the function generator 180. In this embodiment, each of the above maps Ma, M
b is a characteristic curve representing the relationship between efficiency/maximum efficiency and actual rotational speed in DC motor M (see Fig. 14)
and a characteristic curve (first
(See Figure 5), it is determined that the overall efficiency of the electric pump PM is always maintained at its highest. In addition, Map Ma
, the digicle opening voltage Vo=Voi corresponds to the fully closed state of the variable throttle valve 140.

The DA converter 190a converts the digital opening voltage Vo from the function generator 190 into an analog opening voltage. D-
The A converter 200a converts the digital drive voltage VM from the function generator 200 into an analog drive voltage. The V-1 converter 190b converts the analog opening voltage from the DA converter 190a into a drive current proportional to this. In such a case, the driving current of the V-■ converter 190b is inversely proportional to the opening degree of the variable throttle valve 142. The power amplifier 190C is V-
The drive current from the converter 190b is amplified as an amplified drive current to drive the linear actuator 141 of the variable throttle valve 140.
attached to the solenoid. The power amplifier 200b is D-A
The analog drive voltage from the converter 200a is amplified as an amplified drive voltage and applied to the DC motor M.

In this embodiment configured as described above, if the device of the present invention is operated after the vehicle is running straight ahead at high speed, each of the pipes P'l, P3. P4 is opened into the reservoir part 42 of the tank housing 40 through the pipe P5, the inlet 62b of the end bracket 62 of the DC motor M, the annular groove 62C%, and the filter 50 under the action of the servo valve 30. Oil chamber 8 in boss 86 of pump housing 80
Both the oil pressure inside the boss 870 and the oil pressure in the oil chamber 87a of the boss 870 become almost zero. Therefore, the cam ring 100 is pushed toward the left in FIG. 8 by the roller 122c under the repulsive force of the coil spring 123 against the control piston 122, and is eccentrically eccentric to the position of the maximum eccentricity em.

Also, the differential transformer 150 is the cam ring 1o.

The eccentricity e"'em is detected and generated as an analog displacement voltage, and the A-D converter PA converter 150a converts the increased analog opening voltage into a digital displacement voltage Vt, and the F-V converter 160a converts it into a digital displacement voltage Vt. An analog vehicle speed voltage is generated in cooperation with the vehicle speed sensor 160, and the analog vehicle speed voltage, which is applied by the A-D converter 160b, is converted into a digital vehicle speed voltage Vs, and the F-
V converter] 70a generates an analog rotation speed voltage in cooperation with the rotation speed sensor 170, and the A-D converter 17o
A digital rotation speed voltage Vn (set to zero at this stage) is generated from the analog rotation speed voltage applied by b.

Then, the function generator 180 generates the digital pressure oil amount voltage Vq based on the characteristic data Dqs (see FIG. 11) in response to the digital vehicle speed voltage Vs from the A-D converter 16ob, and the function generator 190 generates the A-D A map Ma (see FIG. 2) is generated according to the digital displacement voltage VL from the converter 150a and the digital pressure oil amount voltage Vq from the function generator 18o.
The function generator 200 generates the digital opening voltage Vo-Vo i based on the digital rotational speed voltage Vn=Q from the A-D converter 170b and the digital pressure oil amount voltage Vq from the function ordering device 80. A digital drive voltage VM is generated based on the corresponding map Mb (see FIG. 13).

Next, the DA converter 190a converts the digital opening voltage ■0=■O1 from the function generator 190 into an analog opening voltage, and the V-1 converter 190b converts the analog opening voltage into a drive current. In response, power amplifier 1
90C generates an amplification drive current, and the D-A converter 200a
converts the digital drive voltage VM from the function generator 200 into an analog drive voltage, and in response, the power amplifier 2
00b generates the amplification drive voltage. Thus, the variable throttle valve 140 is fully closed in response to the amplified drive current from the power amplifier 190b, and the DC motor M is connected to the power amplifier 2.
The amplified drive voltage from 00b is received at the input terminal 62b to rotate the armature 70.

In this way, when the DC motor M rotates with the variable throttle valve 140 fully closed, the pump cylinder 1 of the oil pump P
10 rotates under the maximum eccentricity em of the cam ring 100 and transfers the hydraulic oil in the reservoir section 42 to the pump housing 80.
through each inlet 83 (see FIGS. 3 and 5), the annular i91 of the valve 90, and the notch 91a, and pumped up into the communication hole 116 (see FIG. 5) communicating with the notch 91a. The hydraulic oil pumped up into each communication hole 116 in this way is
Each cylinder hole 112 communicates with each of these communication paths 115 through each communication path 115 that communicates with each of these communication holes 116.
is drawn into the pump chamber according to each outward sliding movement of each piston 113 thereof. Furthermore, when the pump cylinder 110 rotates, each communication hole 116 that was communicating with the notch 92a as described above is cut off from the notch 91a, and each piston 113 that has been sliding outward as described above is moved to the cam ring. Each communication passage 115 and each communication hole 117 slide inward of each cylinder hole 112 under sliding contact with the inner circumferential surface of 100, and communicate the pressure oil in each pump chamber with each of these pump chambers. The liquid is sequentially passed through and discharged into the notch 92a (see FIG. 6) of the valve 90 that communicates with each of these communication holes 117.

The pressure oil discharged into the notch 92a in this way flows through the annular groove 92 of the valve 90. It flows into the balance groove 92b through the communication hole 92C, and also flows into the annular groove 92° pump housing 80.
outflow passage 84. Outlet 86C3 pipe Pi, servo valve 30
, inlet 62b of pipe p5.17 doburakesoto 62,
It flows into the reservoir section 42 through the annular groove 62C and the filter 50. This means that the boss 8 of the pump cylinder 80
This means that no oil pressure is generated in the oil chamber 86a at 6, and the cam ring 100 maintains the maximum eccentricity em.

In such a case, each notch 91a, 92a and balance groove 92
b is formed in the valve 90 as described with reference to FIGS. 3, 5, and 7, so that the pump cylinder 1
Both notches 91a on which the ten cylindrical portions 110b act in opposition to each other.

The armature 70 can be supported coaxially with the rotation axis of the armature 70 with high precision under balance due to the relationship between each oil pressure in the balance groove 92a and the oil pressure in the balance groove 92b. This means that the valve 90 serves as a highly accurate bearing valve for the pump cylinder 11O by employing both the notches 91a, 92a and the balance groove 92b. Further, as can be easily understood from the above, since the fully closed state of the variable throttle valve 140 and the rotational speed of the DC motor M are determined in relation to the two manipulators Ma and Mb, the high-speed straight traveling state of the vehicle As a result, the power loss of this type of power steering device when the vehicle is traveling straight at high speed can be further reduced.

At this stage, if the vehicle is brought into a medium speed running state and the steering wheel 1 is rotated to the left, the steering shaft 12 will be rotated to the left in accordance with the rotational force applied to the steering wheel 11. The piston 21 of the power cylinder 20 is moved to the right chamber 2.
3 side to steer the steering wheels 13 to the left. Further, the servo valve 30 throttles the pressure oil applied through the pipe P1 to an amount corresponding to the rotational force of the steering shaft 12 in the left direction.
4 to the left chamber 22 of the power cylinder 20, and the remaining pressure oil and the pressure oil applied from the right chamber 23 through the pipe P3 to the pipe P5, the inlet 62b of the end bracket 62, (
The power cylinder 20 enters the left and right chambers 22 through the filter 50 and the power cylinder 20.
．． The piston 21 is moved to the right in accordance with the differential pressure between the pistons 23 and 23 to assist in turning the steering wheel 11 to the left.

Further, when the oil pressure in the pipe P1 increases under the above-mentioned throttling action of the servo valve 30 due to leftward rotation of the steering shaft 12, the oil pressure in the outflow passage 84 of the pump housing 80 increases. Correspondingly, the oil pressure in the oil chamber 86a of the boss 86 and the annular groove 92 of the valve 90 increases, and the oil pressure in the oil chamber 87a of the boss 87 increases. increases when the variable throttle valve 140 is fully closed. In addition, the pressure oil quantity digital voltage q from the function generator 180 increases in relation to the characteristic data Dqs in response to a decrease in the medium speed running state of the vehicle, and the digital opening voltage Vo from the function generator 190 increases. As the digital displacement voltage Vt from the A-D converter 150a and the digital pressure oil amount voltage Q from the function generator 180 increase, Voi decreases in relation to the map Ma, and the voltage from the function generator 200 decreases. The digital drive voltage VM increases in response to an increase in the digital pressure oil amount voltage Vq from the function generator 180 and the digital rotational speed voltage Vn from the A-D converter 170b in relation to the map Mb.

Then, the opening degree of the variable throttle valve 140 is determined by the function generator 190.
The amplification drive current of the power amplifier 190c under the control of the DA converter 190a and the V-1 converter 190b decreases as the digital opening voltage Vo decreases. The rotation speed increases as the digital drive voltage VM from the function generator 200 increases.
- Power increaser IM device 20 under the control of A converter 200a
It increases as the amplification drive voltage increases from 0b.

When the opening degree of the variable throttle valve 140 and the rotational speed of the DC motor M both increase in this way, the oil pressure in the oil chamber 87a of the boss 87 of the pump housing 80 increases as the opening degree of the variable throttle valve 140 increases. The eccentricity e of the cam ring 100 decreases due to the increased oil pressure in the oil chamber 86a acting on the control piston 133, the elastic force of the coil spring 123 acting on the control piston 122, and the oil chamber 86a. Based on the reduced eccentricity e, the oil pump P increases its rotational speed to supply pressure oil at an amount corresponding to the pressure oil amount digital voltage Vq. It is discharged into the pipe P1. This means that the power cylinder 20 can smoothly assist the leftward rotation of the steering wheel 11 when the vehicle is running at a medium speed based on an appropriate amount of pressure oil discharged from the oil pump P. means.

In such a case, as is easily understood from the above, both the notches 91a and 92a of the valve 90 and the balance groove 92b
Each hydraulic pressure within is the amount of pressure oil discharged from the oil pump P (i.e.,
Since both change in accordance with changes in the amount of pressure oil pumped by the oil pump P, the balanced state of each oil pressure in both notches 91a and 92a in relation to the oil pressure in the balance groove 92b is maintained in the same way as described above, and the pump Coaxial support between the cylinder 110 and the rotating shaft of the armature 70 can be ensured with high precision.

Further, substantially the same as described above, the opening degree of the variable throttle valve 140 and the rotation speed of the DC motor M are both map Ma.

Since it is determined in relation to Mb, the overall efficiency of the electric pump PM can be maintained high even when the steering wheel 11 is rotated to the left while the vehicle is running at a medium speed. This means that the power loss of this type of power steering device can be further reduced even when the steering wheel 11 is rotated to the left while the vehicle is running at a medium speed.

In addition, in the above description of the operation, the case where the steering handle 11 is rotated to the left is described, but instead of this, the case where the steering handle 11 is rotated to the right is also substantially the same as described above. similar effects can be achieved.

Further, in the embodiment, since the valve 90 rotatably supports the pump cylinder 110 coaxially with the rotation axis of the armature 70 as described above, the pump cylinder 11
It is possible to omit a bearing such as a ball hair ring for pivotally supporting the armature 70, and to ease the requirements for processing accuracy of the cylindrical part 110b of the pump cylinder 110 for coaxially supporting the rotating shaft of the armature 70, and to It is possible to omit the work of aligning the axis of the cylindrical portion 110b with respect to the rotation axis of the child 70.

Further, in the above embodiment, an example was described in which the rotation speed sensor 170 was used to detect the rotation speed of the DC motor M. However, instead of this, means for detecting the input voltage, input current, etc. of the DC motor M may be used. You may implement the adopted method.

Further, in the embodiment described above, the eccentricity e of the cam ring 100 was detected by the differential transformer 150, but instead of this, the potentiometer was detected by the control piston 12.
2 may be operatively connected to detect the eccentricity e.

Further, in the embodiment described above, the opening degree of the variable throttle valve 140 was controlled in inverse proportion to the inflow current, but instead of this, the linear actuator 141 controls the valve body 140.
The displacement amount of the valve seat 42a toward the valve seat 142b may be changed in inverse proportion to the inflow current.

Further, in the above embodiment, an example was described in which the present invention is applied to a DC motor and an oil pump that are integrally assembled coaxially within the tank housing 40, but the present invention is not limited to this, and various rotary electric motors that are independent of each other. The present invention may also be applied to an electric pump constructed by operatively connecting various oil pumps with appropriate compression rings.

[Brief explanation of drawings]

IT diagram ~ 3rd FI! J is the overall configuration diagram of the device of the present invention, No. 4
The figure is a cross-sectional view taken along line IV-IV in Figure 3, Figure 5 is a cross-sectional view taken along line V-V in Figure 3, and Figure 6 is a cross-sectional view taken along line V-V in Figure 3.
! Figure 7 is a cross-sectional view along line ■-■ in Figure 883, and Figure 8 is a cross-sectional view along line ■-■ in Figure 3.
A cross-sectional view along the line, Figure 9 is IX-IX in Figure ll88.
10 is a partial vertical sectional view of the oil pump in FIG. 3, and FIG. 11 is a digital pressure oil amount voltage representing the optimal oil discharge amount from the oil pump and a digital vehicle speed voltage representing vehicle speed. FIG. 12 is a map showing the relationship between the digital pressure oil amount voltage, the digital opening voltage representing the optimum opening of the variable throttle valve, and the digital displacement voltage representing the displacement of the differential transformer; 1st
Figure 3 is a map showing the relationship between the digital pressure oil amount voltage, the digital drive voltage required to drive the DC motor at an i-sequential rotation speed, and the digital rotation speed voltage representing the actual rotation speed of the DC motor, No. 14. The figure is a graph showing the relationship between actual rotation speed freezing and efficiency/maximum efficiency in a DC motor, and FIG. 15 is a graph showing the relationship between cam ring eccentricity and efficiency/maximum efficiency in an oil pump. Description of symbols 1O... Steering mechanism, 12... Steering shaft, 13... Steering wheel, 20... Power cylinder, 3o... Servo valve, 120, 130... Control piston mechanism, 140...・
・Variable throttle valve, 150...Differential transformer, 160...
・Vehicle speed sensor, 17°... Rotation speed sensor, 180.
190.200...Function ordering device, M...DC motor, P...Oil pump, PM...Electric pump.

Claims (1)

[Claims] It has a steering mechanism that operates in response to the rotation of the steering shaft of the vehicle to steer the steering wheels, and a variable displacement pump that generates pressurized fluid in an amount corresponding to the variable displacement in accordance with the rotational speed of the rotary electric motor. A power rudder comprising an electric pump, an assisting means for assisting the operation of the steering mechanism by being supplied with pressure fluid from the pump in response to rotation of the steering shaft, and a displacement control means for controlling a variable displacement of the pump. In the detection device, a first detection means detects the running speed of the vehicle and generates this as a first detection signal, a second detection means detects the rotational speed of the rotary electric motor and generates it as a second detection signal, a third detection means for detecting the variable displacement of the pump and generating this as a third detection signal; and a third detection means for detecting the variable displacement of the pump and generating the third detection signal;
The optimum pressure fluid supply amount is determined according to the value of the detection signal.
a first output signal generating means for generating an output signal, and a predetermined relationship between the optimum pressure fluid supply amount and the optimum rotational speed of the rotary electric motor under the optimum overall efficiency of the rotary electric motor and the pump; a second output signal generating means for determining the optimum rotational speed according to the value of the first output signal and generating it as a second output signal and applying it to the rotary electric motor; and the optimum pressure fluid supply amount under the optimum overall efficiency. third output signal generating means for determining the optimum variable displacement according to the value of the first output signal from a predetermined relationship between A power steering device for a vehicle equipped with a variable displacement electric pump.