JPH0427671A - Car speed-sensitive type power steering control device - Google Patents

Abstract

PURPOSE:To provided an excellent moderate feeling for steering during high speed running by providing an oil pressure source mounted on a rotary part rotated according to a car speed and controlling an oil pressure, outputted from the oil pressure source, so that the rate of a change of an oil pressure when a car speed is high is increased to a value higher than that when a car speed is low. CONSTITUTION:An engine-driven vane pump 3 is connected to a rotary valve 43 of a gear box 7 through an oil passage 41. The steering pressure of the rotary valve 43 fed through switching operation occasioned by operation of a handle by a driver is fed to and discharged from hydraulic cylinders 29 and 31 on both sides through oil passages 45 and 47, respectively. In this case, a reaction force pressure control device 15 comprising a first trochoid pump 51, a second trochoid pump 53, and a three-port two-position switching valve 55, which are respectively driven by an output shaft 50, the peripheral velocity of which is adjusted to a value proportioning a car speed, is connected to a transmission 13. The reaction force pressure of the pump 51 delivering an oil pressure (reaction force pressure) proportioning a car speed is fed to a reaction force camber 61 and fed as a switching signal pressure to the switching valve 55, and an oil pressure from a pump 53 through the switching valve 55 is fed to a reservoir 19 or the reaction force chamber 61.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a vehicle speed-sensitive power steering device used in an automobile steering system, and more particularly to a vehicle speed-sensitive power steering control device that improves the reaction pressure characteristics of hydraulic pressure supplied to a reaction chamber.

[Conventional technology]

As shown in FIG. 4, the conventional vehicle speed sensitive power steering control device 100 includes a supply oil passage 103 that connects an oil pump 101 and a rotary valve 102, and a discharge oil passage that communicates between the rotary valve 102 and a reservoir 105. 1
07, and a reaction oil fml13 that communicates the reaction chamber 109 and the trochoid pump 111. The trochoid pump 111 is connected to the a-shaft of the transmission (not shown), and applies hydraulic pressure (reaction pressure) that increases linearly as the vehicle speed increases to the reaction chamber 10 as shown in FIG.
9. This conventional vehicle speed-sensitive power steering control device is described in detail in ``Toyota Hiace New Model Manual Part No. 61559J (Published: August 24, 1988).

[Problem B that the invention attempts to solve]

However, in the conventional vehicle speed-sensitive power steering control device shown in Fig. 4, the reaction pressure supplied to the reaction force chamber changes linearly (constantly) with the vehicle speed, so the steering force The rate of change is also linear (constant) with respect to vehicle speed.
As a result, the steering reaction force from the road surface decreases, the steering becomes less sharp when the vehicle is running at high speed, and the steering feeling is not very favorable. Furthermore, in the trochoid pump connected to the output shaft of the transmission, as the vehicle speed increases, the pump loss due to pressure oil leakage within the pump increases, causing the discharge pressure to reach a plateau. As a result, as the vehicle speed increases, the rate of increase in reaction pressure becomes smaller than when the vehicle speed is low, and the steering at high speeds lacks sharpness, resulting in an unfavorable steering feel. Therefore, an object of the present invention is to increase the rate of change of the pressure oil when the vehicle speed is high compared to the rate of change of the pressure oil when the vehicle speed is low compared to the rate of change of the reaction force pressure when the vehicle speed is low. The objective is to provide a sense of sharpness in steering.

[Means to solve the problem]

Therefore, the vehicle speed-sensitive power steering control device of the present invention includes a hydraulic power source, a switching valve that communicates with the hydraulic power source and controls the supply and discharge of hydraulic pressure to the left and right hydraulic cylinders, and a hydraulic pressure source that supplies hydraulic pressure according to the vehicle speed. In a vehicle speed-sensitive power steering device equipped with a reaction force chamber, a second hydraulic pressure source is attached to a rotating part that is linked to the vehicle speed, and the hydraulic pressure output from this second hydraulic source is controlled when the vehicle speed is low. The vehicle is equipped with a control valve means for controlling the rate of change in oil pressure when the vehicle speed is high compared to the rate of change in the oil pressure, and the reaction pressure output from the control valve means is supplied to the reaction force chamber. It is characterized by

[Effect]

The control valve means of the vehicle speed sensitive power steering control device in this means increases the rate of change in the oil pressure discharged from the second oil pressure source when the vehicle speed is high compared to the rate of change in the oil pressure when the vehicle speed is low. , non-linear, or multi-stage polygonal line characteristics (reaction force pressure), and the reaction pressure is supplied to the reaction chamber, so this vehicle speed-sensitive power steering control device can handle high vehicle speeds compared to low vehicle speeds. At times, the rate of increase in reaction force pressure increases as the vehicle speed increases, resulting in a more crisp steering feel and a more responsive steering feel.

【Example】

Hereinafter, one embodiment of the present invention will be described based on the drawings. FIG. 1 is a layout diagram showing the arrangement of parts of a vehicle speed-sensitive power steering control device, and reference numeral 1 indicates an engine. The vane pump 3 driven by the engine 1 is connected via a pipe 5 to a gear box 7 provided with a rotary valve and a reaction chamber described later, and supplies steering hydraulic pressure to the gear box 7. The gearbox 7 is connected to a reaction pressure control device I5 mounted on the transmission 13 via a pipe 9.11,
Reaction pressure is supplied through piping 9, and oil (in a non-pressurized state) is supplied through piping 11. This reaction pressure control device 15 is connected to a reservoir 19 via a pipe 17 and discharges hydraulic pressure to the reservoir 19. Reservoir 19
is connected to the vane pump 3 via piping 21, and supplies unpressurized oil to the vane pump 3. Further, the reservoir 19 is connected to the gear box 7 via a pipe 23 so that the steering pressure is discharged from the gear box 7. Gear box 7 has piping 25.2
7 to the left and right hydraulic cylinders 29.31,
When steering pressure is supplied to one of the hydraulic cylinders 29.31,
The steering pressure supplied to the other of the hydraulic cylinders 29 and 31 is discharged to the reservoir 19 via the pipe 23. Next, a more detailed explanation will be given with reference to FIG. 2 showing the hydraulic circuit of the vehicle speed sensitive power steering control device. The vane pump 3 driven by this engine 1 has an oil passage 41 (
It is connected to a rotary valve (switching valve) 43 of the gear box 7 through a pipe 5 (including piping 5), and supplies steering pressure to the rotary valve 43. As is well known, this rotary valve 43 is switched and operated by the driver's handle operation, and the supplied steering pressure is transferred to the left and right oil pressures via an oil passage 45 (including piping 25) and an oil passage 47 (including piping 27). cylinder 29.31
The supply/discharge switching operation is performed. Hydraulic cylinder 2
When the steering pressure is supplied to the hydraulic cylinder 3
The steering pressure of 1 is discharged to the reservoir 19 via the rotary valve 43 and the oil passage 49 (including the piping 23). Further, when the steering pressure is supplied to the hydraulic cylinder 31, the steering pressure of the hydraulic cylinder 29 is discharged to the reservoir 19 via the rotary valve 43 and the oil passage 49 (including the piping 23). . Reaction pressure control device 1 attached to transmission 13
5 is mainly composed of a first trochoid pump 51 and a second trochoid pump 53, which are each driven by an output shaft 50 whose circumferential speed is proportional to the vehicle speed, and a three-bottom, two-position switching valve 55. . The first trochoid pump 51 sucks the unpressurized oil from the reservoir 19 through the oil passage 57 (including piping 11), and
Discharges hydraulic pressure (reaction pressure) proportional to vehicle speed. This discharged reaction pressure is transferred to the reaction force chamber 6 through an oil passage 59 and an oil passage 60.
1 and is also supplied to 3 ports 2 via oil passage 63.
It is supplied to the position switching valve 55 as a switching signal pressure. Next, the second trochoid pump 53 sucks unpressurized oil from the reservoir 19 through the oil passage 57 and the oil passage 65, and discharges oil pressure into the oil passage 67 in proportion to the vehicle speed. This discharged hydraulic pressure is applied to the oil passage 69 (
(including piping 17) to reservoir 19. When the reaction pressure of the oil passage 63 rises to the specified pressure (set vehicle speed),
The three-bottom, two-position switching valve 55 is switched to the lower state shown in the figure, and the oil pressure in the oil passage 67 is supplied to the oil passage 71, and the oil passage 59,
A reaction pressure that is combined with the discharge pressure of the first trochoid pump is supplied to the reaction chamber 61 via the oil passage 6o. Note that the relief valve 73 disposed between the oil passage 59 and the oil passage 57 regulates the maximum pressure of the reaction pressure, and if the reaction pressure exceeds the maximum pressure, the oil passage 59 is The safety of the hydraulic circuit is ensured by discharging the reaction pressure to the negative pressure oil path 57. Furthermore, the fixed orifice 75 provided in the oil passage 59 ensures the generation of reaction pressure when the vehicle is stationary or stopped. Additionally, an orifice 76 provided between the oil passage 59 and the oil passage 57
The rate of change in reaction pressure can be adjusted by appropriately adjusting the orifice diameter. Next, the functions and effects of this embodiment will be described using FIGS. 2 and 3. Note that FIG. 3 is a hydraulic characteristic diagram of vehicle speed and reaction pressure. When the vehicle is stationary and in a low speed region (below the set vehicle speed), the reaction pressure discharged by the first trochoid pump 51 remains constant as the vehicle speed increases, as shown by A in FIG. increases at a rate of change, and via oil passages 59 and 60,
The reaction force chamber 61 is further supplied with a 3-point/2-position switching valve 5.
5 through an oil passage 63. However, since the reaction pressure is below the specified pressure, the 3-bot 2-position switching valve 55
is in the upper state shown in FIG. Therefore, the discharge oil pressure of the second trochoid pump 53 is
It is discharged into the reservoir 19 via the position switching valve 55 and the oil passage 69. As a result, the reaction force pressure supplied to the reaction force chamber 61 has a low rate of change characteristic as shown in FIG. 3A, depending on the discharge amount of the first trochoid pump 51. In this way, since only a small amount of low reaction force pressure acts on the reaction force chamber 61, the steering wheel can be steered with a light steering torque, and a light steering feeling can be obtained. Next, when the vehicle is in a medium/high speed range (above the set vehicle speed), the reaction pressure discharged by the first trochoid pump 51 remains constant as the vehicle speed increases, as shown by A in FIG. increases at a rate of change of
is supplied through the oil passage 63. And this oil passage 63
Since the reaction pressure is equal to or higher than the specified pressure, the three-bottom, two-position switching valve 55 is in the state shown in the lower diagram in FIG. Therefore, the discharge oil pressure of the second trochoid pump 53 is
The oil is supplied to the reaction force chamber 61 via the bottom two-position switching valve 55, the oil passage 71, the oil passage 59, and further the oil passage 60. As a result, the reaction pressure supplied to the reaction force chamber 61 is determined by the sum of the discharge amount of the first trochoid pump 51 and the discharge amount of the second trochoid pump 53, and has a high rate of change characteristic as shown in FIG. 3B. becomes. Since the reaction force pressure acting on the reaction force chamber 61 is high and the amount of change is large in this way, a sense of sharpness in steering can be obtained, and the effect of improving the steering feeling is provided. Furthermore, the vane pump 3 can be made smaller and lighter by separately configuring the vane pump 3, which serves as a hydraulic source for steering pressure, and the first trochoid pump 51 and second trochoid pump 53, which serve as hydraulic sources for reaction pressure. For example, one
This has the effect of greatly reducing space constraints for vehicles such as box cars, which have high engine room capacity constraints. Furthermore, a first trochoid pump 5 is used as a hydraulic source for reaction pressure.
Since the trochoid pump 1 and the second trochoid pump 53 are provided, the capacity and discharge characteristics of each trochoid pump can be changed to extremely easily provide a vehicle speed-sensitive power steering control device that provides a steering feeling that is optimal for the vehicle characteristics. It has an effect that can be used. For example, if the discharge volume of the first trochoid pump 5 is extremely small and the discharge volume of the second trochoid pump 53 is extremely large, in the stationary and low speed ranges, steering can be performed with a very light steering torque, and in the medium and low speed ranges, the In the high speed region, a very sharp feeling and a high reaction force can be obtained, making it possible to obtain a stable steering feeling. Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and can be implemented in various ways within the scope of the claims.
is included. For example, in this embodiment, the reaction pressure has a two-stage folding characteristic by switching with the three-point, two-position switching valve 55; It becomes possible to make it a characteristic. In addition, in the example, the reaction force pressure has a two-step bending characteristic, but
By using the bottom two-position switching valve 55 as an electromagnetic flow valve, it is also possible to make the reaction pressure have non-linear characteristics. [Effects of the Invention] As described above, according to the present invention, the rate of change in the oil pressure when the vehicle speed is high is greater than the rate of change in the oil pressure when the vehicle speed is low compared to the rate of change in the reaction pressure when the vehicle speed is low. Vehicle speed sensitive power steering control bag! Compared to when the vehicle is running at low speeds, the steering wheel operation becomes more crisp and direct at high speeds, providing a more direct steering feel.

[Brief explanation of drawings]

Figures 1 to 3 relate to an embodiment of the present invention, in which Figure 1 is a layout diagram showing the arrangement of parts of a vehicle speed sensitive power steering control device, and Figure 2 is a hydraulic circuit of a vehicle speed sensitive power steering control device. Fig. 3 is a hydraulic characteristic diagram of reaction pressure and vehicle speed, Fig. 4 is a hydraulic circuit diagram of a conventional vehicle speed sensitive power steering control device, and Fig. 5 is a hydraulic characteristic diagram of reaction pressure and vehicle speed of conventional technology. It is a hydraulic characteristic diagram. 3 ・ 29 ・ 31 ・ 43 ・ 50 ・ 51 ・ 53 ・ 55 ・ 61 ・ ・Vane pump (hydraulic source) ・Hydraulic cylinder ・Hydraulic cylinder ・Rotary valve (switching valve) ・Output shaft (rotating part) ・First trochoid pump ( 2nd hydraulic power source), 2nd trochoid pump (2nd hydraulic power source), 3-bottom 2-position switching valve (control valve means), reaction chamber

Claims (1)

[Claims] (1) Vehicle speed sensitive type that includes a hydraulic pressure source, a switching valve that communicates with the hydraulic pressure source and controls the supply and discharge of hydraulic pressure to the left and right hydraulic cylinders, and a reaction chamber that is supplied with hydraulic pressure according to the vehicle speed. In a power steering device, there is a second hydraulic pressure source attached to a rotating part that is linked to the vehicle speed, and the hydraulic pressure output from the second hydraulic source is compared with the rate of change of the hydraulic pressure when the vehicle speed is low when the vehicle speed is high. A vehicle speed-sensitive power steering control device comprising: a control valve means for controlling a rate of change in oil pressure to be increased; and a reaction pressure output from the control valve means is supplied to a reaction chamber. .