KR19990011887A - Pump Load Release Device of Power Steering - Google Patents

Abstract

The present invention relates to a power steering apparatus of an automobile, and at the same time solves the hydraulic load of the oil pump and the engine speed decrease according to the increase in the oil pressure at the time of maximum power steering, and at the same time, the power steering action is smooth. It is an object of the present invention to provide a pump unloading device for power steering which can prevent the deterioration of steering and response sensitivity and also prevent damage to the power piston.

Therefore, the pump load releasing device of the power steering according to the present invention, when the power piston 8 is located at the left and right maximum stroke points (PL, PR), the end and the ring of the body (8a) of the power piston (8) 8b) connects the communication pipe 50 communicating with the first and second hydraulic chambers 10a and 10b of the power cylinder 10 at the point of contact between the communication cylinders 50 and the connection portion between the communication pipe 50 and the power cylinder 10, respectively. When the pressure of the hydraulic chambers 10a and 10b rises above a predetermined value and the power piston 8 reaches the maximum stroke point and comes into contact between the body 8a and the ring 8b. It is configured to install a valve body 60 for communicating the communication pipe 50 and the corresponding hydraulic chamber (10a, 10b), so that the valve body of the hydraulic chamber acting pressure during the power steering operation is open, the power piston When the valve moves to the maximum, the valve body on the opposite side is opened to communicate the first and second hydraulic chambers. It is one to release the pressure load acting on the pump.

Description

Pump Load Release Device of Power Steering

The present invention relates to a power steering apparatus for a vehicle, and more particularly, to release the hydraulic load of the oil pump according to the increase in the oil pressure at the time of the maximum power steering, and to release the engine speed by turning off the hydraulic cylinder in the power cylinder itself. The present invention relates to a pump load releasing device for power steering, which is suitable to prevent relief and noise relief of the hydraulic pump, and at the same time to perform such an operation smoothly and accurately.

In general, the power steering device of a vehicle is a device for reducing the operating force of the steering wheel by its backing action by installing a hydraulic power booster during the steering device, and the configuration thereof is schematically illustrated in FIG. 1. Similarly, the pinion shaft 2 connected to the steering wheel operated by the driver to rotate, the pinion shaft 2 is installed, the steering gear box 4 having a valve unit (not shown) therein, and It is meshed with gears of the pinion shaft 2 to convert its rotational motion into linear motion, and accommodates a steering rack 6 connected to the wheels by a predetermined link means, and a power piston 8 of the steering rack 6. The hydraulic cylinder 12 connected to the valve unit of the steering gear box 4 and supplying the operating oil to the power cylinder 10 by the driving force of the engine; And it consists of a reservoir 14 for charging.

In FIG. 1, reference numerals 16a and 16b denote first and second hydraulic pipes connecting the valve unit of the steering gear box 4 and the power cylinder 10 to the first and second hydraulic pipes 16a and 16b. 16b) communicates with the power cylinder 10 at a position slightly outside the stroke section L of the power piston 8, and supplies operating oil to the first and second hydraulic chambers 10a and 10b of the power cylinder 10, respectively. Done.

Briefly describing the operation of the power steering apparatus as described above, when the steering wheel is rotated, the pinion shaft 2 is rotated to the left or right, so that the steering rack 6 and its power piston 8 are moved to the left or right. At this time, the path of the operating oil supplied from the hydraulic pump 12 is changed by the valve unit in the steering gear box 7 so that the high pressure operating oil passes through the first hydraulic pipe 16a or the second hydraulic pipe 16b. By flowing into the first hydraulic chamber 10a or the second hydraulic chamber 10b of the power cylinder 10, the power piston 8 is moved left or right, and the steering rack 6 is moved left or right, and the wheel Will reverse the direction of.

In this process, the driver's power to rotate the steering wheel is reduced and can easily turn.

However, when the steering wheel is rotated as much as possible in the right direction (for example, only the right direction and the operation in the left direction is the same) in the power steering device, the power piston 8 is In the drawing, the operating oil is continuously supplied to the power cylinder 10 by the hydraulic pump 12 at the point where it is located at the maximum stroke points PL and PR in the right direction, but the power piston 8 is no longer moved. do. As a result, the pressure of the first hydraulic chamber 10a of the power cylinder 10 is rapidly increased, and the phenomenon in which the hydraulic pump 12 is overloaded due to the increase in pressure thereof occurs.

Since such overload requires additional power of the engine in the hydraulic pump 12, the engine is eventually loaded, and in particular, in the case of engine idling, the engine speed drops sharply or the starting is turned off. In addition, the hydraulic pump 12 applied to the power steering is provided with a relief valve for releasing some pressure by returning the operating oil when the pressure of the operating oil rises, and when the pressure rises, the operating oil escapes through the relief valve. There is a problem that annoying noise caused by.

In order to solve such a problem, it is conventionally provided that a pressure sensing switch is installed in a power steering apparatus, and an apparatus for preventing starting off by increasing the output of the engine according to the detection signal of the pressure sensing switch is disclosed. have. However, this is one way to prevent starting off, but the overall cost burden and high consumption of fuel, in particular, the problem of overloading the hydraulic pump and the engine has a disadvantage that can not fundamentally solve.

In addition, there is a pressure releasing device disclosed by Utility Model Registration No. 96-101766 (Application No. 94-32451) granted to the present applicant, which releases the pressure in communication with the power cylinder at the maximum stroke of the power piston. When the hydraulic piston is installed and the power piston moves to the left or right to the maximum and passes the pressure relief hydraulic pipe part, the pressure relief hydraulic pipe is allowed to escape the operating oil and return to the oil reservoir. For example, when the power piston moves to the first cylinder side as much as possible and starts to move in the opposite direction again, the first hydraulic chamber and the second hydraulic chamber of the power cylinder communicate with the first hydraulic tube and the pressure releasing hydraulic tube, respectively. The high pressure working oil is introduced into the first and second hydraulic chambers. In this case, the pressure acting on the second hydraulic chamber escapes to the second hydraulic tube, but its operation is not rapid. Therefore, the steering force acts as a resistance to steering until the power piston exits the pressure relief hydraulic tube. And a problem that the response sensitivity is lowered. Also, the power cylinder has a hole for communication with the pressure releasing hydraulic pipe, and the power piston must pass through the hole, and thus the power piston It has the disadvantage of hydraulic leakage caused by the sharp circumference of this hole.

The present invention has been made to solve the problems of the prior art as described above, and at the same time fundamentally solve the hydraulic load of the oil pump according to the increase in the oil pressure at the time of power steering and the resulting engine speed decrease, It is an object of the present invention to provide a pump load releasing device for power steering, which can prevent steering wheel deterioration and response sensitivity by smoothly and accurately performing steering action and also prevents damage to the power piston.

According to this object, the pump load releasing device of the power steering system according to the present invention, when the power piston is located at the left and right maximum stroke point, the first of the power cylinder at the point of contact between the body end of the power piston and the ring 2, connecting a communication tube communicating with the hydraulic chamber, and the connection between the communication tube and the power cylinder is connected between the body and the ring when the pressure of each hydraulic chamber is increased above a predetermined value and the power piston reaches the maximum stroke point. It is characterized in that it is configured to install a valve body for opening the operation when the contact with the communication pipe and the corresponding hydraulic chamber to communicate.

1 is a view showing a configuration and a power cylinder structure of a general power steering apparatus

Figure 2 is a cross-sectional view of the power cylinder for showing the pump load releasing device according to the present invention

3 is a sectional view showing a first embodiment of a valve body according to the present invention;

4 is a sectional view showing a second embodiment of a valve body according to the present invention;

5 is a view showing an operating state of the pump load releasing device according to the present invention, a view showing a state in which the steering rack to the left to release the pressure

Explanation of symbols for main parts of the drawings

8: Power piston 8a: (Power piston) body

8b: (power piston) ring 10: power cylinder

10a, 10b: 1st, 2nd hydraulic chamber 12: through-hole

50: communicating tube 60: valve body

62: valve body 62a: guide groove

64: ball 66: elastic body

68: valve plate body

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The same reference numerals are given to the same parts as in FIG. 1, and repeated descriptions thereof will be omitted.

2 is a cross-sectional view showing a pump load releasing device of the power steering according to the present invention, as shown in the power cylinder 10, the power piston 8 is to be located at the left and right maximum stroke points (PL, PR) At the time of contact between the end of the body 8a of the power piston 8 and the ring 8b, a communication tube 50 communicating with the first and second hydraulic chambers 10a and 10b of the power cylinder 10 is connected. do.

Here, the ordinary power piston 8 is composed of a body 8a and a ring 8b circumferentially fixed in the middle of the body 8a, which ring 8b is usually a hard synthetic resin (especially a Teflon resin). ) Therefore, the power piston 8 is in close contact with the inner wall of the power cylinder 10 through its ring 8b. In the above description of the configuration of the present invention, the connection position of the communication tube 50 is, in other words, the power piston. When (8) reaches the maximum stroke point (PL, PR), it is positioned at an arbitrary point between the end of its body (8a) and the ring (8b), in other words, the power piston (8) is left or right Even if it moves to the maximum, the ring 8b of the power piston 8 does not pass the through hole 12 of the power cylinder 10 so as to prevent damage to the ring 8b by the through hole 12.

In addition, the present invention is configured by installing the valve body 60 in the connection portion between the communication tube 50 and the power cylinder 10, the valve body 60 is the pressure of each of the hydraulic chamber (10a, 10b) is small When it rises above stationary, it opens by this pressure, and the hydraulic chamber 10a or 10b of the higher pressure is made to communicate with the communication pipe 50. As shown in FIG. In addition, when the valve body 60 comes into contact with the body 8a and the ring 8b of the power piston 8 when the power piston 8 reaches the maximum stroke point (PL, PR). In addition, the communication tube 50 acting on the hydraulic chamber 10a or 10b in the higher pressure side is brought into the hydraulic chamber 10a or 10b in the lower pressure side to release the pressure.

3 and 4 show the first and second embodiments of the valve body 60 described above, and the valve body 60 according to the present invention includes the hydraulic chambers 10a and 10b of the power cylinder 10. It is a mechanical valve body that is opened by pressure and opened by direct contact with the power piston 8, so that it can be easily applied at low cost.

First, in the case of FIG. 3, the valve body 62 connecting the communication tube 50 and the power cylinder 10 and the valve body 62 are accommodated in the through hole 12 of the power cylinder 10. That is, it consists of a ball 64 which protrudes a predetermined amount inside the power cylinder 10 while spherical contacting, and the elastic body 66 which supports this ball 64. The valve body 60 according to the first embodiment is always closed by the elastic force of the elastic body 66 until a pressure of a predetermined value or more is applied to the hydraulic chambers 10a and 10b of the power cylinder 10. On the other hand, when contacted with the power piston (8) is pressed by the body (8) of the piston (8) is opened. Here, the elastic force of the elastic body 66 is set to be lower than the relief valve set pressure of the hydraulic motor 12 so that the valve body 60 is opened before the relief valve is opened. Thereby, the pressure rise can be released before the hydraulic pump 12 is overloaded. Only when the release point is not moving the power piston 8 and the power piston 8 reaches the maximum stroke point (PL, PR) is released only when the valve body 60 on the opposite side is released to release the pressure during the return Will not occur.

The valve body 60 in this first embodiment has a simple configuration and accurate operation.

The valve body 60 according to the second embodiment of FIG. 4 moves in the valve body 62 connecting the communication tube 50 and the power cylinder 10 and the guide groove 62a of the valve body 62. It consists of a curved thin plate-shaped valve plate body 68 which is possibly accommodated and protrudes a predetermined amount into the power cylinder 10 while in contact with the through hole 12 of the power cylinder 10. The valve body 50 eliminates the elastic body 66 in the first embodiment, and has a simple configuration in which a thin valve plate body 68 is applied instead of the ball 64. The valve plate body 68 Irrespective of the absolute pressure of the first and second hydraulic chambers 10a and 10b, the side with the higher pressure is always opened due to the pressure fluctuations of the hydraulic chambers 10a and 10b.

Figure 5 is a view for explaining the operation of the pump pressure releasing device of the power steering of the present invention made as described above, will be described on the basis of the case that the power piston 8 moves to the left side, this operation to the right Follow the process. In addition, the case where the valve body 60 which concerns on 1st Embodiment is applied is demonstrated first.

First, when the steering wheel is rotated to the left in order to change the driving direction of the vehicle to the left, the pinion shaft 2 rotates to the left. Accordingly, the steering rack 6 and the power piston 8 try to move to the left. The path of the operating oil pumped from the hydraulic pump 12 is changed by the valve unit in the steering gear box 4 so that the high pressure of the hydraulic cylinder 12 is transferred to the second hydraulic chamber 10b of the power cylinder 10 through the second hydraulic pipe 16b. The operating oil is supplied, and the operating oil in the first hydraulic chamber 10a is returned to the oil reservoir 14 so that the power piston 8 and the steering rack 6 start moving to the left. In the state where the power piston 8 has moved a predetermined distance, the pressure in the second hydraulic chamber 10b rises above the set pressure of the elastic body 66 of the valve body 60, so that the ball 64 of the valve body 60 is moved. By retreating, the 2nd hydraulic chamber 10b and the communication pipe 50 are made to communicate. Accordingly, the high pressure operating oil acts on the second hydraulic chamber 10b and the communication tube 50. On the other hand, the pressure increase of the second hydraulic chamber 10b is increased as the power piston 8 approaches the left maximum stroke point PL, thereby applying a load to the hydraulic pump 12 and the engine.

In this process, as the power piston 8 approaches the left maximum stroke point PL, the body 8a of the power piston 8 comes into contact with the ball 64 of the valve body 60, and the maximum stroke point ( In the state of maximum movement to PL), the ball 64 is pushed completely to completely open the through-hole 12 of the power cylinder 10, and accordingly, the high-pressure operating oil supplied to the second hydraulic chamber 10b receives the first hydraulic pressure. It is sucked into the seal 10a and returned to the oil reservoir 14 through the first hydraulic pipe 16a. That is, the hydraulic oil pumped by the hydraulic pump 12 to the second hydraulic pipe 16b and the second hydraulic chamber 10b is the communication pipe 50, the first hydraulic chamber 10a and the first hydraulic pipe 16a. Since it is immediately returned to the oil reservoir 14 through the second hydraulic chamber (10b) is the pressure rise is released, and eventually do not put a load on the hydraulic pump 12 and the engine. In this case, since the pressure of the second hydraulic chamber 10b is always kept lower than the relief valve set pressure of the hydraulic pump 12, the relief valve of the hydraulic pump 12 and its circuit configuration are practically unnecessary.

When the steering wheel is turned to the right again in the above state, the high pressure operating oil by the hydraulic pump 12 flows into the first hydraulic chamber 10a and is not completely closed by contact with the power piston 8. Flows into the gap between the ball 64 and the through-hole 12 of the power cylinder 10 and closes the valve body 60 on the right side. In addition, as soon as the power piston 8 is separated from the ball 64 in an instant, the valve body 60 on the left side is also closed by the elastic force of the elastic body 66. When the pressure in the first hydraulic chamber 10a rises further, the valve body 60 on the left side is opened, and thereafter, the first hydraulic chamber 10a is subjected to the same process as when the power piston 8 moves to the left side. Will be released.

On the other hand, when the valve body 60 according to the second embodiment is applied, unlike the first embodiment, since there is no elastic body 66, each valve body 60 is closed or open when no steering is performed. do. This is because the operating oil is circulated only to the hydraulic pump 12 and the oil reservoir 14 due to the routing of the valve unit of the steering gear box 4 if the steering wheel is not operated. Because there is no flow.

When the driver rotates the steering wheel to the left for the return of the vehicle, the high-pressure operating oil is supplied to the second hydraulic chamber 10b of the power cylinder 10, as described above, and is located in the first hydraulic chamber 10a. The working oil is returned to the oil reservoir 14. At this time, the valve plate body 68 of the second hydraulic chamber 10b having a high pressure regardless of the moving distance of the power piston 8 or the degree of pressure increase due to the pressure difference between the first and second hydraulic chambers 10a and 10b. ) Is opened, and the valve plate body 68 on the side of the first hydraulic chamber 10a having a lower pressure is closed by the operating oil pressure of the second hydraulic chamber 10b. Subsequently, the power piston 8 is positioned at the left maximum stroke point PL and the valve plate body 68 on the side of the first hydraulic chamber 10a is pressed to open the first hydraulic chamber 10a and the second hydraulic chamber 10b. By communicating with each other, excessive pressure rise in the second hydraulic chamber 10b and subsequent release of the load on the hydraulic pump 12 and the engine.

In addition, in all the above processes, the valve body 60 comes into contact only with the body 8a of the power piston 8, and there is no risk of damaging the ring 8b because there is no contact with the ring 8b. No pressure leak occurs. In addition, since the pressure of the operating oil acts only on one side of the hydraulic chamber at the beginning of the movement of the power piston 10 located at the maximum stroke point, the initial steering and response sensitivity are improved.

As described above, according to the pump load releasing device of the power steering according to the present invention, the problem of the hydraulic load of the oil pump and the engine speed decrease according to the increase in the oil pressure at the maximum stroke of the power steering is basically solved. In addition, by performing the power steering operation smoothly and accurately, it is possible to prevent the deterioration of steering and response sensitivity, and also to prevent damage to the power piston.

Claims (4)

In the power steering apparatus of an automobile, When the power piston 8 is located at the left and right maximum stroke points PL and PR, the power cylinder 10 of the power cylinder 10 is in contact with the end of the body 8a of the power piston 8 and the ring 8b. The communication pipe 50 which connects the 1st, 2nd hydraulic chamber 10a, 10b is connected, and the pressure of each hydraulic chamber 10a, 10b is predetermined value in the connection part of this communication pipe 50 and the power cylinder 10. When it is raised above and when the power piston 8 reaches the maximum stroke point (PL, PR) and comes into contact between the body (8a) and the ring (8b), the opening operation is performed to correspond to the communication tube (50). A pump load releasing device for power steering, characterized by providing a valve body (60) for communicating hydraulic chambers (10a, 10b). The method of claim 1, The valve body 60 is a valve body 62 that connects the communication tube 50 and the power cylinder 10, and is accommodated in the valve body 62 to be in contact with the through hole 12 of the power cylinder 10. And a ball (64) projecting a predetermined amount into the power cylinder (10), and an elastic body (66) holding the ball (64). The method of claim 2, The elastic body 66 is a pump unloading device of the power steering, characterized in that the pressure of the hydraulic chamber (10a, 10b) is set to a repulsive force to be retracted before reaching the opening pressure of the relief valve of the hydraulic pump 12 . The method of claim 1, The valve body 60 is accommodated in the valve body 62 for connecting the communication pipe 50 and the power cylinder 10 and the guide groove 62a of the valve body 62 to be movable to the power cylinder ( And a curved thin plate-shaped valve plate body (68) projecting a predetermined amount into the power cylinder (10) while being in contact with the through hole (12).