JPH0337056B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a variable damping force hydraulic shock absorber capable of adjusting damping force.

BACKGROUND ART Conventional hydraulic shock absorbers of this type include a swinging motor, a transmission mechanism that changes the speed and transmits the rotation of the motor to a damping force adjustment adjuster, and rotation of the adjuster. Since a detection sensor for detecting the angular position was installed outside the piston rod, mud or rainwater could enter the motor or transmission mechanism while the vehicle was running after this hydraulic shock absorber was installed on the vehicle body. In addition to damaging these components, there were other problems such as the need for special installation space to attach the motor, transmission mechanism, etc. to the vehicle body.

Therefore, in order to eliminate the above-mentioned problems, the applicant has proposed a hydraulic shock absorber in which a motor, transmission mechanism, etc. are housed inside a piston rod (for example, Japanese Patent Application No. 1984-21848). .

Problems to be Solved by the Invention However, in the case of conventional hydraulic shock absorbers,
In order to detect the rotation angle position of the adjuster and stop it at a predetermined rotation position, a detection sensor and a brake circuit installed inside or outside the piston rod are used, so the structure is complicated and expensive. Therefore, the structure is simple, and
It was hoped that an inexpensive hydraulic shock absorber would appear.

In addition, in the case of a motor configured to stop the motor using a brake circuit as described above, it is difficult to accurately control the stop position of the regulator.
There is a possibility that large variations in stopping positions may occur.
Therefore, the diameter of the orifice, which is determined by the relative relationship between the through hole of the adjuster and the communicating hole of the stud, must be set relatively small. As a result, the degree of freedom in varying the damping force is restricted, and the soft damping force effect becomes particularly small. Furthermore, the control method using a brake circuit requires a braking angle that depends on the rotational speed of the motor, so the motor rotational speed cannot be increased and the damping force switching time is relatively long. There is a problem.

Therefore, as in the technique described in, for example, Japanese Patent Application Laid-Open No. 58-50339, an adjuster for opening and closing the opening/closing orifice is provided at the lower end of the control rod, while a protrusion is provided protruding from the inner surface of the stud. It has also been devised that the rotation angle of the adjuster is restricted by a protrusion. However, in this conventional example, a pair of solenoids arranged at the upper end of the piston rod and a rack and pinion that directly transmits the driving force of the solenoid to the adjuster are used as the rotary drive mechanism of the adjuster. Therefore, in this case as well, it becomes difficult to accurately control the stop position of the adjuster. That is,
If a driving solenoid is directly and suddenly stopped (collided with) by the above-mentioned protrusion, there is a risk that it will return in the opposite direction due to a repulsive force proportional to the collision speed. Therefore, the control of the stop position of the adjuster becomes unstable, and the orifice cannot be properly opened and closed.

Means for Solving the Problems The present invention has been devised in view of the above-mentioned conventional problems, and in particular, the present applicant detects an overload current flowing through the motor and stops the rotation of the motor. If we focus on the technology (for example, well known from Japanese Patent Application Laid-open No. 132533/1983) and use this technology in the damping force variable device of a hydraulic shock absorber, the control circuit will be simplified and a detection sensor will not be necessary. This is why we have taken this into account. In particular, a motor control section is provided which detects an overload current state of the motor and stops the rotation of the motor, and also controls the rotational position of the final output shaft of the reduction gear at a predetermined angular position via a stationary member within the piston rod. By regulating
The present invention is characterized in that a stopper mechanism is provided that allows the adjuster to rotate only within a predetermined angular range, and the adjuster is configured to open an orifice at at least one end position of the predetermined angular range.

Effect: The stopper mechanism of the present invention can detect a motor overload current state that occurs when the rotation of the regulator is stopped and brake the rotation of the motor, thereby simplifying the overall structure of the device. Of course, as mentioned above, when the rotation of the adjuster is suddenly stopped by the stopper mechanism, it tries to rotate in the opposite direction due to the repulsive force, but this reverse rotational force is transmitted to the reduction gear and motor. In other words, the rotational force from both forward and reverse directions interferes within the reduction gear, suppressing the reverse rotational force, thereby stably and reliably stopping the adjuster at the appropriate stop position. be able to.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a partially cutaway sectional view showing an embodiment of a hydraulic shock absorber according to the present invention, FIG. 2 is a sectional view taken along the - line in FIG. 1, and FIG. 3 is an enlarged view taken along the - line in FIG. 1. be.

In FIG. 1, 1 is a cylinder filled with hydraulic fluid, and this interior is formed inside an outer cylinder 2 that surrounds the outer periphery of the cylinder 1 at the bottom (not shown) of the cylinder 1. It communicates with a reservoir chamber 3 for hydraulic fluid. Reference numeral 4 denotes a cylindrical piston rod that sealingly penetrates approximately the center of a guide member 5 provided at one end 1a of the cylinder 1 and protrudes to the outside. Reduction gears 8, which are transmission mechanisms that change the speed and transmit the rotation of the motor 7 to the adjuster 6, are respectively housed. A swinging rod 9 is fixed to the final drive shaft 8a of this reduction gear 8. On the other hand, stopper pins 10 and 11 are implanted in the gear case 12, which is a stationary member, at predetermined intervals in the circumferential direction. The swinging rod 9 and the stopper pins 10 and 11 constitute a stopper mechanism 13. In addition, the stopper pins 10 and 11 are
It may be directly fixed to the cylindrical wall of the piston rod 4.

On the other hand, 14 and 15 are used to elastically prevent the swinging rod 9 from rotating before the swinging rod 9 collides with the stopper pins 10 and 11. It is an elastic body disposed between them and is fixed to the stopper pins 10 and 11 side. In this embodiment, coil springs are used as the elastic bodies 14 and 15, but the present invention is not limited to this, and for example, plate springs may be used. Reference numeral 16 denotes a motor control that detects an overload current state of the motor 7 that occurs when the swinging rod 9 contacts the stopper pins 10, 11 via the elastic bodies 14, 15, and brakes the rotation of the motor 7. 17 is a damping force setting device for setting a desired damping force, and is connected to a motor drive circuit 18.

Next, 19 is a cylinder 1 for separating the inside of the cylinder 1 into upper and lower liquid chambers 20 and 21.
The piston 19 is slidably inserted into the piston 19, and the piston 19 has through holes 22, 2 passing through the upper and lower surfaces.
3, and covers one of each of these through holes 22 and 23 to provide a flow resistance to the working fluid that passes through each of these through holes 22 and 23 and flows between the upper and lower liquid chambers 20 and 21. damping force generating means 26 consisting of plate valves 24 and 25 for generating damping force;
27 are provided. A cylindrical stud 28 integrally connects the piston rod 4 and the piston 19, and a shaft hole 29 in the center thereof communicates with the lower liquid chamber 21. Further, two orifices 30 and 31 having a predetermined opening diameter are bored in the cylindrical wall of the stud 28 at a predetermined interval in the axial direction. These orifices 30 and 31 are
As shown in FIG. 3, it communicates with the upper liquid chamber 20 through an annular groove 32 provided on the outer periphery of the cylindrical wall and a communication hole 33 provided in the cylindrical wall of the piston rod 4, respectively.

In the shaft hole 29 of the stud 28, an adjuster 6 is rotatably connected to the final stage drive shaft 8a of the reduction gear 8.
is accommodated. This adjuster 6 is formed with an axial hole 34 that opens toward the lower liquid chamber 21, and as the adjuster 6 swings, each of the orifices 30 and 31 of the stud 28 is opened. Upper and lower communication holes 35 and 36 are formed to selectively match with each other. Furthermore, this adjuster 6
A coil spring 37 is disposed between the stud 28 and the stud 28, and elastically urges the adjuster 6 toward the seal member 38.

Inside the axial hole 34 formed in the adjuster 6, a cylindrical member 39 is provided on its cylindrical wall, and a lower communicating hole among the communication holes 35 and 36 provided in the adjuster 6 is provided. It is inserted and fixed so as to cover only 36. A through hole 40 communicating with the lower communicating hole 36 is provided in the cylindrical wall. A check valve 43 composed of a check spring 41 and a check plate 42 is provided at the upper open end of the cylindrical member 39, and during the extension stroke of the piston rod 4, the open end is During the closed pressure stroke, hydraulic fluid is allowed to flow between the upper and lower liquid chambers 20 and 21 through the communication hole 33, orifice 30, and communication hole 35.

A stop member 44 provided on the outer periphery of the piston rod 4 is for stopping the upward movement of the piston rod 4 by coming into contact with the lower end surface of the guide member 5, and also for stopping the upward movement of the piston rod 4. A lubricating plate 45 interposed therebetween is for smooth rotation of the adjuster 6.

Next, the operation of the hydraulic shock absorber according to the present invention having the above configuration will be explained.

First, when the orifices 30 and 31 of the stud 28 are closed by the regulator 6, when the piston rod 4 with the piston 19 rises inside the cylinder 1, the piston 4 causes the upper liquid chamber 20 to close.
has a high pressure, and conversely, the lower liquid chamber 21 has a low pressure, so the high pressure hydraulic fluid in the upper liquid chamber 20 passes through the through hole 22 that constitutes the damping force generating means 26 provided in the piston 4 and reaches its outlet. The plate valve 24 provided at the end is pushed open to form an orifice, and when passing through the orifice at high speed, the static pressure is changed to dynamic pressure, the pressure drops, and the liquid flows into the lower liquid chamber 21. Thus, the piston 19 is urged downward due to the pressure difference between the upper liquid chamber 20 and the lower liquid chamber 21, and an extension-side damping force is generated that attempts to prevent the extension stroke.

On the other hand, when the piston rod 4 with the piston 19 descends inside the cylinder 1, the piston 19 moves the lower liquid chamber 2
has a high pressure, and conversely, the upper liquid chamber 20 has a low pressure. Therefore, the high-pressure hydraulic fluid in the lower liquid chamber 21 passes through the through hole 23 that constitutes the damping force generating means 27 provided in the piston 19, and reaches its outlet. The plate valve 25 provided at the end is pushed open to form an orifice, and when passing through the orifice at high speed, the static pressure is changed to dynamic pressure, the pressure drops, and the liquid flows into the upper liquid chamber 20. Thus, the piston 19 is urged upward due to the pressure difference between the lower liquid chamber 21 and the upper liquid chamber 20, and a pressure-side damping force is generated that attempts to prevent the pressure stroke.

Next, when the orifices 30 and 31 of the stud 28 match the communication holes 35 and 36 of the regulator 6, when the piston rod 4 moves upward together with the piston 19, the inside of the upper liquid chamber 20 becomes high pressure, and the lower liquid Since the pressure inside the chamber 21 is lower than that, the check plate 42 is moved downward by the spring force of the check spring 41 to close the upper end opening of the cylindrical member 39. Therefore, when the upward movement of the piston rod 4 is slow, all of the hydraulic fluid in the upper liquid chamber 20 flows from the communication hole 33 of the piston rod 4 to the orifice 31, the communication hole 36 of the regulator 6, and the cylindrical member 39.
through the through holes 40 in sequence. Furthermore, as the upward movement of the piston rod 4 becomes faster, the pressure in the upper liquid chamber 20 increases, and eventually a portion of the hydraulic fluid pushes open the damping force generating means 26 provided on the piston 19, causing the lower liquid chamber to open. 21.

On the other hand, when the piston rod 4 moves downward together with the piston 19, the pressure inside the lower liquid chamber 21 becomes high and the pressure inside the upper liquid chamber 20 becomes low compared to that, so that the check plate 42 absorbs the spring force of the check spring 41. The upper open end of the cylindrical member 39 is opened. Therefore, when the downward movement of the piston rod 4 is slow, all of the hydraulic fluid in the lower fluid chamber 21 flows from inside the cylindrical member 39 to the through hole 40, the communicating hole 36, and the orifice 31 formed therein.
a passage passing sequentially through the passage, the communication hole 35 and the orifice 3.
The liquid flows into the upper liquid chamber 20 through two passages that sequentially pass through 0 and further through the communication hole 33. Furthermore, as the downward movement of the piston rod 4 becomes faster, the pressure in the lower end liquid chamber 21 increases, and eventually some of the hydraulic fluid pushes open the damping force generating means 27 provided on the piston 19, causing the upper fluid to flow out. It flows into chamber 20.

As mentioned above, orifice 3 of stud 28
0, 31 are aligned with the communication holes 35, 36 of the regulator 6, a part or all of the hydraulic fluid is transferred to these orifices 30, 36 both when the piston rod 4 moves upwards and downwards. 31 or 31, the amount of hydraulic fluid flowing through the damping force generating means 26, 27 of the piston 19 is reduced or eliminated, the pressure difference between the upper and lower fluid chambers 20, 21 is reduced, and damping is achieved. power can be lowered.

As mentioned above, orifice 3 of stud 28
0 and 31 coincide with the communication holes 35 and 36 of the regulator 6 as the regulator 6 swings, and when they are closed by the regulator 6. The damping force is converted to low damping force or high damping force.

The drive control of the adjuster 6, which swings as described above, will be explained in detail below with reference to FIGS. 1 and 3.

First, when the damping force setter 17 is operated and set to "low", the motor drive circuit 18 sends a drive current to the motor 7 based on the signal from the damping force setter 17, and the motor 7 rotates. As the motor 7 rotates, the final stage drive shaft 8a of the reduction gear 8 and the swinging rod 9 fixed thereto rotate counterclockwise in FIG. The body 14 is compressed, rotational resistance increases, and an overload current flows through the motor 7. This overload current is detected by the motor control unit 16, and a stop signal is sent to the motor drive circuit 18, and the motor 7 is stopped.
The regulator 6 has its communication hole 3 as shown in FIG.
It stops at the position where 5 and 36 coincide with the orifices 30 and 31.

Here, when the counterclockwise rotation of the adjuster 6 is abruptly stopped due to the collision of the swinging rod 9 with the elastic body 14 as described above, the adjuster 6 receives a repulsive force proportional to the collision speed and reverses. Although a force is applied to return the motor in the same direction, the reverse rotational force is suppressed by the combined inshear of the reduction gear 8 and the motor 7. That is, the reverse rotational force is transmitted to the motor 7 by going back through the reduction gear 8, but the motor 7 has a large inshear that is inversely proportional to the gear ratio of the reduction gear 8. Therefore, the combined inshear of the motor 7 and the reduction gear 8 is,
Suppressing the reverse rotational force, that is, the forward and reverse rotational force interferes within the reduction gear 8 to effectively suppress the reverse rotational force,
The separation of the swinging rod 9 from the stopper pin 10 is restricted.

Furthermore, when the motor is stopped, the rotational force in the opposite direction to the swinging rod 9 is transmitted from the elastic body 14 of the stopper pin 10 via the reduction gear 8.
The reverse rotational force is reliably regulated by each gear of the reduction gear 8. Therefore, the adjuster 6 can be reliably held at an appropriate stop position. Therefore, the occurrence of variations in the stop position is sufficiently prevented, and the diameter of the orifice can be set accordingly. Therefore, the degree of freedom in varying the damping force is increased, and it becomes possible to increase the soft damping force in particular.

Further, since the adjuster 6 can be reliably stopped at a predetermined angular position as described above, it is possible to rotate the adjuster 6 at high speed without considering braking of the motor 7. Therefore, the damping force switching time can be shortened, and as a result, an optimal damping force effect can be obtained that immediately responds to the road surface, vehicle running conditions, etc.

Next, when the damping force setter 17 is set to "high", the motor 7 rotates in the opposite direction to that when the damping force setting device 17 is set to "low", and the reduction gear 8 driven by the motor 7 rotates.
The following are rotated clockwise in Fig. 2 and set to "low".
In the same way as in the above case, an overload current flows through the motor 7 in order to urge the elastic body 14 with the swinging rod 9, and the motor control unit 16 detects this and sends a stop signal to the motor drive circuit 18, and the motor 7 stop. At this time,
The orifices 30, 31 are closed by the side walls of the regulator 6. Even if the adjuster 6 is suddenly stopped at the maximum clockwise rotation position,
As described above, reverse rotation is reliably suppressed by the combined inertia of the motor 7 and the reduction gear 8, and when the motor is stopped, the adjustment element 6 is reliably held at the stop position by the reduction gear 8. I can do it. Therefore, effects similar to those described above can be obtained.

In this way, in each embodiment, the adjuster 6 can be stably and reliably stopped at a predetermined rotational position by the stopper mechanism 13, so that variations in the stopping position can be sufficiently prevented.

4 to 6 show other examples of the hydraulic shock absorber according to the present invention.

In this embodiment, a stopper part 10A is provided on the inner periphery of the cylindrical part of the stud 28 provided with the orifice 31 and protrudes in the radial direction, and the stopper part 10A is rotatably inserted into the stud 28. Notch 3 provided in the side wall of adjuster 6
It is scheduled to arrive within 6 days. With this configuration, when the adjuster 6 rotates, both ends of the notch 36 alternately abut against the stopper portion 10A, similarly to the embodiment described above. At this time, the overload current flowing through the motor 7 is detected by the motor control section 16, and thereby a stop signal can be sent to the motor drive circuit 18 to stop the motor 7. Furthermore, by controlling the rotation of the adjuster 6 in this manner, the orifice 31 can be reliably opened and closed to convert the damping force into a low damping force or a high damping force.

Effects of the Invention As is clear from the above explanation, the present invention is provided with a stopper mechanism inside the piston rod for stopping the adjuster at a desired damping force setting position, so it is protected from mud and rain. Of course, the stopper mechanism detects the motor overload current state that occurs when the rotation of the regulator is stopped and brakes the rotation of the motor. This eliminates the need for a detection sensor or brake circuit to detect the rotational angular position of the adjuster, making it possible to simplify the structure for stopping the adjuster at a predetermined damping force setting position. can.

Moreover, since the stopper mechanism is configured to restrict the rotational position of the final output shaft of the reduction gear at a predetermined angular position via the stationary member in the piston rod, the reverse rotational force at the maximum rotational position of the adjuster is applied to the reduction gear. This is effectively suppressed by the combined inertia of the motor and the motor, and the adjuster can be stably and reliably controlled to an appropriate stop position. Furthermore, when the motor is stopped, the adjuster can be reliably held at the stop position by the reduction gear. Therefore, it is possible to sufficiently prevent the occurrence of variations in the stop position, and it is therefore possible to set the diameter of the orifice to be correspondingly large. As a result, the degree of freedom in varying the damping force can be greatly increased, and in particular, the soft damping force can be increased.

Furthermore, since the adjuster can be stopped reliably, it can be rotated at high speed without considering braking of the motor, and therefore the damping force switching time can be shortened. As a result, an optimal damping force action can be obtained that is responsive to the road surface, vehicle running conditions, etc.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway sectional view showing an embodiment of a variable damping force type hydraulic shock absorber according to the present invention, and FIG.
3 is a sectional view taken along the - line in FIG. 1, FIG. 4 is a sectional view showing main parts of another embodiment of the present invention, and FIG. , FIG. 6 is a sectional view showing a state in which the communication hole of the adjuster is closed. 1... Cylinder, 1a... One end, 4... Piston rod, 4... Center hole, 6... Adjuster, 7...
Motor, 8... Reduction gear, 8a... Drive shaft, 12
... Gear case (stationary member), 13 ... Stopper mechanism, 16 ... Motor control section, 19 ... Piston, 20 ... Upper liquid chamber, 21 ... Lower liquid chamber, 2
6, 27... Damping force generating means, 28... Stud (stationary member), 29... Shaft hole, 30, 31... Orifice, 35, 36... Communication hole.

Claims (1)

[Claims] 1. A piston that is slidably inserted into the cylinder to separate the inside of the cylinder filled with hydraulic fluid into two chambers, an upper liquid chamber and a lower liquid chamber, and a piston that is installed in this piston and that a damping force generating means that allows limited displacement flow of hydraulic fluid into a lower fluid chamber; a cylindrical piston rod that extends sealingly through one end of the cylinder and integrally connects with the piston; An adjuster is rotatably housed in the piston rod and opens and closes an orifice that controls the flow rate of the working fluid between the upper liquid chamber and the lower liquid chamber, and a reduction gear in the piston rod is connected to the adjuster. and a motor that rotates the adjuster forward and backward through the motor, and the damping force is controlled by rotating the adjuster with the motor and controlling the opening and closing of the orifice with the adjuster. In the variable damping force hydraulic shock absorber, the damping force obtained by the generating means is adjusted to obtain a desired damping force, and an overload current state of the motor is detected and the circuit of the motor is stopped. A stopper is provided with a motor control section, and restricts the rotational position of the final output shaft of the reduction gear at a predetermined angular position by a stationary member in the piston rod, allowing the adjuster to rotate only within a predetermined angular range. A variable damping force type hydraulic shock absorber, further comprising a mechanism such that the adjuster opens the orifice at at least one end position of the predetermined angle range.