JP2016055792A - Vehicle height adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct a detected spring displacement in accordance with a deviation of a detection reference point.SOLUTION: A reference vehicle height storage section 52 prestores a vehicle height at a lowermost position, as a reference vehicle height, which vehicle height censors 40L and 40R appropriately detect at a prescribed reference position. A vehicle height descent control section 53 descends a vehicle body frame 1 to the lowermost position by discharging air from air springs 8L, 8R, 9L, 9R, 10L, 10R, 11L, and 11R. An actual vehicle height acquisition section 54 acquires a vehicle height, as an actual vehicle height, which the vehicle height censors 40L and 40R detect in a state where the vehicle height descent section 53 descends the vehicle body frame 1 to the lowermost position. A vehicle height correction calculation section 55 corrects the vehicle height, based on the reference vehicle height stored by the reference vehicle height storage section 52 and the actual vehicle height acquired by the actual vehicle height acquisition section 54, which the vehicle height sensors 40L and 40R detect after the actual vehicle height acquisition section 54 acquires the actual vehicle height and the vehicle body frame 1 is elevated from the lowermost position.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle height adjusting device in which a vehicle height is adjusted by supplying and discharging fluid to and from a fluid spring interposed between a sprung body and an unsprung body.

  In Patent Document 1, the target distance between the sprung springs is compared with the actual distance between the sprung springs detected by the stroke sensor, and the pressure chamber of the air spring is adjusted so that the actual distance becomes the target distance. A vehicle suspension system for adjusting the amount of air is described.

JP 2008-155761 A

  In the above-described conventional system, there is a possibility that the detection reference point of spring displacement (actual distance) (reference point when detecting the actual distance) is shifted due to deformation or secular change of a part to which the stroke sensor is attached. If the detection reference point of the spring displacement is deviated, the actual spring displacement will deviate from the target distance even if the detected spring displacement (actual distance) matches the target distance.

  Accordingly, an object of the present invention is to provide a vehicle height adjusting device capable of correcting the detected spring displacement according to the deviation of the detection reference point.

  In order to achieve the above object, the present invention is a vehicle height adjustment device in which the vehicle height is adjusted by raising and lowering the spring upper body by supplying and discharging fluid to and from a fluid spring interposed between the spring upper body and the unsprung body. And a spring displacement detection means, a stopper and a stopper receiving portion, a reference spring displacement storage means, a spring body lowering control means, an actual spring displacement acquisition means, and a spring displacement correction means.

  The spring displacement detecting means is attached at a predetermined reference position with respect to the spring upper body or the unsprung body, and detects a displacement of the spring upper body with respect to a predetermined reference height as a spring displacement. The stopper and the stopper receiving portion are provided on one and the other of the spring upper body and the unsprung body, respectively, and come into contact with each other at the lowest position where the spring upper body descends and is closest to the spring lower body, and below the lowest position. Prevents the sprung body from descending.

  The reference spring displacement storage means stores in advance the spring displacement at the lowest position that the spring displacement detection means appropriately detects at the reference position as the reference spring displacement. The sprung body lowering control means discharges the fluid from the fluid spring and lowers the sprung body to the lowest position. The actual spring displacement acquisition means acquires the spring displacement detected by the spring displacement detection means in a state where the spring upper body lowering control means lowers the spring upper body to the lowest position as the actual spring displacement.

  The spring displacement correction means is a reference in which the reference spring displacement storage means stores the spring displacement detected by the spring displacement detection means after the actual spring displacement acquisition means acquires the actual spring displacement and the spring upper body rises from the lowest position. Correction is performed based on the spring displacement and the actual spring displacement acquired by the actual spring displacement acquisition means.

  In the above configuration, the spring displacement at the lowest position that the spring displacement detecting means appropriately detects at the reference position is stored in advance as the reference spring displacement storing means as the reference spring displacement, and the spring upper body lowering control means stores the spring upper body. The actual spring displacement acquisition means acquires the spring displacement actually detected by the spring displacement detection means as the actual spring displacement in the state of being lowered to the lowest position. The spring displacement correction means corrects the spring displacement detected by the spring displacement detection means based on the reference spring displacement and the actual spring displacement.

  Therefore, for example, due to displacement of the spring displacement detecting means from the reference position due to long-term use of the vehicle, deformation of parts of the spring displacement detecting means, etc., the spring displacement detection reference point (spring displacement is detected) Even when the reference point) is deviated, the spring displacement detected by the spring displacement detecting means can be accurately corrected so that an error caused by the deviation of the detection reference point is reduced.

  The spring displacement correction means calculates a difference between the reference spring displacement stored in the reference spring displacement storage means and the actual spring displacement acquired by the actual spring displacement acquisition means as a spring displacement difference, and the spring displacement detected by the spring displacement detection means. May be corrected using the calculated spring displacement difference.

  In the above configuration, the detected spring displacement can be corrected using a previously calculated spring displacement difference, and the correction processing after detecting the spring displacement can be simplified.

  According to the present invention, the detected spring displacement can be accurately corrected according to the deviation of the detection reference point.

1 is an overall view schematically showing an air system including a vehicle height adjusting device according to an embodiment of the present invention. It is a left view which shows typically the rear axle periphery periphery of a vehicle provided with the air system of FIG. It is a right view which shows typically the rear axle periphery periphery of a vehicle provided with the air system of FIG. It is a flowchart which shows a vehicle height correction value calculation process. It is a flowchart which shows a detection vehicle height correction process and an air suspension control process.

  Hereinafter, an embodiment in which the present invention is applied to a track will be described with reference to the drawings. In the following description, the front-rear direction means the front-rear direction of the vehicle, and the left-right direction means the left-right direction when facing the front of the vehicle.

  As shown in FIGS. 1 to 3, the vehicle (truck) includes a body frame (spring body) 1, a cab (not shown), left and right front wheels (not shown), and left and right rear wheels 2L, 2R, 3L, 3R, a front suspension (not shown), a rear suspension 4, and an air system 7 controlled by an ECU (Electric Control Unit) 30.

  The vehicle body frame 1 includes a pair of left and right side frames 5L and 5R extending substantially in parallel along the vehicle front-rear direction, and a plurality of linear cross frames arranged in the vehicle front-rear direction at predetermined intervals and extending in the vehicle width direction. (Not shown). Both ends of each cross frame are coupled to the left and right side frames 5L and 5R. The rear wheels 2L, 2R, 3L, 3R are the left and right rear front wheels 2L, 2R supported by the rear front shaft (rear front axle) 6F, and the left and right rear wheels (rear rear axle) 6R. And rear rear wheels 3L and 3R. Left and right rear front shaft undermembers (underspring bodies) 48L and 48R are connected to the lower portions of the left and right housings 44L and 44R of the rear front shaft 6F, respectively, and the lower portions of the left and right housings 45L and 45R of the rear rear shaft 6R are The left and right rear rear shaft undermembers (unsprung bodies) 49L and 49R are connected to each other. The rear front shaft undermembers 48L and 48R extend forward and rearward of the rear front shaft 6F, and the rear rear shaft undermembers 49L and 49R extend forward and rearward of the rear rear shaft 6R (see FIG. 2).

  The rear suspension 4 is composed of front and rear air springs (fluid springs) 8L, 8R, 9L, 9R, 10L, 10R, 11L, and 11R that expand and contract in the vertical direction by supplying and discharging compressed air (fluid). The rear part of the body frame 1 is supported. The air spring 8L is interposed between the left side frame 5L and the front portion of the left rear front shaft under member 48L, and the air spring 9L is formed of the left side frame 5L and the rear portion of the left rear front shaft under member 48L. The air springs 8L and 9L elastically support the left front side of the rear portion of the vehicle body frame 1 from below so as to be able to move up and down. The air spring 8R is interposed between the right side frame 5R and the front part of the right rear front shaft under member 48R, and the air spring 9R is formed of the right side frame 5R and the rear part of the right rear front shaft under member 48R. The air springs 8R and 9R are elastically supported from below so that the right front side of the rear part of the body frame 1 can be raised and lowered. The air spring 10L is interposed between the left side frame 5L and the front part of the left rear rear shaft under member 49L, and the air spring 11L is formed of the left side frame 5L and the rear part of the left rear rear shaft under member 49L. The air springs 10L and 11L elastically support the rear left side of the rear part of the vehicle body frame 1 from below so as to be able to move up and down. The air spring 10R is interposed between the right side frame 5R and the front portion of the right rear rear shaft under member 49R, and the air spring 11R is formed of the right side frame 5R and the rear portion of the right rear rear shaft under member 49R. The air springs 10R, 11R are elastically supported from below so that the right front side of the rear part of the body frame 1 can be raised and lowered. As described above, the rear portion of the vehicle body frame 1 is elastically supported from below by the air springs 8L, 8R, 9L, 9R, 10L, 10R, 11L, and 11R, and the left side of the vehicle body frame 1 is air by supply and discharge of compressed air. The springs 8L, 9L, 10L, and 11L are raised and lowered, and the right side of the vehicle body frame 1 is raised and lowered by the expansion and contraction of the air springs 8R, 9R, 10R, and 11R by supplying and discharging compressed air. The height is adjusted.

  A compressor (not shown), a main tank 12 that stores compressed air from the compressor, a first relay tank 13, and a second relay tank 14 are provided on the air supply side of the air system 7. The first relay tank 13 is connected in communication with the main tank 12 via the air conduit 15, and the second relay tank 14 is connected in communication with the first relay tank 13 via the air conduit 16. Connected. The first and second relay tanks 13 and 14 store air in a high-pressure state, and supply the stored compressed air to the air consumption side described later. The air line 15 is provided with a safety valve 17 that prevents the internal pressure of the main tank 12 from dropping below a predetermined value. The safety valve 17 stops the supply of compressed air from the main tank 12 to the first and second relay tanks 13 and 14 when the internal pressure of the main tank 12 becomes a predetermined value or less due to some reason during traveling of the vehicle. To do.

  On the air consumption side of the air system 7, the air springs 8L, 8R, 9L, 9R, 10L, 10R, 11L, and 11R, the magnetic valve 18 on the rear front shaft 6F side, and the magnetic on the rear rear shaft side 41 are provided. A valve 19 is provided. The upstream side of the magnetic valve 18 is connected in communication with the first relay tank 13 via the air line 20, and the upstream side of the magnetic valve 19 is connected to the second relay tank via the air line 21. 14 in communication.

  The downstream side of the magnetic valve 18 on the rear front shaft 6F side branches into two paths, and one path (the left front path) is connected to the left front air springs 8L and 9L through the air conduit 22. The other path (the right front side path) is connected to the right front side air springs 8R and 9R through the air conduit 23 in a communicating state. The magnetic valve 18 is connected to the ECU 30 via the signal line 31 and the left front path is selectively switched to the left front air supply state, the left front exhaust state, and the left front air supply / exhaust stop state according to a control signal output from the ECU 30. Instead, the right front side path is selectively switched between the right front air supply state, the right front exhaust state, and the right front air supply / exhaust stop state. In the left front air supply state, compressed air from the first relay tank 13 is supplied to the left front air springs 8L and 9L, and in the left front exhaust state, air is discharged from the air springs 8L and 9L, and the left front air supply and exhaust stop state. Then, supply / exhaust to the air springs 8L, 9L is stopped. Similarly, in the right front air supply state, the compressed air from the first relay tank 13 is supplied to the right front air springs 8R and 9R, and in the right front exhaust state, air is discharged from the air springs 8R and 9R, and the right front air supply. In the exhaust stop state, supply / exhaust to the air springs 8R, 9R is stopped.

  The downstream side of the magnetic valve 19 on the rear rear shaft 6R side also branches into two paths, and one path (left rear path) communicates with the left rear air springs 10L and 11L via the air conduit 24. The other path (right rear side path) is connected to the right rear air springs 10R and 11R through the air pipe 25 in a communicating state. The magnetic valve 19 is connected to the ECU 30 via the signal line 32, and the left rear side path is set to the left rear air supply state, the left rear exhaust state, and the left rear air supply / exhaust stop state in accordance with a control signal output from the ECU 30. The right rear path is selectively switched between a right rear air supply state, a right rear exhaust state, and a right rear air supply / exhaust stop state. In the left rear air supply state, compressed air from the second relay tank 14 is supplied to the left rear air springs 10L and 11L, and in the left rear exhaust state, air is discharged from the air springs 10L and 11L and left rear In the supply / exhaust stop state, supply / exhaust to the air springs 10L, 11L is stopped. Similarly, in the right rear air supply state, compressed air from the second relay tank 14 is supplied to the right rear air springs 10R and 11R, and in the right rear exhaust state, air is discharged from the air springs 10R and 11R. In the right rear supply / exhaust stop state, supply / exhaust to the air springs 10R, 11R is stopped.

  The left front air conduit 22 is provided with a left front pressure sensor 26L for detecting the internal pressure of the air springs 8L, 9L, and the right front air conduit 23 receives the internal pressure of the air springs 8R, 9R. A pressure sensor 26R for detection is provided. Similarly, a pressure sensor 27L for detecting the internal pressure of the air springs 10L, 11L is provided in the left rear air duct 24, and the air springs 10R, 11R of the right rear air duct 25 are provided. A pressure sensor 27R for detecting the internal pressure is provided. The pressure sensors 26L, 26R, 27L, and 27R are connected to the ECU 30 via signal lines 33, 34, 35, and 36, and the internal pressure values detected by the pressure sensors 26L, 26R, 27L, and 27R correspond to the corresponding signals. It is sequentially output to the ECU 30 via the lines 33, 34, 35 and 36.

  A left vehicle height sensor (spring displacement detecting means) 40L is attached to a predetermined reference position of the left side frame 5L, and a right vehicle height sensor (spring displacement detection) is attached to a predetermined reference position of the right side frame 5R. Means) 40R is attached. The left vehicle height sensor 40L detects the displacement (left spring displacement) of the side frame 5L with respect to the rear front shaft 6F (predetermined reference height) as the left vehicle height. The right vehicle height sensor 40R detects the displacement (right spring displacement) of the right side frame 5L with respect to the rear front shaft 6F as the right vehicle height. The left and right vehicle height sensors 40L, 40R are connected to the ECU 30 via signal lines 37, 38, and the left and right detected vehicle height values detected by the vehicle height sensors 40L, 40R are transmitted via the corresponding signal lines 37, 38. It is sequentially output to the ECU 30.

  2 and 3, the left and right vehicle height sensors 40L have a sensor lever 41 and a connecting lever 43 that are rotatably supported, and the side surfaces of the left and right side frames 5L and 5R via the sensor bracket 42. Mounted on each. The upper end portion of the connecting rod 43 is rotatably connected to the tip portion of the sensor lever 41, and the lower end portion of the connecting rod 43 is rotatably supported by the left and right housings 44L and 44R of the rear front shaft 6F. When the vehicle height decreases (the side frame 5L approaches the rear front shaft 6F), the sensor lever 41 tilts upward, and when the vehicle height increases (the side frame 5L moves away from the rear front shaft 6F), the sensor lever 41 moves downward. Tilt to. The vehicle height sensors 40L and 40R output a value (for example, an angle) that varies according to the tilt of the sensor lever 41 to the ECU 30 as a detected vehicle height value. The configuration of the vehicle height sensors 40L and 40R is not limited to the above, and may be, for example, a non-contact type sensor.

  Front left and right stoppers 46L, 46R and rear left and right stoppers are provided on the lower surfaces of the left and right side frames 5L, 5R facing the housings 44L, 44R, 45L, 45R of the rear front shaft 6F and the rear rear shaft 6R. 47L and 47R are fixed respectively. Air is discharged from the air springs 8L, 8R, 9L, 9R, 10L, 10R, 11L, and 11R, and the vehicle body frame 1 is lowered. When the approaching lowermost position is reached, the stoppers 46L, 46R, 47L, 47R come into contact with the upper surfaces (stopper receiving portions) 60L, 60R, 61L, 61R of the housings 44L, 44R, 45L, 45R from above, respectively. Also, the lowering of the side frames 5L and 5R is prevented. The stoppers 46L, 46R, 47L, 47R may be formed of an elastic material, and the stoppers 46L, 46R, 47L, 47R may be provided on the axle side (for example, the housings 44L, 44R, 45L, 45R). Further, the stoppers 46L, 46R, 47L, 47R may not be provided, and the lower surfaces of the side frames 5L, 5R may function as stoppers.

  As shown in FIG. 1, the ECU 30 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), reads an air suspension control processing program stored in the ROM, and performs an air suspension control process. By executing the above, the vehicle height control unit 50 is functioned. Further, the ECU 30 functions as the detected vehicle height correction unit 51 by reading the detected vehicle height correction program stored in the ROM and executing the vehicle height correction value calculation process and the detected vehicle height correction process.

  The RAM functions as a temporary storage area for detection values and CPU calculation results detected by various sensors such as the vehicle height sensors 40L and 40R and the pressure sensors 26L, 26R, 27L, and 27R. In the ROM or RAM, a standard vehicle height and a reference vehicle height (reference spring displacement) described later are stored in advance. The standard vehicle height may be stored as part of the air suspension control processing program, and the reference vehicle height may be stored as part of the vehicle height correction value calculation program.

  The vehicle height control unit 50 starts the air suspension control process in response to the start of the vehicle (power on), and ends the air suspension control process in response to the stop of the vehicle (power off). Further, during the execution of the air suspension control process, the vehicle height control unit 50 performs the air springs 8L, 8R, 9L, 9R, and 10L so that the left and right vehicle heights H of the body frame 1 become the predetermined standard vehicle height Hmid. , 10R, 11L, and 11R are controlled. Specifically, depending on the air pressure detected by the pressure sensors 26L, 26R, 27L, and 27R, the magnetic height H detected by the left and right vehicle height sensors 40L and 40R becomes the standard vehicle height Hmid, respectively. A control signal is output to the valves 18 and 19. By supplying control signals to the magnetic valves 18 and 19, supply and discharge of compressed air to and from the air springs 8L, 8R, 9L, 9R, 10L, 10R, 11L, and 11R are controlled.

  The detected vehicle height correction unit 51 includes a reference vehicle height storage unit (reference spring displacement storage unit) 52, a vehicle height lowering control unit (sprung body lowering control unit) 53, an actual vehicle height acquisition unit (actual spring displacement acquisition unit) 54, and The vehicle height correction calculation unit (spring displacement correction means) 55 is configured. The detected vehicle height correction unit 51 starts the vehicle height correction value calculation process when the vehicle stops (for example, the shift position to the parking position) except for a temporary stop during traveling. Note that a switch or the like that receives an instruction to start the vehicle height correction value calculation process may be provided, and the vehicle height correction value calculation process may be started when the switch receives an input operation of the start instruction while the vehicle is stopped.

The reference vehicle height storage unit 52 is designed so that the left and right vehicle height sensors 40L and 40R appropriately detect the left and right vehicle heights at the reference position in a state where the left and right side frames 5L and 5R have reached the lowest position. previously storing as a reference vehicle height D ₀ of. Reference vehicle height D ₀ is the design information of the vehicle (e.g., vehicle height sensors 40L, descent distance on design from the detection value and the standard vehicle height Hmid the design of the spring displacement of the standard vehicle height Hmid according 40R to the lowermost position Etc.). Incidentally, the vehicle height sensor mounted at the reference position in the production or the like of the vehicle 40L, may be used as a reference vehicle height D ₀ the vehicle height value in the lowermost position 40R is actually detected. The stopper 46L, 46R, 47L, if 47R is formed of an elastic material, the design information for calculating a reference vehicle height _{D 0} includes stopper 46L, 46R, 47L, the elastic modulus of the 47R. Further, in this embodiment, the left and right vehicle height sensors 40L, the value of the reference vehicle height D ₀ of 40R are designed to be equal, the values of the left and right of the reference vehicle height may be different.

Thus, since the reference vehicle height D ₀ is the vehicle height at the lowermost position of the vehicle height sensors 40L, 40R are properly detected at the reference position, the vehicle during manufacturing, the vehicle height sensors 40L, 40R is actually detected vehicle height at the lowermost position (vehicle height) is essentially coincident with the reference vehicle height D _0. However, for example, when the bracket 42 or the like is deformed due to long-term use of the vehicle and the vehicle height sensors 40L and 40R are displaced from the reference position, or components of the vehicle height sensors 40L and 40R (sensor lever 41 and connection lever 43). If the like) is deformed, the actual vehicle height is not coincide with the reference vehicle height D _0.

  In response to the start of the vehicle height correction value calculation process, the vehicle height descent control unit 53 outputs a control signal instructing switching to the exhaust state to the magnetic valves 18 and 19, and the air springs 8L, 8R, and 9L. , 9R, 10L, 10R, 11L, 11R, and the left and right side frames 5L, 5R are lowered to the lowest position.

  The actual vehicle height acquisition unit 54 determines the left and right vehicle heights detected by the vehicle height sensors 40L and 40R when the vehicle height lowering control unit 53 lowers the left and right side frames 5L and 5R to the lowest position. Acquired as (actual spring displacement).

When the actual vehicle height acquisition unit 54 acquires the actual vehicle height, the vehicle height correction calculation unit 55 calculates the difference between the reference vehicle height D ₀ stored in the reference vehicle height storage unit 52 and the actual vehicle height acquired by the actual vehicle height acquisition unit 54. Calculate and store as a height difference (spring displacement difference). In addition, the vehicle height correction calculation unit 55 performs the detected vehicle height correction process during the air suspension control process after the left and right side frames 5L and 5R are lifted from the lowest position. In the detected vehicle height correction process, the vehicle height detected by the vehicle height sensors 40L and 40R is corrected using the calculated vehicle height difference, and the corrected vehicle height is provided to the vehicle height control unit 50. The vehicle height control unit 50 performs the air suspension control process using the vehicle height corrected by the detected vehicle height correction process without directly using the vehicle height detected by the vehicle height sensors 40L and 40R. The vehicle height correction calculation unit 55 may execute the calculation and storage of the vehicle height difference, and the vehicle height control unit 50 may execute the detected vehicle height correction process.

  Next, the vehicle height correction value calculation process executed by the ECU 30 will be described with reference to the flowchart of FIG.

When the vehicle starts the process stops, the current vehicle height detected by the left of the vehicle height sensors 40L (displacement of the left spring) Z _L and right vehicle height current vehicle height sensor 40R detects (right spring displacement) acquires the _{Z R} (step S1), the acquired before 1 handle vehicle height of the left and right left and right vehicle height _Z prv_L, stored as _Z prv_R (step S2).

  Next, a control signal instructing switching to the exhaust state is output to the magnetic valves 18 and 19, and air springs (left spring and right spring) 8L, 8R, 9L, 9R, 10L, 10R, 11L, 11R. Compressed air is discharged from the left and right side frames 5L, 5R (step S3). The compressed air discharge control may be a time control that defines a discharge time, or may be a pressure control that defines a pressure reduction amount.

Next, the current left and right vehicle heights Z _L and Z _R detected by the left and right vehicle height sensors 40L are acquired (step S4), and the left vehicle height Z _{prv_L} one process before stored in step S2 and the current left It is determined whether or not the vehicle height Z _L is equal to the vehicle height Z _L (step S5). If the left vehicle height Z _{prv_L} before one process is equal to the current left vehicle height Z _L, it is stored in step S2. It is determined whether the right vehicle height Z _{prv_R} before one process is equal to the current right vehicle height Z _R (step S6).

When the left vehicle height Z _{prv_L} before one process is different from the current left vehicle height Z _L (step S5: NO), the right vehicle height Z _{prv_R} before one process and the current right vehicle height Z _{When R} is different (step S6: NO), it is determined that the side frames 5L and 5R have not yet reached the lowest position, the process returns to step S2, and the side frames 5L and 5R are further lowered.

The left vehicle height Z _{prv_L} before one process is equal to the current left vehicle height Z _L (step S5: YES), and the right vehicle height Z _{prv_R} before one process and the current right vehicle height Z _R are Are equal (step S6: YES), it is determined that the side frames 5L and 5R have reached the lowest position, and the left and right vehicle height differences Error _L and Error _R are calculated (step S7). Left vehicle height difference Error _L is a reference vehicle height (frame axle contact time of design of the displacement of the left spring) D ₀ from the current left actual vehicle height (left spring frame axle contact time acquired in step S4 Is calculated by subtracting Z _L (Error _L = D ₀ −Z _L ). Similarly, vehicle height difference Error _R on the right, the reference vehicle height (displacement on right spring design time frame axle contact) D ₀ from the current right of actual vehicle height (when frame axle contacted acquired in step S4 It is calculated by the actual displacement) subtracting the _{Z R} of the right spring _{(Error R = D 0 -Z R} ) that.

Finally, the calculated left and right vehicle height differences Error _L and Error _R are stored, and this process is terminated.

  Next, the detected vehicle height correction process and the air suspension control process executed by the ECU 30 will be described with reference to the flowchart of FIG. This process is repeatedly executed every predetermined time.

When the vehicle is started and this process is started, the current vehicle heights Z _L and Z _R detected by the left and right vehicle height sensors 40L are acquired (step S11), and the acquired current vehicle heights Z _L and Z _R are corrected. (Step S12). Specifically, the current vehicle height _Z L, the vehicle height difference calculated in step S7 to _{Z R} Error _L, adds the _{Error R (Z L + Error L} , Z R + Error R), the corrected (vehicle height difference The vehicle height after addition is stored as the current vehicle heights Z _L and Z _R (step S12). Note that the vehicle height used in step S13 and subsequent steps is the corrected vehicle height stored in step S12.

Next, it is determined whether or not the average of the left and right vehicle heights Z _L and Z _R (1/2 (Z _L + Z _R )) is less than the lower limit value Z _lower of the standard vehicle height Hmid (step S13). When the average of the left and right vehicle heights Z _L and Z _R is less than the _lower limit value Z _lower (step S13: YES), it is determined that the body frame 1 is generally low, and an air spring (left spring and right spring) 8L , 8R, 9L, 9R, 10L, 10R, 11L, 11R, the left and right side frames 5L, 5R are raised (step S14), and the process returns to step S11.

When the average of the left and right vehicle heights Z _L and Z _R is equal to or greater than the _lower limit value Z _lower (step S13: NO), the average of the left and right vehicle heights Z _L and Z _R is the upper limit value Z _upper of the standard vehicle height Hmid. It is determined whether or not it exceeds (step S15). If the average of the left and right vehicle heights Z _L and Z _R exceeds the _upper limit value Z _upper (step S15: YES), it is determined that the vehicle body frame 1 is generally high, and an air spring (left spring and right spring) ) The compressed air is discharged from 8L, 8R, 9L, 9R, 10L, 10R, 11L, and 11R, the left and right side frames 5L and 5R are lowered (step S16), and the process returns to step S11.

When the average of the left and right vehicle heights Z _L and Z _R is not less than the _lower limit value Z _lower (step S13: NO) and not more than the _upper limit value Z _upper (step S15: NO), the left and right vehicle heights Z _L and Z _R It is determined whether or not the absolute value of the difference (| Z _L −Z _R |) is less than a predetermined standard vehicle height difference (target value of the lateral difference of displacement) D _LR (step S17). When the absolute value of the difference between the left and right vehicle heights Z _L and Z _R is equal to or greater than the standard vehicle height difference D _LR (step S17: NO), the right vehicle height Z _R is higher than the left vehicle height Z _L. Whether or not (which vehicle height is high) is determined (step S18). If towards the right height _{Z R} is high (step S18: YES), the left air spring (left spring) 8L, 9 L, 10L, increases the left side frame 5L by supplying compressed air to 11L (step S19), if higher in left vehicle height _{Z L} in the opposite: to (step S18 NO), the right air springs (right spring) 8L, 9 L, 10L, and supplies the compressed air to 11L right Side frame 5R is raised (step S20), and the process returns to step 11.

If the absolute value of the difference between the left and right vehicle heights Z _L and Z _R is less than the standard vehicle height difference D _LR (step S17: YES), this process is terminated.

  As described above, according to the present embodiment, the reference vehicle height storage unit 52 determines the design vehicle height at the lowest position (the vehicle height that the vehicle height sensors 40L and 40R appropriately detect at the reference position). The actual vehicle height acquisition unit 54 stores the spring displacement which is stored in advance as the reference vehicle height and is actually detected by the vehicle height sensors 40L and 40R in a state where the vehicle height lowering control unit 53 lowers the vehicle body frame 1 to the lowest position. Get as high. The vehicle height correction calculation unit 55 corrects the vehicle height detected by the vehicle height sensors 40L and 40R based on the reference vehicle height and the actual vehicle height.

  Therefore, for example, due to displacement of the vehicle height sensors 40L, 40R from the reference position due to long-term use of the vehicle, deformation of parts of the vehicle height sensors 40L, 40R (sensor lever 41, connecting lever 43, etc.), etc. Even when the vehicle height detection reference point (reference point for detecting the vehicle height) is deviated, the detected vehicle height is accurately determined so that the error caused by the deviation of the detection reference point is reduced. It can be corrected. For this reason, in the air suspension control process for adjusting the vehicle height to the standard vehicle height, the left and right sides of the body frame 1 can be reliably brought close to the standard vehicle height.

  Further, the vehicle height correction calculation unit 55 corrects the vehicle height detected by the vehicle height sensors 40L and 40R for the air suspension control process using the vehicle height difference calculated in advance in the vehicle height correction value calculation process. Correction processing after detection of height (detected vehicle height correction processing) can be simplified.

  As mentioned above, although the embodiment to which the invention made by the present inventor is applied has been described, the present invention is not limited by the discussion and the drawings that form part of the disclosure of the present invention according to this embodiment. That is, it is needless to say that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on this embodiment are all included in the scope of the present invention.

  For example, in the above-described embodiment, the vehicle height sensors 40L and 40R are attached to the vehicle body frame 1 (spring upper body), but the vehicle height sensors may be attached to the axle side (spring underbody).

  Moreover, although the said embodiment demonstrated the air spring interposed between the vehicle body frame 1 and the member by the side of an axle, two members which interpose an air spring are not limited to the said embodiment, Other two members (For example, a cab and a vehicle body frame) may be used.

  The present invention can be widely applied to a vehicle height adjusting device in which the vehicle height is adjusted by supplying and discharging fluid to and from a fluid spring interposed between the sprung body and the unsprung body.

1 Body frame (spring body)
5L, 5R Side frame 6F Rear front shaft 6R Rear rear shaft 7 Air system 8L, 8R, 9L, 9R, 10L, 10R, 11L, 11R Air spring (fluid spring)
30 ECU
40L, 40R Vehicle height sensor (spring displacement detection means)
44L, 44R, 45L, 45R Housing 46L, 46R, 47L, 47R Stopper 48L, 48R Rear front shaft undermember (Unsprung body)
49L, 49R Rear rear shaft under member (Unsprung body)
50 Vehicle height control unit 51 Detected vehicle height correction unit 52 Reference vehicle height storage unit (reference spring displacement storage means)
53 Vehicle height lowering control part (Spring body lowering control means)
54 Actual vehicle height acquisition unit (actual spring displacement acquisition means)
55 Vehicle height correction calculation unit (spring displacement correction means)
60L, 60R, 61L, 61R Housing top surface (stopper receiving part)

Claims (2)

A vehicle height adjusting device in which the vehicle height is adjusted by raising and lowering the spring upper body by supplying and discharging fluid to and from a fluid spring interposed between the spring upper body and the unsprung body,
A spring displacement detecting means attached to the spring upper body or the unsprung body at a predetermined reference position and detecting a displacement of the spring upper body with respect to a predetermined reference height as a spring displacement;
Provided on one and the other of the spring upper body and the unsprung body, respectively, and the spring upper body descends and abuts each other at the lowest position closest to the spring lower body, and lower than the lowest position. A stopper for preventing the sprung body from descending and a stopper receiving portion;
Reference spring displacement storage means for preliminarily storing the spring displacement at the lowest position that the spring displacement detection means appropriately detects at the reference position as a reference spring displacement;
A spring upper body lowering control means for discharging fluid from the fluid spring and lowering the spring upper body to the lowest position;
Actual spring displacement acquisition means for acquiring, as an actual spring displacement, the spring displacement detected by the spring displacement detection means in a state where the spring upper body lowering control means lowers the spring upper body to the lowest position;
The reference spring displacement storage means stores the spring displacement detected by the spring displacement detection means after the actual spring displacement acquisition means acquires the actual spring displacement and the spring upper body rises from the lowest position. A vehicle height adjusting device comprising: a spring displacement correcting unit configured to correct based on the reference spring displacement and the actual spring displacement acquired by the actual spring displacement acquiring unit. The vehicle height adjusting device according to claim 1,
The spring displacement correction means calculates a difference between a reference spring displacement stored in the reference spring displacement storage means and the actual spring displacement acquired by the actual spring displacement acquisition means as a spring displacement difference, and the spring displacement detection means The vehicle height adjusting device for a vehicle, wherein the spring displacement to be detected is corrected using the calculated spring displacement difference.

Images