JP3874389B2 - Hydraulic shock absorber for air suspension - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic shock absorber used for automobiles, industrial vehicles, and the like, and more particularly to a damping force variable mechanism suitable for an air suspension hydraulic shock absorber.
[0002]
[Prior art]
The hydraulic shock absorber for air suspension shown in FIG. 4 is a gas spring G having one end coupled to the outer cylinder side of the damper Ao and the other end coupled to the piston rod PR side, and is assembled integrally with the damper Ao. The weight of the vehicle body is supported by the gas spring G, and the vibration of the vehicle is damped by the damper Ao. The air suspension can adjust the vehicle height by changing the gas pressure of the gas spring G when the sprung weight consisting of the weight of the vehicle body and the loaded load changes due to the increase or decrease of the loaded load of passengers or luggage. .
[0003]
At this time, when the gas pressure of the gas spring G is increased, the spring constant also increases. On the other hand, even if the sprung weight and the spring constant change, if the relationship of the generated damping force with respect to the expansion / contraction speed of the damper Ao (hereinafter referred to as damping force-speed characteristic) remains constant, the riding comfort of the vehicle will not exceed the target value. It will be lost. In order to prevent this, it is necessary to change the damping force-speed characteristic according to the gas pressure.
[0004]
The specific change of the damping force-speed characteristic is an damping force adjusting actuator AJ (hereinafter abbreviated as actuator AJ) controlled by the output of the controller based on signals from various sensors arranged at important points of the vehicle body. The rotary valve RV coupled to the lower end of the control rod CR is rotated to open and close a bypass oil passage BP provided in parallel with the piston valve PV.
[0005]
When the bypass oil passage BP is in communication, the soft valve SV is composed of SVe that generates an expansion-side damping force in the soft extension stroke and SVc that generates a compression-side rear damping force in the soft contraction stroke with a small flexural rigidity. (Hereinafter abbreviated as soft valve SV) is selected, and the soft mode for generating a low damping force as shown by S in FIG. 3 is set.
On the contrary, when the bypass oil passage BP is blocked, HVe that generates a large bending stroke and a compression side rear surface damping force that generates a compression side rear damping force of a hard contraction stroke and a large expansion stroke is set. A hard valve HV (hereinafter abbreviated as a hard valve HV) is selected, and a hard mode for generating a high damping force as indicated by H in FIG.
[0006]
Here, the compression-side back damping force of the contraction stroke when the soft valve SV is selected is combined with the compression-side base damping force generated by the base valve BV attached to the lower end of the cylinder CY, and the compression-side damping in the soft mode. It becomes power.
Similarly, the compression-side back damping force in the contraction stroke when the hard valve HV is selected is combined with the base damping force generated by the base valve BV to become the compression-side damping force in the hard mode.
[0007]
As described above, the communication and blocking of the bypass oil passage BP is controlled by the output of the controller based on signals from various sensors arranged at key points of the vehicle body, and the soft mode or the hard mode is automatically set according to the loaded load. This makes it possible to maintain a good ride comfort.
[0008]
[Problems to be solved by the invention]
The actuator AJ in the conventional product is driven as necessary by the controller based on signals from various sensors (not shown), and thus the various sensors and the attached devices such as the controller are necessary.
In addition, in order to change the damping force-speed characteristic, an actuator AJ for selecting the soft valve SV or the hard valve HV is necessary, and there is a problem that the damping force adjusting device becomes greatly complicated. It was.
[0009]
Furthermore, in order to change the damping force-velocity characteristics, a bypass oil passage BP is provided in the piston portion and is opened and closed via the control rod CR. Therefore, a hollow hole is processed in the piston rod PR, and the hollow hole is controlled. There was also a problem that the rod CR and the rotary valve RV had to be mounted.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an air suspension hydraulic shock absorber that simplifies the structure of the damping force adjustment system and the damper of the air suspension. is there.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the means of the present invention comprises a damper and a gas spring, and the damper includes a cylinder, an outer cylinder that accommodates the cylinder, and a reservoir formed between the cylinder and the outer cylinder. A piston that divides the upper oil chamber and the lower oil chamber in the cylinder, a piston rod having one end coupled to the piston and connected to the vehicle body side, and an upper oil chamber and a lower oil chamber formed on the piston. An expansion side port and a pressure side port to be communicated, an extension side hard valve provided at the outlet end of the extension side port so as to be opened and closed, a pressure side hard valve provided at the outlet end of the pressure side port so as to be opened and closed, and the piston rod A bypass passage that bypasses the extension side hard valve and the pressure side hard valve and communicates with the upper oil chamber and the lower oil chamber, and is provided at the outlet end of the upper oil chamber side of the bypass passage so as to be openable and closable. Consists of a soft valve, the gas spring has a gas chamber therein and the other end one end of which is coupled to the outer tube is coupled to the piston rod, soft damping in the soft valve while opening the bypass passage In an air suspension hydraulic shock absorber that generates a force and generates a hard damping force with the extension side hard valve or the pressure side hard valve when the bypass passage is closed, a disk and a piston above the piston are connected to the piston rod. A hollow piston nut to be fastened is coupled , a cap is secured to the lower end portion of the piston nut, the bypass passage is formed in the piston rod, the disk and the piston nut, and the outer periphery of the piston nut and the outer periphery of the cap are formed. The outlet end of the bypass passage is opened through the upper and lower holes on the inner circumference. The fitted freely vertically move the spool, then隔成the gas chamber of the spool side and the outer periphery and the lower hole of the cap, the spool is spring and in the gas spring for biasing in the opening direction the bypass passage The gas chamber is supported in a balanced manner with the gas pressure of the gas chamber on the spool side where the gas is introduced from the gas chamber .
[0011]
In this case, an oil chamber facing the spool-side gas chamber is formed between the spool and the piston nut, and a throttle hole is formed in the middle of the passage connecting the spool-side gas chamber and the gas chamber in the gas spring. In addition, the oil chamber and the bypass passage are communicated with each other via a damping orifice formed in the piston nut or an annular gap formed on the outer surface of the piston nut, thereby reducing the passage area to cope with the pulsation of the pressure of the gas spring during vehicle travel. It is preferable that the pressure of the gas chamber to be leveled is made uniform and the movement of the spool 6 is moderated to stabilize the riding comfort during traveling.
[0012]
Similarly, a gas introduction pipe coaxial with the bypass passage may be inserted into the piston rod and the piston nut, and the gas chamber may be communicated with the gas chamber in the gas spring using the gas introduction pipe.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
The basic structure of the suspension hydraulic shock absorber according to the present invention includes a damper Ao and a gas spring G, as in the conventional example of FIG . The damper A o includes a cylinder 2, an outer cylinder that accommodates the cylinder 2, a reservoir formed between the cylinder 2 and the outer cylinder, and an upper oil chamber A and a lower oil chamber B in the cylinder 2. A partitioning piston 4, a piston rod 1 having one end coupled to the piston 4 and the other end connected to the vehicle body side, an extension port 4C formed on the piston 4 and communicating with the upper oil chamber A and the lower oil chamber B; Pressure side port 4D, extension side hard valve UV e provided at the outlet end of the extension side port 4C so as to be opened and closed , pressure side hard valve UV c provided at the outlet end of the pressure side port 4D so as to be opened and closed, and the piston rod a bypass passage for communicating the the lower oil chamber B the upper oil chamber a to bypass the above extension side hard valve UV e and the compression side hard valve UVc provided 1, the upper oil chamber side outlet end of the bypass passage Open and close It is made from a soft valve LV provided to.
Further, the gas spring G has one end coupled to the outer cylinder and the other end coupled to the piston rod 1 and has a gas chamber Gc therein.
In this suspension hydraulic shock absorber, a soft damping force is generated by the soft valve LV when the bypass passage is open, and a hard hard valve UVe or pressure side hard valve UVc generates a soft damping force when the bypass passage is closed. To generate a strong damping force .
In the present invention, as shown in FIGS. 1 and 2, a disk 3 above the piston 4 and a hollow piston nut 5 for fastening the piston are coupled to the piston rod 1, and the lower end of the piston nut 5 is connected to the piston rod 5. The cap 7 is locked, and the bypass passage is formed in the piston rod 1, the disk, and the 3 piston nut 5.
Further, a spool 6 that opens and closes the outlet end of the bypass passage is fitted to the outer periphery of the piston nut 5 and the outer periphery of the cap 7 through an upper hole 6D and a lower hole 6C on the inner peripheral side so as to be movable up and down. The outer periphery of the cap 7 and the lower hole 6C define a spool-side gas chamber 6A.
As shown in FIG. 2 , the bypass passage includes a communication hole 3B and an annular groove 3A formed in the disk 3, a communication hole 1A and a hollow passage 1B formed in the piston rod 1, and a throttle formed in the piston nut 5. It is comprised by the hole 5B and the through-hole 5A.
Further, a spool 6 for opening and closing a through hole 5A which is an outlet end of the bypass passage is inserted on the outer periphery of the piston nut 5 so as to be movable up and down.
The spool 6 is balanced by the upper spring 8 energizing in the direction of opening the bypass passage and the gas pressure of the lower gas chamber 6A which is opposed to the spring 8 and introduces gas from the gas chamber Gc in the gas spring G. It is supported.
Further, an oil chamber 6B is formed between the spool 6 and the piston nut 5 so as to face the gas chamber 6A, and a throttle hole 5B is formed in the middle of a passage communicating the gas chamber 6A and the gas chamber Gc in the gas spring G. In addition, the oil chamber 6B and the bypass passage are communicated with each other through a damping orifice 5D formed in the piston nut 5 or an annular gap formed in the outer surface of the piston nut 5, thereby reducing the passage area. As a result, the pressure in the gas chamber 6A corresponding to the pulsation of the pressure of the gas spring G during traveling of the vehicle is leveled, and the vertical movement of the spool 6 is moderated to stabilize the riding comfort during traveling. Yes.
One example of connecting the gas chamber 6A to the gas chamber Gc of the gas spring G is as shown in FIG. 2, in which a gas introduction pipe 9 coaxial with the bypass passage BP is inserted into the piston rod 1 and the piston nut 5, and this gas The gas chamber 6 </ b> A is communicated with the gas chamber Gc in the gas spring G using the introduction pipe 9.
This will be described in detail below.
FIG. 2 is a detailed view of the vicinity of the piston valve provided in the piston portion of the damper Ad of the present invention. The left half sectional view shows a soft mode state that generates a low damping force, and the right half sectional view shows a high damping force. Indicates the hard mode state.
[0014]
The disc 3 is assembled above the lower end inlay portion 1E of the piston rod 1, and the disc rear annular window 3C is connected to the piston rod through hole 1A via a disc passage formed by the disc communication hole 3B and the annular groove 3A. Communicating with
A soft valve LV in which the outer peripheral side is supported by the outer frame of the rear annular window 3C, the inner peripheral side is guided by the guide 11, and the inner peripheral rear side is supported by the ring seat 12 is supported by the rear annular window 3C of the disk. Are facing each other.
[0015]
In the soft mode state, the rear annular window 3C of the disk facing the soft valve LV is located below the bypass passage BP including the disk passage, the piston rod passage 1A, the hollow passage 1B, and the piston nut passage 5A. Since it communicates with the chamber B, the outer peripheral side is supported by the outer frame of the rear annular window 3C in the expansion stroke and the inner peripheral side is bent downward, and the inner peripheral side is supported by the ring seat 12 and the outer peripheral side is bent upward in the contraction stroke. Therefore, a low soft mode damping force is generated.
[0016]
An upper surface annular window 4A of the piston 4 communicating with the lower chamber B via the port 4D has a pressure side hard valve UVc that generates a high pressure side rear damping force during the contraction stroke, and a lower surface annular shape communicating with the upper chamber A via the port 4C. A hard valve UV composed of an extension-side hard valve UVe that generates a relatively high extension-side damping force in the extension stroke is opposed to the window 4B across the piston 4, and is assembled below the disk 3. The soft valve LV and the hard valve UV are fastened to the inlay portion 1E at the lower end of the piston rod by a piston nut 5.
[0017]
An upper hole 6D of the spool that opens and closes the through hole 5A is fitted to the outer surface of the piston nut 5, and a lower hole 6C of the spool is fitted to the outer surface of the cap 7 screwed to the lower end portion of the piston nut 5. The spool 6 is guided so as to be movable up and down. The spool 6 is urged in a direction to open the through hole 5A of the piston nut by the spring force of the spring 8.
[0018]
The piston rod 1 has a hollow hole 1C in which a gas pressure introduction tube 9 is disposed. The gas pressure introducing pipe 9 communicates with the gas chamber Gc of the gas spring shown in FIG. 1 through the piston rod through hole 1D and the hollow hole 1C, and the gas pressure of the gas spring G is guided to the gas chamber 5C at the lower end of the piston nut. It is. The gas chamber 5 </ b> C communicates with a gas chamber 6 </ b> A (primary lag pressure chamber) formed on the outer periphery of the lower hole 6 </ b> C of the spool and the cap 7 through a throttle hole 5 </ b> B formed in the piston nut 5.
[0019]
On the other hand, a damping orifice 5D is formed between an oil chamber 6B (first-order lag pressure chamber) formed in the fitting portion on the outer periphery of the spool upper hole 6D and the piston nut 5 and the piston nut through-hole 5A. The through hole 5A communicates with the upper soft valve LV via the bypass passage BP.
[0020]
When the sprung weight is small, the pressure of the gas spring G for maintaining the vehicle height is relatively low, so the spring constant is small. At this time, the damping force-speed characteristic for obtaining the desired riding comfort must be a soft characteristic as indicated by S in FIG. When the pressure of the gas spring G is relatively low, the gas pressure in the gas chamber 6A communicating with the gas spring G by the gas pressure introducing pipe 9 is also low, so that the repulsive force that pushes the spool 6 upward is small, and the spring 8 Can't overcome power.
[0021]
For this reason, the spool 6 remains pressed down, that is, the piston nut through-hole 5A is opened as shown in the left half section of FIG. Since the hydraulic oil in the upper chamber A does not pass through the hard valve UV having a large flexural rigidity but flows through the soft valve LV having a small flexural rigidity and flows into the lower chamber B through the bypass passage BP, the soft oil indicated by S in FIG. It becomes the damping force characteristic of the mode.
[0022]
When the sprung weight made up of the vehicle body weight and the loaded load is large, the gas pressure of the gas spring G is increased in order to maintain the vehicle height, so that the spring constant of the gas spring G also increases. Even if the sprung weight and the spring constant change, if the damping force-speed characteristic of the damper Ad remains constant, the riding comfort of the vehicle deviates from the target value and is impaired. In order to prevent this, it is necessary to change the damping force-speed characteristic according to the gas pressure.
[0023]
A method for changing the damping force-speed characteristic will be described below.
As the pressure of the gas spring G increases, the gas pressure introduced into the gas chamber 5C of the piston nut by the piston rod through hole 1D, the hollow hole 1C, and the gas pressure introducing pipe 9 also increases.
This pressure increases the pressure in the gas chamber 6A through the throttle hole 5B. When the gas pressure is low, the spool 6 is pushed downward by the spring force of the spring 8, but when the gas pressure increases, the repulsive force obtained by multiplying the gas chamber 6 </ b> A by the gas pressure generates the spring force of the spring 8. The spool 6 is moved upward by overcoming the force.
[0024]
As a result, the spool 6 closes the through hole 5A of the piston nut as shown in the right half section of FIG. 2, so that the bypass passage BP between the soft valve LV and the lower chamber B is blocked, and the upper chamber A and the lower chamber B are blocked. Is communicated only via the hard valve UV. Since the bending rigidity of the hard valve UV is set to be larger than the bending rigidity of the soft valve LV, a hard mode damping force characteristic indicated by H in FIG. That is, the damping force can be automatically switched in response to the gas pressure of the gas spring G.
Here, when it is difficult to provide the piston rod through hole 1D due to space in the axial direction, the gas pressure introduction pipe is extended to the upper end of the piston rod and is connected in parallel to the same gas pressure supply source as the gas spring G. You may connect.
[0025]
However, when the pressure of the gas spring G pulsates at a high frequency, such as vibration caused by running on a rough road, the pressure of the gas chamber 5C guided by the gas pressure introduction pipe 9 also pulsates. If the spool 6 moves up and down violently in response to this gas pressure during traveling and the damping force is frequently switched, not only the riding comfort is impaired, but also the steering stability is adversely affected.
In order to prevent this, the space between the gas chamber 5C communicating with the gas spring G and the gas chamber 6A for driving the spool upward is set as the throttle hole 5B, and the pressure in the gas chamber 6A is leveled by the buffering effect of the throttle hole 5B. Thus, it is only necessary to suppress the intense vertical movement of the spool 6.
[0026]
As a result, the damping force-speed characteristic changes correspondingly to the slow pressure fluctuation of the gas spring G when adjusting the vehicle height, but the intense gas spring G such as vibration caused by running on a rough road. It does not change for the pressure fluctuation. For this reason, the ride comfort at the time of driving | running | working can be stabilized.
[0027]
Similarly, when traveling on rough roads, the damper Ad expands and contracts violently, and the pressure in the upper chamber A and the lower chamber B of the cylinder pulsates. In particular, the pressure in the lower chamber B varies greatly between the expansion stroke and the contraction stroke, but this pressure acts as a force for pushing the spool 6 downward through the oil chamber 6B, so the spool 6 moves upward and is in a hard state. There is a fear that the spool 6 is pushed down due to an increase in pressure in the lower chamber B during the contraction stroke, and is switched to a soft state.
[0028]
In order to prevent this, a damping orifice 5D is provided between the oil chamber 6B and the piston nut through-hole 5A, and the vertical movement of the spool 6 is moderated by this damping effect, and is attenuated by the intense expansion and contraction of the damper Ad during vehicle travel. Try not to switch power frequently.
A similar effect can be obtained by providing a predetermined annular gap between the upper hole 6D of the spool and the outer periphery of the piston nut 5 instead of drilling the damping orifice 5D.
[0029]
In the present invention, the gas pressure of the gas spring is introduced into the gas chamber of the spool in the damper, and the spool is moved up and down in response to the pressure, thereby opening and closing the bypass passage between the soft valve and the lower chamber. Since the force is switched between soft and hard, it is possible to sense the pressure of the gas spring by adjusting the vehicle height and automatically obtain the necessary damping force-speed characteristics. For this reason, accessory devices such as various sensors, controllers, and actuators are unnecessary, so that the damping force adjustment system can be simplified and the structure of the suspension hydraulic shock absorber is simplified.
[0030]
【The invention's effect】
As described above in detail , according to the invention of each claim , a spool that opens and closes the outlet end of the bypass passage is inserted into the outer periphery of the piston nut so as to be movable up and down, and the spool is biased in the direction of opening the bypass passage. Since the spring and the gas spring in the gas spring in the gas spring are opposed to the spring and are balanced and supported by the gas pressure, the spool is moved up and down in response to the pressure of the gas spring. The damping force can be switched between soft and hard by opening and closing the bypass passage. As a result , it is possible to sense the pressure of the gas spring by adjusting the vehicle height and automatically obtain the necessary damping force-speed characteristics. For this reason, accessory devices such as various sensors, controllers, and actuators are unnecessary, so that the damping force adjustment system can be simplified and the structure of the suspension hydraulic shock absorber is simplified.
Furthermore, according to the invention of claim 2, an oil chamber facing the gas chamber is formed between the spool and the piston nut, and the throttle hole is formed in the middle of the passage communicating the gas chamber and the gas chamber in the gas spring. The gas spring during vehicle travel is formed by narrowing the passage area by connecting the oil chamber and the bypass passage through a damping orifice formed in the piston nut or an annular gap formed in the outer surface of the piston nut. By leveling the pressure in the gas chamber corresponding to the pulsation of the pressure and making the spool move slowly, the ride comfort during running can be stabilized.
[Brief description of the drawings]
FIG. 1 is an overall view of a hydraulic shock absorber for suspension according to the present invention.
FIG. 2 is an enlarged cross-sectional view of the vicinity of a piston according to a damper Ad of the present invention.
FIG. 3 is an explanatory diagram showing a damping force that changes in response to the pressure of a gas spring.
FIG. 4A is a cross-sectional view of a conventional gas pressure suspension damper Ad.
(B) It is an enlarged view of piston 3 vicinity.
[Explanation of symbols]
A Upper chamber B Lower chamber P Piston R Reservoir G Gas spring Ad Damper LV Soft valve UV Hard valve BP Bypass passage (3B-3A-1A-1B-5A)
DESCRIPTION OF SYMBOLS 1 Piston rod 2 Cylinder 3 Disc 4 Piston 5 Piston nut 5A Through-hole 5B Throttling hole 5D Damping orifice 6 Spool 5D Damping orifice 7 Cap 6A Spool gas chamber 6B Spool oil chamber 6C Spool lower hole 6D Spool upper hole 9 Gas Pressure introduction pipe

Claims (3)

The damper is composed of a damper and a gas spring, and the damper defines a cylinder, an outer cylinder that accommodates the cylinder, a reservoir formed between the cylinder and the outer cylinder, and an upper oil chamber and a lower oil chamber in the cylinder. A piston that has one end coupled to the piston and the other end coupled to the vehicle body side, an extension port and a pressure side port that are formed in the piston and communicate with the upper oil chamber and the lower oil chamber, and the extension port An expansion side hard valve provided at the outlet end of the pressure side, a pressure side hard valve provided at the outlet end of the pressure side port so as to be opened and closed, and an extension side hard valve and a pressure side hard valve provided on the piston rod. A bypass passage that bypasses and communicates the upper oil chamber and the lower oil chamber, and a soft valve that can be freely opened and closed at the outlet end of the upper oil chamber of the bypass passage. There comprising a gas chamber therein and the other end coupled to the outer tube is coupled to the piston rod, to generate a soft damping force in the soft valve while opening the bypass passage, to close the bypass passage in a hydraulic shock absorber for an air suspension makes generating a hard damping force in the extension side hard valve or pressure side hard valve when you are, combine the hollow piston nuts for fastening the upper disk and the piston from the piston to the piston rod, the A cap is secured to the lower end of the piston nut, the bypass passage is formed in the piston rod, the disk, and the piston nut, and an upper hole and a lower hole on the inner peripheral side are respectively formed on the outer periphery of the piston nut and the outer periphery of the cap. Fitting a spool that opens and closes the outlet end of the bypass passage through the And隔成the gas chamber of the spool side and the outer periphery and the lower hole of the cap, the spool of the spool side of introducing the gas from the gas chamber of the spring and in the gas spring for biasing in the opening direction the bypass passage A hydraulic shock absorber for an air suspension, which is supported in balance with the gas pressure in the gas chamber An oil chamber facing the spool-side gas chamber is formed between the spool and the piston nut, and a throttle hole is formed in the middle of a passage communicating the spool-side gas chamber and the gas chamber in the gas spring. A gas chamber corresponding to the pulsation of the pressure of the gas spring when the vehicle travels by communicating the oil chamber and the bypass passage through a damping orifice formed in the piston nut or an annular gap formed in the outer surface of the piston nut. 2. The hydraulic shock absorber for an air suspension according to claim 1, wherein the ride comfort during running is stabilized by leveling the pressure of the vehicle and smoothing the movement of the spool. A gas introduction pipe coaxial with the bypass passage is inserted into the piston rod and the piston nut, and the gas chamber on the spool side is communicated with the gas chamber in the gas spring using the gas introduction pipe. Item 3. The hydraulic shock absorber for air suspension according to Item 1 or 2.

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