JP2015052335A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension device which, even when equipped with a shock absorber in which a gas chamber with a gas enclosed and a liquid chamber with a working liquid filled are divided by a free piston inserted in a cylinder, can reduce the size of a stroke detection device, is easy to mount the stroke detection device and can accurately obtain a stroke of the shock absorber.SOLUTION: A suspension device is equipped with: a shock absorber D having a piston 2 which is held at an end of a piston rod 3 moving in and out of a cylinder 1 with a liquid chamber L formed inside and divides the liquid chamber L into an extension side chamber L1 and a compression side chamber L2, and a free piston 4 which is inserted slidably in a counter-piston rod side of the cylinder 1 and divides the liquid chamber L and a gas chamber G; and a stroke detection device 5 for detecting a stroke of the shock absorber D. The stroke detection device 5 comprises a stroke sensor 50 for detecting an axial displacement of the free piston 4, and stroke computing means 51 for calculating the stroke of the shock absorber D from the detected value.

Description

  The present invention relates to a suspension device.

  In a vehicle, some suspension devices interposed between a vehicle body and a wheel include a stroke detection device that detects a stroke of a shock absorber. The adjustment can be automated and the ride quality can be improved.

  For example, in the suspension device disclosed in Patent Document 1, the shock absorber includes a cylinder filled with hydraulic fluid, a piston rod that enters and exits the cylinder, and a piston rod volume that is externally attached to the cylinder and enters and exits the cylinder. And a free piston that slidably contacts the inner peripheral surface of the sub tank and divides the air chamber in the sub tank. The hydraulic fluid is filled with the gas pressure sealed in the air chamber. Pressurized.

  The stroke detection device disclosed in Patent Document 1 includes a flow meter that detects the flow rate of the working fluid that moves from the cylinder to the sub tank, or a pressure sensor that detects the pressure in the sub tank. Based on the detected value, the stroke of the shock absorber can be obtained by the stroke calculation means. By doing in this way, a stroke detection apparatus can be reduced in size compared with the case where the stroke of a buffer is directly detected with a stroke sensor.

JP 2009-257499 A

  Here, when the sub-tank cannot be externally attached to the cylinder due to the mounting space, such as when the suspension device is a front fork that suspends the front wheel of the motorcycle, the axial length of the cylinder is extended into this cylinder. It is common to insert a free piston.

  However, in this case, if a flow meter is to be mounted, the flow meter must be built in the shock absorber, and the structure becomes complicated, so that it is not feasible.

  On the other hand, the pressure sensor can be mounted without complicating the structure of the shock absorber, but when the stroke of the shock absorber is obtained from the value detected by the pressure sensor, the pressure in the air chamber is detected. Corrections must be made in consideration of the effects of internal temperature and adiabatic expansion and compression of the air chamber. Further, since the air chamber pressure does not change linearly with respect to the stroke of the piston rod, it is difficult to obtain an accurate stroke of the piston rod from the value detected by the pressure sensor, which may be inaccurate. .

  Therefore, an object of the present invention is to reduce the size of the stroke detection device even in the case of including a shock absorber that partitions a gas chamber filled with gas with a free piston inserted into a cylinder and a liquid chamber filled with hydraulic fluid. It is possible to provide a suspension device that can be easily made, can be easily attached to the stroke detection device, and can accurately determine the stroke of the shock absorber.

  Means for solving the above problems include a cylinder in which a liquid chamber filled with a working fluid is formed, a piston rod that enters and exits the cylinder, and a tip of the piston rod that holds the liquid chamber. A shock absorber comprising: a piston partitioned into an extension side chamber and a pressure side chamber; and a free piston which is slidably inserted into the anti-piston rod side in the cylinder and divides the liquid chamber and an air chamber filled with gas. And a stroke detecting device for detecting a stroke of the shock absorber, wherein the stroke detecting device comprises a stroke sensor for detecting an axial displacement of the free piston, and the shock absorber based on the detected value. Stroke calculating means for obtaining the stroke of the stroke.

  According to the suspension device of the present invention, the stroke detection device is provided even in the case of including a shock absorber that partitions a gas chamber filled with gas with a free piston inserted into the cylinder and a liquid chamber filled with hydraulic fluid. While being able to reduce in size, it is easy to attach the stroke detection device, and the stroke of the shock absorber can be obtained accurately.

It is the front view which notched and showed the buffer which concerns on one embodiment of this invention partially.

  A suspension device according to an embodiment of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the suspension device according to the present embodiment includes a cylinder 1 in which a liquid chamber L filled with a working fluid is formed, a piston rod 3 that enters and exits the cylinder 1, and this piston rod. 3, a piston 2 that divides the liquid chamber L into an extension side chamber L1 and a pressure side chamber L2 and is slidably inserted into the anti-piston rod side in the cylinder 1 to hold the liquid chamber L A shock absorber D including a free piston 4 that partitions an air chamber G in which gas is sealed, and a stroke detection device 5 that detects a stroke of the shock absorber D are provided. The stroke detection device 5 includes a stroke sensor 50 that detects the displacement of the free piston 4 in the axial direction, and a stroke calculation means 51 that obtains the stroke of the shock absorber D from the detected value.

  Hereinafter, in detail, the suspension device according to the present embodiment is a front fork that suspends a front wheel of a saddle-ride type vehicle such as a two-wheeled vehicle or a three-wheeled vehicle. Since the structure of the front fork is well known, it is not shown in detail, but a pair of shock absorbers (only one shock absorber D is shown and the other shock absorber is omitted) standing on both sides of the front wheel, A vehicle body side bracket (not shown) that connects the shock absorber D and is connected to a vehicle body frame that is a skeleton of the vehicle body, and a wheel side bracket B that connects the lower end of each shock absorber D to the front axle. The front wheels are supported from both sides by a pair of shock absorbers D. The suspension device may be a front fork that cantilever-supports the front wheels with a single shock absorber D, or a rear suspension that suspends the rear wheels, or a suspension device other than a straddle-type vehicle such as an automobile. There may be.

  In the present embodiment, since the pair of shock absorbers D have a common configuration, only one shock absorber D will be described in detail below. The configuration of the shock absorber D can be changed as appropriate, and one and the other of the pair of shock absorbers D may have different configurations.

  In the present embodiment, the shock absorber D includes a telescopic tube member 9 including a vehicle body side tube 90 and a wheel side tube 91, and the tube member 9 serves as an outer shell of the shock absorber D. The vehicle body side tube 90 is formed with a larger diameter than the wheel side tube 91, a vehicle body side bracket (not shown) is fixed to the outer periphery of the vehicle body side tube 90, and the wheel side bracket B is attached to the lower end portion of the wheel side tube 91. Since it is fixed, when an impact due to road surface unevenness is input, the wheel side tube 91 enters and exits the vehicle body side tube 90 and the shock absorber D strokes. The wheel side tube 91 may be formed to have a larger diameter than the vehicle body side tube 90, and the vehicle body side tube 90 may enter and exit the wheel side tube 91.

  In the tube member 9, the upper side opening of the vehicle body side tube 90 is closed by the cap member C, the lower side opening of the wheel side tube 91 is closed by the wheel side bracket B, and the vehicle body side tube 90 and the wheel side tube 91 overlap. Since the cylindrical gap formed between the portions is held by the inner periphery of the lower end portion of the vehicle body side tube 90 and is closed by an annular seal member 92 that is in sliding contact with the outer peripheral surface of the wheel side tube 91, the tube member 9 is The hydraulic fluid and gas contained inside are sealed so as not to leak outside.

  The shock absorber D includes a cylinder 1 that is held by the cap member C via the cylindrical connecting member 10 and stands on the axial center of the vehicle body side tube 90, and an annular rod that closes the lower opening of the cylinder 1. A guide 6, a piston rod 3 that stands at the bottom of the wheel-side bracket B and is pivotally supported by the rod guide 6 and enters and exits the cylinder 1, and is fixed to the upper end (tip) of the piston rod 3 and slides into the cylinder 1. A piston 2 that is movably inserted, a base rod 8 that stands on the axial center of the cylinder 1 on the side opposite to the piston rod, a base member 7 that is fixed to the lower end of the base rod 8, a base rod 8, and a cylinder 1 and an annular free piston 4 slidably inserted between them.

  In the cylinder 1, a liquid chamber L filled with hydraulic fluid is formed. The liquid chamber L includes an extension side chamber L1 and a pressure side chamber L2 defined by the piston 2, and the pressure side chamber L2 and the base. The liquid reservoir chamber L3 is defined by the member 7. As the hydraulic fluid, oil called hydraulic fluid, or liquid such as water or an aqueous solution is used. The liquid reservoir L3 is partitioned from an air chamber G in which gas is enclosed by a free piston 4. The connecting member 10 that connects the cylinder 1 to the cap member C is formed with a through hole 10a so that gas can freely move in and out of the cylinder 1 through the through hole 10a. In addition, hydraulic fluid is stored outside the cylinder 1 with the tube member 9 (not shown), and the air chamber G is located inside the cylinder 1 from above the liquid level of the hydraulic fluid outside the cylinder 1. Is formed over the free piston 4.

  Gas is sealed in the air chamber G while being compressed, and functions as a suspension spring that elastically supports the vehicle body by always urging the shock absorber D in the extending direction and pressurizing the hydraulic fluid. Since the cap member C is provided with an air valve V that sucks and discharges gas in the air chamber G, the air valve V can adjust the amount of gas in the air chamber G. The air chamber G may be partitioned inside and outside the cylinder 1, the air chamber outside the cylinder 1 may be used for suspension springs, and the air chamber inside the cylinder 1 may be used for pressurizing hydraulic fluid, so that the functions of the air chambers inside and outside the cylinder 1 may be separated. . In this case, it is preferable to provide two air valves so that gas can be separately sucked into and discharged from the inside and outside of the cylinder 1. In the present embodiment, the suspension spring is an air spring, but may be a coil spring.

  Between the piston 2 and the rod guide 6, a balance spring S1 made of a coil spring and an extension spring S2 are provided. The balance spring S1 is formed to be relatively long and can cancel the reaction force of the suspension spring (air chamber G) when the shock absorber D is fully extended. Further, the extending spring S2 is formed to be relatively short, and alleviates the impact when the shock absorber D is fully extended.

  Returning, the piston 2 that divides the expansion side chamber L1 and the compression side chamber L2 is formed with an expansion side piston passage 2a and a compression side piston passage 2b that communicate the expansion side chamber L1 and the compression side chamber L2, and the expansion side piston passage 2a. Allows the flow of hydraulic fluid to move from the expansion side chamber L1 to the compression side chamber L2, and prevents the flow in the opposite direction, and the operation to move the compression side piston passage 2b from the compression side chamber L2 to the expansion side chamber L1. A pressure check valve 21 that allows the flow of the liquid and prevents the flow in the opposite direction is stacked. In the present embodiment, the resistance that the expansion side damping valve 20 gives to the hydraulic fluid that passes through the expansion side piston passage 2a is relatively large, and the resistance that the compression side check valve 21 gives to the hydraulic fluid that passes through the compression side piston passage 2b is compared. Is set to be smaller. However, the specifications of the valve stacked on the piston 2 can be changed as appropriate according to the desired damping force characteristics.

  The base member 7 that partitions the pressure side chamber L2 and the liquid reservoir chamber L3 is formed with an extension side base member passage 7a and a pressure side base member passage 7b that communicate the pressure side chamber L2 and the liquid reservoir chamber L3. An extension check valve 70 that allows the flow of hydraulic fluid to move from the liquid reservoir L3 to the pressure side chamber L2 through the member passage 7a and prevents the flow in the opposite direction, and the pressure side base member passage 7b from the pressure side chamber L2 to the liquid. A compression side damping valve 71 that allows the flow of the hydraulic fluid moving to the reservoir chamber L3 and prevents the flow in the opposite direction is stacked. In the present embodiment, the resistance that the expansion side check valve 70 gives to the hydraulic fluid that passes through the expansion side base member passage 7a is relatively small, and the resistance that the compression side damping valve 71 gives to the hydraulic fluid that passes through the compression side base member passage 7b. Is set to be relatively large. However, the specifications of the valves stacked on the base member 7 can be changed as appropriate according to the desired damping force characteristics.

  The free piston 4 that divides the liquid storage chamber L3 and the air chamber G includes an annular main body 4a, and an annular outer peripheral seal that is attached to the outer periphery of the main body 4a and is in sliding contact with the inner peripheral surface of the cylinder 1. 4b and an annular inner peripheral seal 4c that is attached to the inner periphery of the main body portion 4a and slidably contacts the outer peripheral surface of the base rod 8, and can move between the base member 7 and the cap member C in the axial direction. .

  Subsequently, the stroke of the shock absorber D can be detected by the stroke detection device 5, and the stroke detection device 5 detects the axial displacement of the free piston 4 and the stroke sensor 50. Stroke calculating means 51 for obtaining the stroke of the shock absorber D based on the detected value is provided.

  The stroke sensor 50 includes a cylindrical sensor cylinder 50a that is held by the cap member C, and a sensor rod 50b that is held by the free piston 4 and enters and exits the sensor cylinder 50a, and the displacement of the sensor rod 50b with respect to the sensor cylinder 50a. Is output as an electrical signal. The displacement of the sensor rod 50b is equal to the displacement of the free piston 4 in the axial direction.

  The stroke of the shock absorber D is equal to the displacement of the piston rod 3 with respect to the cylinder 1, the displacement of the piston rod 3 is N, the displacement of the free piston 4 is M, the radial sectional area of the piston rod 3 is X1, and the free piston 4 If the cross-sectional area in the radial direction is X2, N = M × X2 / X1, and the stroke of the shock absorber D can be calculated from the axial displacement M of the free piston 4. In the present embodiment, the stroke calculation means 51 for performing the calculation includes an in-vehicle control unit.

  Next, the operation of the suspension device according to the present embodiment will be described.

  When the wheel side tube 91 retreats from the vehicle body side tube 90 and the piston rod 3 retreats from the cylinder 1 and strokes in the extension direction of the shock absorber D, the hydraulic fluid in the expansion side chamber L1 to be reduced is reduced by the expansion side damping valve 20. And moves to the compression side chamber L2 through the extension side piston passage 2a, so that the shock absorber D generates an extension side damping force due to the resistance of the extension side damping valve 20.

  Further, when the shock absorber D strokes in the extending direction, the piston rod volume (= N × X1) retreated from the cylinder 1 and the volume in the cylinder increase. It opens and moves from the liquid reservoir chamber L3 to the pressure chamber L2 through the extended base member passage 7a. For this reason, the free piston 4 moves downward in FIG. 1, the sensor rod 50b retracts from the sensor cylinder 50a, the stroke sensor 50 detects the displacement M of the free piston 4, and the stroke calculation means 51 detects the detection. From the value (M), the stroke of the shock absorber D is obtained (N = M × X2 / X1).

  On the contrary, when the wheel side tube 91 enters the vehicle body side tube 90 and the piston rod 3 enters the cylinder 1 and the shock absorber D strokes in the compression direction, the hydraulic fluid in the compression side chamber L2 to be reduced is compressed side reverse. The stop valve 21 is opened and moved to the expansion side chamber L1 through the pressure side piston passage 2b.

  Further, when the shock absorber D strokes in the compression direction, the piston rod volume that has entered the cylinder 1 (= N × X1) and the cylinder internal volume decrease, so the hydraulic fluid corresponding to this opens the compression side damping valve 71, It moves from the pressure side chamber L2 to the liquid reservoir chamber L3 through the pressure side base member passage 7b. For this reason, the shock absorber D generates a pressure-side damping force due to the resistance of the pressure-side check valve 21 and the pressure-side damping valve 71. At this time, the free piston 4 moves upward in FIG. 1, the sensor rod 50b enters the sensor cylinder 50a, the stroke sensor 50 detects the displacement M of the free piston 4, and the stroke calculation means 51 is detected. From the value (M), the stroke of the shock absorber D is obtained (N = M × X2 / X1).

  It continues and demonstrates the effect of the suspension apparatus which concerns on this Embodiment.

  In the present embodiment, gas is compressed in the air chamber G while being compressed, and the liquid chamber L is pressurized via the free piston 4 with the gas pressure.

  According to the above configuration, the responsiveness of the generation of the damping force can be improved, and the space between the free piston 4 and the cap member C serves as the air chamber G. Can be used effectively. However, a coil spring may be interposed between the free piston 4 and the cap member C, and the liquid chamber L may be pressurized with this coil spring.

  In the present embodiment, the shock absorber D includes a telescopic tube member 9 including a vehicle body side tube 90 and a wheel side tube 91 and a cap member C that closes the upper opening of the vehicle body side tube 90. Yes. The cylinder 1 is held by the cap member C and stands on the shaft center portion of the vehicle body side tube 90. The stroke sensor 50 includes a cylindrical sensor cylinder 50a that is held by the cap member C, and a sensor rod 50b that is held by the free piston 4 and enters and exits the sensor cylinder 50a. The displacement of the sensor rod 50b is set to be output as an electrical signal.

  According to the above configuration, since the stroke sensor 50 can be arranged on the spring, it is possible to suppress the impact due to road surface unevenness from being transmitted to the stroke sensor 50. In this case, the cylinder 1 is connected to the vehicle body side, and the piston rod 3 is connected to the wheel side, so that the shock absorber D is an inverted type. The shock absorber D may be made upright by being connected to the wheel side. In the present embodiment, the cap cylinder C holds the sensor cylinder 50a and the free piston 4 holds the sensor rod 50b. Conversely, the cap member C holds the sensor rod 50b. The free piston 4 may hold the sensor cylinder 50a. Further, the configuration of the stroke sensor 50 is not limited to the above, and can be changed as appropriate as long as the axial displacement M of the free piston 4 can be detected.

  Further, in the present embodiment, the suspension device includes a cylinder 1 in which a liquid chamber L filled with hydraulic fluid is formed, a piston rod 3 that enters and exits the cylinder 1, and a tip portion of the piston rod 3. The piston 2 that is held and partitions the liquid chamber L into an extension side chamber L1 and a pressure side chamber L2, and is slidably inserted into the anti-piston rod side in the cylinder 1 to enclose the liquid chamber L and gas. A shock absorber D including a free piston 4 that partitions the air chamber G and a stroke detection device 5 that detects a stroke of the shock absorber D are provided. The stroke detection device 5 includes a stroke sensor 50 for detecting the axial displacement M of the free piston 4 and a stroke calculation means 51 for determining the stroke of the shock absorber D from the detected value (M). I have.

  According to the above configuration, the stroke sensor 50 is calculated by calculating the stroke of the shock absorber D from the axial displacement M of the free piston 4 as compared with the case where the stroke of the shock absorber D is directly detected by the stroke sensor 50. It is possible to reduce the size, and as a result, the stroke detection device 5 can be reduced in size.

  Further, according to the above configuration, even if the free piston 4 is the shock absorber D inserted into the cylinder 1, the stroke sensor 50 can be attached using the air chamber G, so that the stroke detector 5 can be easily attached. become.

  Moreover, according to the said structure, even if it is the buffer D which divides the liquid chamber L with which a hydraulic fluid is filled, and the air chamber G with which gas is enclosed with the free piston 4, the displacement of the free piston 4 in the axial direction Since M changes linearly with respect to the stroke of the shock absorber D, an accurate stroke of the shock absorber D can be obtained from the value detected by the stroke sensor 50.

  Although preferred embodiments of the present invention have been described in detail above, it should be understood that modifications, variations and changes may be made without departing from the scope of the claims.

C Cap member D Buffer G Air chamber L Liquid chamber L1 Extension side chamber L2 Pressure side chamber 1 Cylinder 2 Piston 3 Piston rod 4 Free piston 5 Stroke detection device 9 Tube member 50 Stroke sensor 50a Sensor cylinder 50b Sensor rod 51 Stroke calculation means 90 Car body Side tube 91 Wheel side tube

Claims (4)

A cylinder in which a liquid chamber filled with hydraulic fluid is formed, a piston rod that enters and exits the cylinder, and a piston that is held at the tip of the piston rod and divides the liquid chamber into an extension side chamber and a pressure side chamber A shock absorber including a free piston that is slidably inserted on the side opposite to the piston rod in the cylinder and divides the liquid chamber and a gas chamber in which gas is sealed, and detects a stroke of the shock absorber In a suspension device comprising a stroke detection device,
The above-mentioned stroke detection device is provided with a stroke sensor which detects the displacement of the above-mentioned free piston in the direction of an axis, and a stroke calculation means which calculates the stroke of the above-mentioned shock absorber from the detected value. The shock absorber includes a telescopic tube member composed of a vehicle body side tube and a wheel side tube, and a cap member that closes the upper opening of the vehicle body side tube.
The cylinder is held by the cap member and stands up at the axial center of the vehicle body side tube,
The stroke sensor includes a cylindrical sensor cylinder that is held by one of the cap member and the free piston, and a sensor rod that is held by the other of the cap member and the free piston and enters and exits the sensor cylinder. The suspension device according to claim 1, wherein the suspension device is set to output a displacement of the sensor rod with respect to the sensor cylinder as an electric signal.   The suspension according to claim 1 or 2, wherein gas is compressed and sealed in the air chamber, and the liquid chamber is pressurized with the gas pressure through the free piston. apparatus.   X1 is the radial cross-sectional area of the piston rod, X2 is the radial cross-sectional area of the free piston, M is the axial displacement of the free piston, and the stroke of the shock absorber is determined by M × X2 / X1. The suspension device according to any one of claims 1 to 3, characterized by:

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