JP4998936B2 - Spring characteristic variable device in vehicle suspension system - Google Patents

Description

  The present invention relates to a spring characteristic variable device in a suspension system for a vehicle, which makes it possible to obtain a desired characteristic according to the magnitude of an initial load applied to a spring provided to extend a damper.

  Conventionally, the above-described vehicle suspension devices are disclosed in Patent Documents 1 and 2 below. According to these publications, the suspension device includes a hydraulic cylinder type damper having an axial center extending in the vertical direction and mounted on a vehicle body and a wheel suspended on the vehicle body. This damper is capable of extending and contracting in the axial direction, and generates a damping force in accordance with this operation.

  In addition, the suspension device includes a spring that urges the damper to extend, and a hydraulic pressure that is supported by a cylinder tube of the damper and that can push the spring toward the protruding direction of the piston rod. A jack and a hydraulic pump that operates to supply jack oil into the hydraulic jack are provided.

  When an impact force is applied to the wheel from the traveling surface during traveling of the vehicle, the impact force causes the damper to contract while opposing the spring. The damper is extended by the spring when released from the impact force. In this way, the damper repeats expansion and contraction operations. A damping force is generated for each of these operations, whereby the impact force is alleviated and the operability is improved.

  On the other hand, in the “initial state” before the vehicle travels, if the initial load on the spring of the suspension device is large due to the load on the vehicle, etc., the elastic contraction dimension of the spring increases and the vehicle height decreases. It may become too much. In this case, for example, the optical axis of the headlamp may be directed in a direction other than the desired direction.

  In such a case, as a vehicle height adjustment operation, the hydraulic pump is operated, jack oil is supplied into the hydraulic jack, and the spring is moved in the axial direction and the damper by a pusher of the hydraulic jack. The piston rod is pushed toward the protruding direction. Then, the damper is extended and the vehicle height is increased to a desired height. As a result, the riding comfort of the vehicle is improved, for example, the optical axis can be directed in a desired direction.

On the other hand, when the vehicle height is too high in the “initial state”, the hydraulic pump is operated in the opposite direction to discharge jack oil from the hydraulic jack, and the hydraulic jack is driven by a pusher. Retract the spring push. Then, the damper is contracted and the vehicle height is lowered to a desired height. Therefore, also in this case, the ride comfort to the vehicle is improved.
JP 2001-124129 A JP 2005-121060 A

  By the way, when trying to further improve the riding comfort of the vehicle, various characteristics of the spring are selected according to the value of the initial load applied to the spring of the suspension device in the “initial state” before the vehicle travels. It is possible to make it possible.

  However, the spring in each of the above conventional techniques is single, and no consideration is given to the above selection. Therefore, there is still room for improvement in improving the ride comfort.

  The present invention has been made paying attention to the above situation, and an object of the present invention is to provide an initial load applied to a spring for extending the damper of the suspension device in an “initial state” before the vehicle travels. The characteristics of this spring can be easily selected in accordance with the value of, so that an improvement in the riding comfort of the vehicle during traveling can be achieved.

According to the first aspect of the present invention, there is provided a hydraulic cylinder type damper 5 that generates a damping force in accordance with the axial expansion and contraction operations A and B, and the damper 5 that is positioned on the shaft center 2 of the damper 5 to extend the operation A A hydraulic jack 27 including a spring 20 that biases the spring 20, a pusher 32 that can push the spring 20 in the axial direction, and a hydraulic pressure that operates to supply jack oil 29 into the hydraulic jack 27. In the vehicle suspension system including the pump 30,
The spring 20 is movable in the axial direction between the first and second spring members 24 and 25 arranged in the axial direction, and is interposed between the first and second spring members 24 and 25. A spring guide 23 provided,
By actuating the hydraulic pump 30, the pusher 32 of the hydraulic jack 27 moves forward C to push the second spring member 25 via the spring guide 23, and the pusher 32 is moved to the spring guide 23. The spring 20 is based on the hydraulic pressure P of the jack oil 29 when the second spring member 25 is pushed via the hydraulic pump 30 and the discharge oil amount Q of the jack oil 29 discharged by the hydraulic pump 30 (FIG. 2). The shrinkage dimension δ of
Based on the calculated contraction dimension δ of the spring 20, the position of the pusher 32 separated from the spring guide 23 and the pusher 32 when the second spring member 25 is pushed through the spring guide 23. pusher 32 this between a position is determined in steps or steplessly forward movement C should do position, by operating the hydraulic pump 30, to move the pusher 32 to a position above determined It is a thing .

  In this section, the reference numerals appended to the above terms are not to be construed as limiting the technical scope of the present invention to the section “Example” described later or the contents of the drawings.

  The effects of the present invention are as follows.

The invention of claim 1 is a hydraulic cylinder type damper that generates a damping force in accordance with an extension and contraction operation in the axial direction, and a spring that is positioned on the axis of the damper and urges the damper to extend. In a vehicle suspension system comprising: a hydraulic jack provided with a pushing body capable of pushing the spring in the axial direction; and a hydraulic pump that operates to supply jack oil into the hydraulic jack.
A first and second spring member arranged in the axial direction; and a spring guide that is movable in the axial direction and interposed between the first and second spring members. Prepared,
By actuating the hydraulic pump, the pusher of the hydraulic jack moves forward and pushes the second spring member through the spring guide, and the pusher moves the second spring member through the spring guide. Based on the hydraulic pressure of the jack oil at the time of pushing and the discharge oil amount of the jack oil discharged by the hydraulic pump, the contraction dimension of the spring is calculated,
Based on the shrinkage dimensions of springs calculated above, this between a position of the pusher when pressing the second spring member through the position and the spring guide of the pusher remote from the spring guide The position where the pusher should move forward is determined stepwise or steplessly, and the hydraulic pump is operated to move the pusher to the determined position.

For this reason, the pusher is moved to a position to be moved forward based on the contraction dimensions of the first and second spring members of the spring in the “initial state” before the vehicle travels . In this state, if the first and second spring members of the spring are contracted by a load applied from the outside during the subsequent travel, and the spring guide of the spring is pressed against the pusher, then The second spring member of the spring performs a contraction operation, but the contraction operation of the first spring member of the spring is restricted. That is, the spring constant of the spring changes before and after the press contact. Thereby, various characteristics according to each moving position of the above-mentioned pusher are obtained in this spring.

Here, the contraction dimensions of the first and second spring members of the spring in the “initial state” of the vehicle are proportional to the initial load applied to the spring. For this reason, in the “initial state” of the vehicle, the value of the initial load applied to the first and second spring members of the spring for extending the damper of the suspension device and the contraction operation as described above are performed during the subsequent travel. Depending on the characteristics of the first spring member to be regulated and the characteristics of the second spring member that performs the contracting operation , various characteristics of this spring can be easily selected, thereby improving the riding comfort of the vehicle during traveling. Achieved.

In addition, as described above, the spring is movable between the first and second spring members arranged in the axial direction and the first and second spring members. And a spring guide that can be pushed by the pusher.

  For this reason, each spring constant of the 1st, 2nd spring member with which the said spring is provided can be defined separately. Therefore, the degree of freedom in obtaining various characteristics of the spring can be improved, and the riding comfort of the vehicle during traveling can be further improved.

  The present invention relates to a spring characteristic variable device in a suspension device for a vehicle according to the present invention, in the “initial state” before the vehicle travels, depending on the value of the initial load applied to the spring for extending the damper of the suspension device. In order to achieve the object of making it possible to easily select various types of vehicles and thereby improving the riding comfort of the vehicle during traveling, the best mode for carrying out the present invention is as follows. That's right.

  That is, the vehicle suspension system includes a hydraulic cylinder damper that generates a damping force in accordance with an axial expansion and contraction operation, and a spring that is positioned on the axial center of the damper and biases the damper to extend. And a hydraulic jack provided with a pushing body capable of pushing the spring in the axial direction, and a hydraulic pump for supplying jack oil into the hydraulic jack.

The spring includes first and second spring members arranged in the axial direction, and a spring guide that is movable in the axial direction and interposed between the first and second spring members. I have.

By actuating the hydraulic pump, the pusher of the hydraulic jack moves forward and pushes the second spring member through the spring guide, and the pusher moves the second spring member through the spring guide. The contraction dimension of the spring is calculated based on the hydraulic pressure of the jack oil at the time of pushing and the amount of jack oil discharged from the hydraulic pump.

Based on the shrinkage dimensions of springs calculated above, this between a position of the pusher when pressing the second spring member through the position and the spring guide of the pusher remote from the spring guide The position where the pusher should move forward is determined stepwise or steplessly, and the hydraulic pump is operated to move the pusher to the determined position.

  In order to describe the present invention in more detail, an embodiment thereof will be described with reference to the attached FIGS. 1-5.

  In FIG. 1, reference numeral 1 denotes a vehicle suspension device. This suspension device 1 has a hydraulic cylinder in which an axis 2 extends in the vertical direction, an upper end is pivotally supported on the vehicle body side by an upper pivot support 3, and a lower end is pivoted on a wheel side by a lower pivot support 4. A damper 5 of the type is provided.

  The damper 5 includes a cylinder tube 7, a cap cover 8 that closes the upper end opening of the cylinder tube 7, a head cover 9 that closes the lower end opening of the cylinder tube 7, and is slidable in the cylinder tube 7 in the axial direction. The piston 12 is inserted into the cylinder tube 7 to divide the inside of the cylinder tube 7 into first and second oil chambers 10 and 11, and extends from the piston 12 on the shaft 2, and the head cover 9 is slid in the axial direction. A piston rod 13 is provided so as to penetrate the hydraulic oil 14 and the hydraulic oil 14 filled in the first and second oil chambers 10 and 11 is provided.

  The cap cover 8 is pivotally supported by the upper pivot 3 on the vehicle body side, and the protruding end of the piston rod 13 is pivotally supported by the lower pivot 4 on the wheel side. The piston 12 is formed with an orifice 15 that allows the first and second oil chambers 10 and 11 to communicate with each other.

  The damper 5 generates a damping force when the hydraulic oil 14 in the second oil chamber 11 flows through the orifice 15 toward the first oil chamber 10 in accordance with the extension operation A in the axial direction. Further, the damper 5 generates a damping force by the hydraulic oil 14 in the first oil chamber 10 flowing through the orifice 15 toward the second oil chamber 11 in accordance with the contraction operation B in the axial direction.

  Spring seats 18 and 19 are attached to the upper end of the cylinder tube 7 and the protruding end of the piston rod 13, respectively. Located on the shaft center 2 of the damper 5, a coil-shaped spring 20 is interposed between the spring seats 18 and 19 and is fitted on the damper 5. The spring 20 is interposed between the spring seats 18 and 19 in an elastically compressed state. As a result, the spring 20 urges the spring seats 18 and 19 to move away from each other, that is, urges the damper 5 to extend.

  The spring 20 is located between the spring seats 18 and 19 in the axial direction of the damper 5, and is an annular spring guide 23 that is externally fitted to the cylinder tube 7 so as to be slidable in the axial direction. First and second spring members 24 and 25 are provided between the spring seats 18 and 19 and the spring guide 23, respectively. The first and second spring members 24 and 25 are provided separately from each other, and the spring constants are the first and second spring constants k1 and k2. In this case, k1 = k2 may be sufficient and the values may be different from each other. The overall spring constant k of the first and second spring members 24, 25, that is, the spring constant k of the spring 20 is k1 · k2 / (k1 + k2).

  Further, the suspension device 1 is supported by the cylinder tube 7, and a hydraulic jack 27 that enables the spring 20 to be pushed in the protruding direction (downward) of the piston rod 13, and the hydraulic jack 27 is directed into the hydraulic jack 27. A hydraulic pump 30 is provided that operates to supply the jack oil 29 through the oil passage 28 and enables the hydraulic jack 27 to operate.

  The hydraulic jack 27 is placed on the shaft center 2 so as to be fitted on the cylinder tube 7, and is fitted between the cylinder tubes 7 and 31 so as to be slidable in the axial direction. And a pusher 32 that is an annular piston. Specifically, the other cylinder tube 31 is formed integrally with the spring seat 18. The pusher 32 can be moved back and forth C and D toward the spring guide 23 which is a midway portion of the spring 20 in the longitudinal direction. A sealed space surrounded by the cylinder tubes 7 and 31 and the pusher 32 is a jack oil chamber 33.

  The hydraulic pump 30 is supported by the pump case 36 so as to be capable of forward and reverse rotations E and F around a cylinder-shaped pump case 36 having both ends opened in the axial direction and an axis 37 of the pump case 36. A bolt-shaped pump shaft 38, a piston 39 that is fitted so as to be slidable in the axial direction with respect to the pump case 36, and screwed to the pump shaft 38, and is supported on the pump case 36 side. And an actuator 40 that is a DC motor that enables the pump shaft 38 to be driven in the forward and reverse rotations E and F.

  A sealed space surrounded by one end of the pump case 36 and the piston 39 is a pump oil chamber 41. The jack oil chamber 33 in the hydraulic jack 27 and the pump oil chamber 41 in the hydraulic pump 30 are connected to each other by the oil passage 28. The oil passage 28, the jack oil chamber 33, and the pump oil chamber 41 are filled with jack oil 29.

  When the pump shaft 38 is rotated forward E by driving the actuator 40, the pump oil chamber 41 is contracted by the piston 39 interlocked with the pump shaft 38. Then, the jack oil 29 in the pump oil chamber 41 is pressurized, and the pusher 32 of the hydraulic jack 27 is moved forward C toward the spring guide 23 by the jack oil 29. On the other hand, when the pump shaft 38 is rotated in the reverse direction F, the pump oil chamber 41 is expanded by the piston 39 interlocked with the pump shaft 38. Then, the jack oil 29 is sucked into the pump oil chamber 41, whereby the pusher 32 of the hydraulic jack 27 is moved backward D so as to separate from the spring guide 23.

  A pump rotation speed sensor 44 that detects the rotation speed of the hydraulic pump 30 in conjunction with the pump shaft 38, a pressure sensor 45 that detects the hydraulic pressure of the jack oil 29, the pump rotation speed sensor 44, and the pressure sensor 45 And a control device 46 that electronically controls the damper 5 and the spring 20.

  Each of the left half views of the damper 5 and the spring 20 in FIG. 1 shows the “predetermined initial state” before the vehicle travels, such as when the vehicle is in an unloaded state. In this case, the damper 5 is extended by the spring 20 and the piston 12 is brought into contact with the head cover 9 to prevent further extension A. That is, the damper 5 is in the maximum extended state. In this case, the initial separation dimension in the axial direction between the spring guide 23 and the pusher 32 is indicated by L in the drawing.

  Each of the right half views of the damper 5 and the spring 20 in FIG. 1 shows an “initial state” before traveling of the vehicle in which the initial load W is applied to the spring 20 due to the vehicle being loaded. In this case, the spring guide 23 and the pusher 32 are separated from each other in the axial direction, and the spring 20 is not pushed by the hydraulic jack 27.

  When an impact force is applied to the wheels from the traveling surface during traveling of the vehicle, the damper 5 is contracted by the impact force B against the spring 20. The damper 5 is extended by the spring 20 when released from the impact force. In this way, the damper 5 repeats the expansion and contraction operations A and B. A damping force is generated for each of these operations A and B, whereby the impact force is alleviated and the operability is improved.

  In FIG. 2, by the operation of the hydraulic jack 27, the pushing body 32 of the hydraulic jack 27 comes into contact with the spring guide 23 which is a middle part in the longitudinal direction of the spring 20 and starts to push the spring guide 23. Indicates the state.

  FIG. 3 shows a flowchart of the control of the suspension device 1 by the control device 46, in which S1-S8 show the steps of the program.

  For convenience of explanation, as shown in the left half of the damper 5 and the spring 20 in FIG. 1, when the vehicle is in a “predetermined initial state”, the spring 20 is not given an external force and is elastic. The following explanation will be made assuming that no general contraction has occurred.

  As shown in the right half of the damper 5 and the spring 20 in FIG. 1, the spring 20 is adjusted to a desired characteristic in the “initial state” of the vehicle when an initial load W is applied to the spring 20. The adjustment work to be performed is performed as follows under the control of the control device 46.

  In FIG. 3, from the “initial state” of the vehicle, first, the actuator 40 of the hydraulic pump 30 is operated (S2), and the pump shaft 38 is rotated forward E. Then, the jack oil 29 in the pump oil chamber 41 passes through the oil passage 28 and is supplied to the jack oil chamber 33 of the hydraulic jack 27. Then, the pusher 32 is moved forward C by the jack oil 29 until it abuts against the spring guide 23 (FIG. 2). At this time, the dimension of the forward movement C of the pusher 32 of the hydraulic jack 27, that is, the stroke S of the hydraulic jack 27 is S1 (see FIG. 1). Further, during the forward movement C in which the pusher 32 reaches the stroke S1, the hydraulic pressure P of the jack oil 29 in the hydraulic jack 27 is kept at a constant low hydraulic pressure P1 (FIG. 4).

  After the pushing body 32 comes into contact with the spring guide 23, the hydraulic pressure P of the jack oil 29 in the jack oil chamber 33 starts to rise, and the pushing body 32 causes the spring guide 23 to move in the protruding direction of the piston rod 13. It starts to be pushed toward ((S1, P1) in FIGS. 2 and 4).

  At this time, the start of increasing the hydraulic pressure P detected by the pressure sensor 45 is input to the control device 46. Then, it is determined that the spring guide 23 of the spring 20 has started to be pushed by the pusher 32 of the hydraulic jack 27 due to the start of the rise of the hydraulic pressure P (S3). Then, the total discharge oil amount Q of the jack oil 29 of the hydraulic pump 30 is detected from the start of the operation of the hydraulic pump 30 until the spring guide 23 of the spring 20 starts to be pushed by the pusher 32 (S4). ). Specifically, in the control device 46, the product of the rotational speed of the pump shaft 38 of the hydraulic pump 30 detected by the pump rotational speed sensor 44 and the discharge amount of the hydraulic pump 30 at each rotational speed is calculated as described above. A discharge oil amount Q is calculated (detected).

  Next, the contraction dimension δ from the free length of the spring 20 due to the initial load W is calculated based on the discharge oil amount Q (S5). Specifically, since the stroke S1 of the hydraulic jack 27 = the discharge oil amount Q / the cross-sectional area of the jack oil chamber 33, first, the stroke S1 is calculated based on the discharge oil amount Q.

  Further, since the first contraction dimension δ1 of the first spring member 24 = the initial separation dimension L−the stroke S1, the first contraction dimension δ1 is calculated. Further, since the initial load W = the first contraction dimension δ1 × the first spring constant k1, the initial load W is calculated. Further, since the second contraction dimension δ2 of the second spring member 25 = initial load W / second spring constant k2, the second contraction dimension δ2 of the second spring member 25 is also calculated. Since the contraction dimension δ of the spring 20 is equal to the first contraction dimension δ1 + the second contraction dimension δ2, the contraction dimension δ of the spring 20 due to the initial load W is calculated as described above (S5).

  In FIG. 5, the spring 20 exhibits a plurality of first to fourth characteristics, and according to each of the contraction dimension δ of the spring 20 and the initial load W with respect to the spring 20 among these characteristics. The characteristics are automatically selected under the control of the control device 46.

  The first to fourth characteristics are obtained by operating the hydraulic pump 30 to cause the pusher 32 of the hydraulic jack 27 to move forward C by a desired dimension and stop at that position. Specifically, the position where the pusher 32 should move forward C corresponding to the respective values of the contraction dimension δ and the initial load W of the spring 20, that is, predetermined strokes S1-S3, S0 of the hydraulic jack 27. Are stored in the control device 46 in advance. The strokes S1-S3 and S0 of the hydraulic jack 27 have a relationship of S1> S2> S3> S0, and the larger the contraction dimension δ and the initial load W, the larger the value of the stroke S. The strokes S1-S3 and S0 may be set infinitely.

  In FIG. 3, based on the contraction dimension δ and initial load W of the spring 20 detected by the execution of S1-S5 and the data, the position where the pusher 32 of the hydraulic jack 27 should move forward C, that is, the hydraulic jack. 27 predetermined strokes S are determined (S6). Next, the pusher 32 of the hydraulic jack 27 is moved forward C by the operation of the hydraulic pump 30. When the pusher 32 is moved forward C by the stroke S determined as described above, the pusher 32 is stopped by stopping the hydraulic pump 30 (S7).

  1, 2 and 5, when the stroke S of the hydraulic jack 27 is S1, the pusher 32 is in contact with the spring guide 23 as shown in FIG. For this reason, when the vehicle is running, when the impact force (load) is applied to the wheels from the running surface, and the damper 5 and the spring 20 are contracted B, the spring guide 23 is always the pusher 32. The first characteristic that the contraction operation B of the first spring member 24 of the spring 20 is restricted, that is, only the second spring member 25 having the second spring constant k2 acts on the spring 20. Demonstrate.

  On the other hand, when the stroke S of the hydraulic jack 27 is S2, S3, or S0, the spring 20 exhibits the second to fourth characteristics. That is, when an impact force (load) is applied to the wheel as described above and the damper 5 and the spring 20 are contracted B, initially, the spring guide 23 and the pusher 32 of the hydraulic jack 27 are different from each other. It is separated. Therefore, the first and second spring members 24 and 25 of the spring 20 act together, and the spring constant is k. Next, if the contraction operation B proceeds and the spring guide 23 comes into pressure contact with the pusher 32, then the contraction operation B of the first spring member 24 of the spring 20 is restricted. That is, after the press contact, only the second spring member 25 having the second spring constant k2 acts.

  Therefore, in the “initial state” of the vehicle, the characteristics of the spring 20 depend on the contraction dimension δ of the spring 20 and the initial load W applied to the spring 20 that extends the damper 5 of the suspension device 1. Various selections are made automatically and easily, so that the ride comfort of the vehicle during traveling can be improved.

  As described above, the spring 20 is movable in the axial direction with the first and second spring members 24 and 25 arranged in the axial direction, and the first and second spring members 24 are arranged in the axial direction. , 25 and a spring guide 23 interposed between them, and the pusher 32 can be pushed by the spring guide 23.

  For this reason, each spring constant of the 1st, 2nd spring members 24 and 25 with which the above-mentioned spring 20 is provided can be defined individually. Therefore, the degree of freedom in obtaining various characteristics of the spring 20 can be improved, and the riding comfort of the vehicle during traveling can be further improved.

The above is due to the illustrated example, the discharge oil amount Q jack oil 29 by the upper SL hydraulic pump 30 may be calculated as the product of duration and the discharge amount per unit time, the discharge oil amount Q May be detected directly by a flow meter.

It is a partial longitudinal cross-sectional view of a suspension apparatus. FIG. 2 is a partial enlarged cross-sectional action explanatory diagram of FIG. 1. It is a flowchart figure of control by a control apparatus. It is a graph which shows the relationship between the stroke of a hydraulic jack, and the hydraulic pressure in a hydraulic jack. It is a figure which shows each characteristic of a spring.

DESCRIPTION OF SYMBOLS 1 Suspension apparatus 2 Axis center 5 Damper 7 Cylinder tube 13 Piston rod 14 Hydraulic oil 20 Spring 23 Spring guide 24 1st spring member 25 2nd spring member 27 Hydraulic jack 28 Oil path 29 Jack oil 30 Hydraulic pump 31 Other cylinder tubes 32 Pusher 33 Jack oil chamber 44 Pump speed sensor 45 Pressure sensor 46 Control device A Extension operation B Contraction operation C Forward movement D Reverse movement E Forward rotation F Reverse rotation k Spring constant k1 First spring constant k2 Second spring constant P Hydraulic pressure L Initial separation dimension Q Discharged oil amount S Stroke W Initial load δ Shrinkage dimension δ1 First shrinkage dimension δ2 Second shrinkage dimension

Claims (1)

A hydraulic cylinder type damper that generates a damping force in accordance with the expansion and contraction operations in the axial direction, a spring that is positioned on the axial center of the damper and urges the damper to extend, and moves toward the axial direction. In a vehicle suspension system including a hydraulic jack having a pusher that can push a spring, and a hydraulic pump that operates to supply jack oil into the hydraulic jack,
A first and second spring member arranged in the axial direction; and a spring guide that is movable in the axial direction and interposed between the first and second spring members. Prepared,
By actuating the hydraulic pump, the pusher of the hydraulic jack moves forward and pushes the second spring member through the spring guide, and the pusher moves the second spring member through the spring guide. Based on the hydraulic pressure of the jack oil at the time of pushing and the discharge oil amount of the jack oil discharged by the hydraulic pump, the contraction dimension of the spring is calculated,
Based on the shrinkage dimensions of springs calculated above, this between a position of the pusher when pressing the second spring member through the position and the spring guide of the pusher remote from the spring guide In a suspension system for a vehicle, wherein a position where the pusher should move forward is determined stepwise or steplessly, and the hydraulic pump is operated to move the pusher to the determined position. Spring characteristic variable device .

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