JP2007290592A - Tire air-pressure control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire air-pressure control apparatus that estimates whether an air pump as a pressurizing means performs an appropriate adiabatic compression of air to appropriately generate pressurized air. <P>SOLUTION: The tire air-pressure control apparatus includes: a pressure sensor S1 for detecting an air pressure of a tire air chamber Rb; an air-pressure generating device A including the air pump for generating pressurized air by performing the adiabatic compression of the air, and supplying the pressurized air generated by the air pump to the tire air chamber Rb; a control valve device V for controlling the on/off operation of supplying the pressurized air to the tire air chamber Rb; and an electric control device ECU. The electric control device ECU includes: a timer means for measuring an elapsed time when the supply of the pressurized air from the air pump to the tire air chamber Rb is stopped; a calculating means for calculating a reduced amount of the air pressure of the tire air chamber Rb during a predetermined time period when the elapsed time; and a determining means for determining whether the reduced amount of the air pressure is above a specified value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tire air pressure control device configured so that the air pressure of a tire air chamber in a vehicle wheel is maintained within a set range.

One type of tire pressure control device of this type includes a pressure means for adiabatically compressing the atmosphere to generate pressurized air, and a pressure that can supply the pressure air generated by the pressure means to the tire air chamber of the wheel. A generating device, a pressure sensor for detecting the air pressure of the tire air chamber, and when the air pressure drops to a lower limit set value, the pressurized air is supplied from the pressurizing means to the tire air chamber, and the stop condition is satisfied. For example, the following Patent Document 1 discloses a control device that stops supply of pressurized air from the pressurizing means to the tire air chamber.
Japanese Patent Laid-Open No. 7-25214

  In the tire air pressure control device described in Patent Document 1 described above, the operation of the air pressure generating device including the pressurizing means (air compressor) is controlled by the control device, and the air pressure of the tire air chamber is lower than the control device. When the pressure is reduced to the set value (target pressure), the pressurized air is supplied from the pressurizing means to the tire air chamber, and when the stop condition is satisfied (a predetermined time has elapsed since the start of the supply of pressurized air by the pressurizing means) The supply of pressurized air from the pressurizing means to the tire air chamber is stopped. For this reason, it is possible to supply the pressurized air generated by the pressurizing means to the tire air chamber of the wheel from when the tire air chamber pressure decreases to the lower limit set value until the stop condition is satisfied. is there.

  However, in the tire pressure control device described in Patent Document 1 described above, after the condition for stopping the supply of pressurized air from the pressurizing means to the tire air chamber is satisfied, the adiabatic compression function ( It is impossible to estimate whether the pressurizing function is good or bad, and it is impossible to estimate whether the pressurizing means accurately generates the compressed air by adiabatically compressing the atmosphere.

  The present invention has been made to cope with the above-described problems, and includes a pressurizing unit that adiabatically compresses the atmosphere to generate compressed air, and the compressed air generated by the pressurizing unit is used as a tire air chamber of a wheel. An air pressure generating device that can be supplied to the pressure sensor, a pressure sensor that detects the air pressure of the tire air chamber, and when the air pressure drops to a lower limit set value, the pressurized air is supplied from the pressurizing means to the tire air chamber, Tire pressure control comprising a control device for stopping the supply of pressurized air from the pressurizing means to the tire air chamber when a stop condition is satisfied, wherein the air pressure is maintained within a set range In the apparatus, the time measuring means for measuring the elapsed time from when the supply of the pressurized air from the pressurizing means to the tire air chamber is stopped, and the predetermined time when the elapsed time becomes the predetermined time Calculating means for calculating the amount of reduction in the serial air pressure, it is characterized in that the air pressure reduction amount is provided a judging means for judging whether equal to or greater than a prescribed value.

  In this tire pressure control device, if the air is accurately adiabatically compressed by the pressurizing means and the compressed air is accurately generated (that is, if the adiabatic compression function of the pressurizing means is normal), the pressure is added. The temperature of the compressed air is higher by a predetermined amount than the temperature of the atmosphere, and the air pressure in the tire air chamber is accordingly increased accordingly. For this reason, when there is no air leakage in the pneumatic circuit including the tire air chamber, when the elapsed time reaches a predetermined time, the temperature of the pressurized air in the tire air chamber during the predetermined time is the atmospheric temperature (general The air pressure of the tire air chamber is correspondingly reduced with the temperature difference, and the air pressure reduction amount described above ( The amount of decrease in air pressure in the tire air chamber during a predetermined time) is equal to or greater than a specified value.

  On the other hand, when the atmosphere is not properly adiabatically compressed by the pressurizing means (that is, when the adiabatic compression function of the pressurizing means is abnormal), the temperature of the pressurized air generated by the pressurizing means However, the temperature difference does not increase as in the case described above, and the temperature difference between the pressure air in the tire air chamber and the air temperature does not increase as in the case described above. For this reason, in this case, the air pressure reduction amount does not exceed a specified value.

  Therefore, after the condition for stopping the supply of the pressurized air from the pressurizing means to the tire air chamber is satisfied, it is determined by the determining means that the air pressure reduction amount is equal to or greater than the specified value, whereby the pressurizing means It can be estimated that the adiabatic compression function is normal, and it can be estimated that the adiabatic compression function of the pressurizing means is not normal by determining that the air pressure reduction amount is not equal to or greater than the specified value. As a result, after the condition for stopping the supply of pressurized air from the pressurizing means to the tire air chamber is satisfied, the quality (normal / abnormal) of the adiabatic compression function of the pressurizing means can be estimated and added. It can be estimated whether or not the pressure means accurately generates compressed air by adiabatically compressing the atmosphere.

  In carrying out the present invention, it is possible to provide notifying means for notifying the determination result by the determining means. In this case, it is possible to notify the occupant of the quality (normal / abnormal) of the adiabatic compression function of the pressurizing means by the notifying means. In the implementation of the present invention, when the stop condition is satisfied, the air pressure may rise to an upper limit set value, and supply of pressurized air from the pressurizing means to the tire air chamber It may be when the time reaches the set time.

  In carrying out the present invention, the pressurizing means may be an air pump that is driven as the wheels rotate. In this case, when the vehicle travels over the unevenness of the road surface to determine whether the adiabatic compression function of the air pump is good (normal or abnormal) from the detected value of the pressure sensor while the vehicle is stopped. It is possible to prevent misjudgment caused by the tire pressure change that occurs.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a tire pressure control device according to the present invention. This tire pressure control device can supply pressurized air to a tire air chamber Rb of a wheel B via a control valve device V. A, a pressure sensor S1 that detects the air pressure (P) of the tire air chamber Rb, and a control valve device V that controls the operation of the air pressure generating device A, and the air pressure (P) of the tire air chamber Rb is within a set range. It is configured to be maintained within the range of the lower limit set value P1 to the upper limit set value P2. As shown in FIG. 2, the tire air chamber Rb is formed by the wheel B1 of the wheel B and the tire B2, and a pressure sensor S1 for detecting the air pressure (P) of the tire air chamber Rb is provided therein. Yes.

  As shown in detail in FIGS. 2 and 3, the air pressure generating device A and the control valve device V are assembled to the axle hub 11 that rotates together with the wheels B, and are driven at the vehicle inner end of the axle hub 11. The axle 12 is spline-fitted and connected so that torque can be transmitted. The connection between the axle hub 11 and the drive axle 12 is fixed by a lock nut 13.

  The air pressure generating device A includes an air pump 20 (sometimes referred to as an air compressor) as pressurizing means for generating compressed air by adiabatically compressing the atmosphere. The control valve device V includes a pressure control valve 30 and an adjustment device 40, and also includes a relief valve 50 disposed coaxially inside the pressure control valve 30, and the shaft portion (rotation) of the axle hub 11 together with the air pump 20. Axis 11a is arranged coaxially.

  The air pump 20 is disposed on the innermost side of the vehicle among the air pump 20, the pressure control valve 30 and the adjustment device 40. The pressure control valve 30 is disposed between the air pump 20 and the adjusting device 40. The adjustment device 40 is disposed on the outermost side of the vehicle among the air pump 20, the pressure control valve 30 and the adjustment device 40.

  The air pump 20 is configured to be driven with the rotation of the wheel B and to be stopped with the rotation of the wheel B. The tire of the wheel B is passed through the pressure control valve 30 based on the rotation of the wheel B. A cam member that can supply pressurized air to the air chamber Rb, includes a non-rotatable cylindrical member 21, a rotatable cylinder 22 formed on the shaft portion 11a of the axle hub 11, and a piston 23 as a reciprocating member. 24 and a pair of cam followers 25.

  The cylindrical member 21 is non-rotatably supported by a support member (not shown), and a cylinder 22 is disposed in the inside of the wheel B via a pair of bearings Br1 and Br2 and a pair of annular seal members 26 and 27. It is supported in a liquid-tight manner so as to be rotatable around the center of rotation. The pair of bearings Br1 and Br2 are disposed apart from each other by a predetermined amount in the axial direction, and are interposed between the cylindrical member 21 and the cylinder 22 so as to sandwich the cam member 24 in the axial direction. Can be rotated. The pair of annular seal members 26 and 27 are disposed apart from each other by a predetermined amount in the axial direction, and are interposed between the cylindrical member 21 and the cylinder 22 so as to sandwich the cam member 24 and both bearings Br1 and Br2 in the axial direction. In addition, the space between the cylindrical member 21 and the cylinder 22 is liquid-tightly sealed.

  The cylinder 22 includes a cylinder main body 22A and a cylinder head 22B screwed to the outer end of the cylinder main body 22A so as to be airtight and detachable. The cylinder body 22A is formed integrally with the shaft portion 11a of the axle hub 11, and has a pair of axial long holes 22a and a cylinder inner hole 22b extending in the cylinder axial direction. The cylinder head 22B is a bottomed cylindrical plug member that is airtightly and detachably assembled to the axle hub 11. The cylinder head 22B includes a suction / discharge passage 22c and a discharge passage 22d, and includes a pressure guide passage 22e and a suction passage 22f. Have.

  The pair of axially elongated holes 22a are guide means for guiding the piston 23 and each cam follower 25 so as to be able to rotate integrally with the cylinder 22 and reciprocate in the axial direction of the piston, and are spaced 180 degrees apart in the circumferential direction of the cylinder 22. Is formed. The cylinder inner hole 22b accommodates the piston 23, and the outer end of the vehicle is closed by the cylinder head 22B. The cylinder head 22B and the piston 23 form a pump chamber Ro.

  The suction / discharge passage 22c is always in communication with a communication passage 31a provided in the valve body 31 of the pressure control valve 30, and is a suction check valve Vi (an annular seal member having a V-shaped cross section) assembled to the cylinder head 22B. It is possible to introduce air into the pump chamber Ro through the discharge check valve Vo (configured with an annular seal member having a V-shaped cross section) assembled to the valve body 31 of the pressure control valve 30. The air can be led out from the pump chamber Ro.

  The discharge passage 22d is a passage for guiding the pressurized air discharged to the air chamber Ra1 through the discharge check valve Vo to the discharge passage 11b provided in the axle hub 11, and includes a radial communication hole 22d1 provided in the cylinder head 22B, It is constituted by a communication groove 22d2 provided on the outer periphery of the cylinder head 22B. The discharge passage 11b provided in the axle hub 11 communicates with the tire air chamber Rb through the communication passage Ba provided in the wheel B as shown in FIG.

  The pressure guide passage 22e is a communication hole in the cylinder radial direction provided in the cylinder head 22B, and the pressurized air in the discharge passage 22d is formed in the air chamber Ra2 formed between the valve body 31 and the stopper 32 of the pressure control valve 30. Can be introduced. The suction passage 22f is always in communication with the atmosphere communication passage 31b provided in the valve body 31 of the pressure control valve 30, and can be communicated / blocked with respect to the communication passage 31a provided in the valve body 31 of the pressure control valve 30. . Note that the atmosphere communication passage 31b provided in the valve body 31 is always in communication with the atmosphere through the atmosphere communication passage 42b formed in the adjustment screw 42 of the adjustment device 40.

  The piston 23 is inserted into a cylinder inner hole 22b of the cylinder 22 via a pair of annular seal members 28, 29, and is assembled so as to be able to rotate integrally with the cylinder 22 and to reciprocate in the piston axial direction. . The piston 23 has an annular groove 23a and a through hole 23b extending in the piston radial direction. The pair of annular seal members 28 and 29 are disposed apart from each other by a predetermined amount in the axial direction, and are interposed between the piston 23 and the cylinder 22 at the axial end portion of the piston 23, and between the piston 23 and the cylinder 22. Is hermetically and liquid tightly sealed.

  The annular groove 23 a is formed on the outer periphery of the piston 23 between the pair of annular seal members 28 and 29, and forms an annular space R 1 between the cylinders 22. The annular space R <b> 1 communicates with an annular space R <b> 2 formed between the pair of annular seal members 26 and 27 through the axial long holes 22 a of the cylinder 22. Each annular space R1, R2 has a volume that does not change even if the piston 23 reciprocates in the piston axial direction, and is sealed by four seal members 26, 27, 28, 29. The annular spaces R1, R2 and the like are oil chambers for storing a required amount of lubricating oil. The oil chambers contain bearings Br1, Br2, a cam member 24, a cam follower 25, a compression coil spring Sp, and the like. ing.

  The cam member 24 is constituted by a pair of cam sleeves 24A and 24B connected in the piston axial direction, and is provided integrally with the cylindrical member 21 (not axially movable and non-rotatable). Are arranged coaxially. The cam member 24 has an annular cam portion 24a that varies in the axial direction. The cam portion 24a is a cam groove, and a ball 25c of each cam follower 25 is engaged therewith. The cam portion 24a has a cam surface that receives a load in the piston axial direction (a load in the horizontal direction in the drawing) and a load in the piston radial direction (a load in the vertical direction in the drawing) from the ball 25c of each cam follower 25. Has a V-shaped cross section, and is formed in an even number of cycles (for example, two cycles) in the circumferential direction of the cylinder 22.

  Each cam follower 25 is constituted by a shaft 25a divided into two in the piston 23, and a roller 25b and a ball 25c assembled to each of the shafts 25a, and the piston 25 is inserted into the through hole 23b of the piston 23 by the shaft 25a. 23 is movably provided in the radial direction. Each cam follower 25 is engaged with a cam portion (cam groove) 24a of the cam member 24 by an end portion extending in the piston radial direction, that is, a ball 25c, and rotates relative to the cam member 24. This moves in the direction of the piston axis.

  Each shaft 25a is a load transmission element assembled to the through hole 23b of the piston 23 so as to be movable in the radial direction of the piston 23 (the axial direction of the through hole 23b), and a compression coil spring Sp interposed therein. Is urged outward of the diameter of the piston 23. Each shaft 25a is a support that rotatably supports the roller 25b, and rotatably supports the roller 25b at a small-diameter end protruding from the through hole 23b of the piston 23.

  Each roller 25b is rotatably fitted in the axial long hole 22a of the cylinder 22 in a state where the roller 25b is rotatably fitted to the small diameter end portion of the shaft 25a, and the cam follower 25 moves in the cylinder axial direction. It is possible to roll along the axial long hole 22a of the cylinder 22. Each roller 25b has a hemispherical concave receiving portion at the outer end, and supports the ball 25c so that it can roll.

  Each ball 25c is a convex portion of the cam follower 25 that is supported by the roller 25b so as to be able to roll and engages with a cam portion (cam groove) 24a of the cam member 24 so as to roll. The shaft 25a and the roller 25b are In response to the elastic force of the compression coil spring Sp, it is elastically engaged with the cam portion (cam groove) 24a of the cam member 24 without any gap.

  The compression coil spring Sp is a pressing means that presses the ball 25c of each cam follower 25 toward the cam portion (cam groove) 24a of the cam member 24 in the radial direction of the piston 23, and is provided on the shaft 25a of each cam follower 25. It is assembled in a state where a predetermined preliminary load is applied to the bottomed mounting hole.

  In the air pump 20, when the cylinder 22 (axle hub 11) rotates with the valve body 31 of the pressure control valve 30 held at the illustrated position, the piston 23 and the cam follower 25 rotate integrally with the cylinder 22. Thus, it rotates relative to the cam member 24 and moves in the axial direction. Therefore, the rotational movement of the cylinder 22 can be converted into the reciprocating motion of the piston 23, and the volume of the pump chamber Ro can be increased / decreased by the reciprocating motion of the piston 23, and the suction check valve Vi, the communication passage 31a, Air can be sucked into the pump chamber Ro through the suction / discharge passage 22c, and air can be discharged from the pump chamber Ro through the suction / discharge passage 22c, the communication passage 31a, and the discharge check valve Vo.

  The pressure control valve 30 is assembled in the cylinder head 22B, and includes a valve body 31 and a stopper 32. The pressure control valve 30 is engaged with the valve body 31 via a spring retainer 33. A compression coil spring 34 whose position can be controlled and whose urging force to the valve body 31 can be adjusted by the adjusting device 40 is provided. The pressure control valve 30 is activated when the air pressure (P) of the tire air chamber Rb is lowered to the lower limit set value P1 (the valve body 31 is moved from the illustrated position against the urging force of the compression coil springs 34 and 52). It is possible to supply the pressurized air from the pump chamber Ro to the tire air chamber Rb from the pump chamber Ro to the tire air chamber Rb, and the pressure of the pressurized air supplied from the pump chamber Ro to the tire air chamber Rb is the upper limit. When the set value P2 increases (P1 <P2), the state is switched from the illustrated state to the operating state, and the supply of pressurized air from the pump chamber Ro to the tire air chamber Rb can be limited (stopped).

  The valve body 31 is assembled in the cylinder head 22B so as to be airtight and movable in the cylinder axial direction via a discharge check valve Vo and an annular seal member 35 assembled on the outer periphery. An air chamber Ra1 communicating with the discharge passage 22d is formed therebetween, and an air chamber Ra2 communicating with the stopper 32 through the pressure guide passage 22e is formed between the air passage Ra1 and the stopper 32. The stopper 32 is assembled with an annular seal member 36 on the inner periphery and an annular seal member 37 on the outer periphery, and is hermetically interposed between the cylinder head 22B and the valve body 31. The outer periphery of the vehicle is integrally screwed to the cylinder head 22B at the outer end of the vehicle.

  In the pressure control valve 30, the valve body 31 is held at the illustrated position when the air pressure (P) of the tire air chamber Rb decreases from the lower limit set value P1 to the upper limit set value P2. The communication between the communication passage 31a and the suction passage 22f is blocked by the suction check valve Vi. Therefore, the suction check valve Vi allows the air flow from the atmosphere to the pump chamber Ro, and the discharge check valve Vo allows the air flow from the pump chamber Ro to the tire air chamber Rb (the state shown in the drawing). The check valve Vi blocks communication between the communication passage 31a and the suction passage 22f to restrict the air flow from the pump chamber Ro to the atmosphere, and the discharge check valve Vo controls the air flow from the tire air chamber Rb to the pump chamber Ro. regulate. Therefore, in this state (ON state of the pressure control valve 30), the air is sucked into the pump chamber Ro by the reciprocating motion of the piston 23 accompanying the rotation of the wheel B, and the pressurized air is transferred from the pump chamber Ro to the tire air chamber. Discharged toward Rb.

  Further, in this pressure control valve 30, when the air pressure (P) of the tire air chamber Rb rises to the upper limit set value P2 and decreases to the lower limit set value P1, the valve body 31 is compressed by the compression coil spring 34, 52 is moved in the axial direction by a predetermined amount from the illustrated position against the urging force of 52, and the communication passage 31a communicates with the suction passage 22f regardless of the suction check valve Vi. For this reason, the suction check valve Vi has lost its function (backflow prevention function), the communication passage 31a communicates with the suction passage 22f to allow the air flow between the pump chamber Ro and the atmosphere, and the discharge check valve. Vo regulates the air flow between the discharge passage 22d and the communication passage 31a, that is, between the pump chamber Ro and the tire air chamber Rb. When the valve body 31 is moved by a predetermined amount from the illustrated position against the urging force of the compression coil springs 34 and 52 (operating state), the stepped portion of the valve body 31 is attached to the inner periphery of the stopper 32. This is in contact with the seal member 36. Therefore, in this state (OFF state of the pressure control valve 30), even if the piston 23 reciprocates as the wheel B rotates, the air sucked into the pump chamber Ro is pushed back toward the atmosphere, and the pump chamber There is no discharge from Ro toward the tire air chamber Rb.

  The adjusting device 40 can adjust the position of the spring support 41 that supports the other end of the compression coil spring 34 in the pressure control valve 30 (the fixed end that does not move when the valve body 31 moves), and the position of the spring support 41. An adjustment screw 42 is provided. The spring support 41 is a movable part at the time of adjustment of the stroke sensor S2 for detecting the ON / OFF state of the pressure control valve 30 and detecting the movement amount of the adjustment screw 42. The adjustment screw is adjusted by the hemispherical convex part 41a. 42 is rotatably engaged.

  The adjustment screw 42 is configured separately from the spring support 41, and has a male screw portion 42a and an atmosphere communication path 42b. The male screw portion 42a can advance and retract to the female screw portion 22g of the cylinder head 22B. It is screwed on. The adjusting screw 42 also serves as a cap and can be rotated from the outside of the vehicle. A hexagonal head 42c for detachably attaching an adjusting tool (not shown) that can be manually operated to the outer end. Is formed. A filter 43 is attached to the atmosphere communication path 42b.

  The relief valve 50 is pressurized when the pressure of the pressurized air supplied from the pump chamber Ro to the tire air chamber Rb, that is, the air pressure (P) in the air chamber Ra1, is equal to or higher than the relief set value P3 higher than the upper limit set value P2. It is for releasing air to the atmosphere, and is engaged with a valve body 51 capable of opening / closing a relief passage 31c provided in the valve body 31 at one end (movable side end). And a compression coil spring 52 that defines the movement timing of the valve body 51 (the opening timing of the relief passage 31c).

  The valve body 51 is assembled in the valve body 31 of the pressure control valve 30 so as to be movable in the cylinder axial direction, and is almost resistant to the rod portion 45 of the stroke sensor S2 (the movable portion during adjustment of the stroke sensor S2). And a rod portion relatively movable in the cylinder axis direction). The compression coil spring 52 is engaged with the spring support 44 integrated with the above-described spring support 41 at the other end portion (fixed side end portion), and the urging force acting on the valve body 51 can be adjusted by the adjusting device 40. It is. At the time of adjustment by the adjusting device 40, the urging force of the compression coil spring 34 acting on the valve body 31 of the pressure control valve 30 is also adjusted at the same time, and the above-described upper limit set value P2 and relief set value P3 can be adjusted simultaneously.

  In the relief valve 50, a relief passage 31 c provided in the valve body 31 of the pressure control valve 30 can be communicated with or shut off from the air chamber Ra 1 by an annular seal member 38 assembled to the valve body 31. Therefore, the valve element 31 of the pressure control valve 30 moves in the cylinder axial direction against the urging force of the compression coil springs 34 and 52, and the air chamber Ra1 and the relief passage 31c communicate with each other through the seal member 38. Only in this state, the pressure in the air chamber Ra1 is applied to the relief passage 31c so that the relief valve 50 can be operated.

  By the way, in this embodiment, as shown in FIG. 1, the output of the pressure sensor S1 (electric signal indicating the air pressure (P) of the tire air chamber Rb) and the output of the stroke sensor S2 (ON of the pressure control valve 30). An electric signal indicating an OFF state and an electric signal indicating the amount of movement of the adjusting screw 42) are input to the electric control unit ECU wirelessly. In addition, an instrument panel display ID that can display “normal adiabatic compression function” and “abnormal adiabatic compression function” is electrically connected to the electric control unit ECU.

  The electric control unit ECU includes a microcomputer that executes a program corresponding to the flowchart of FIG. 4 based on the outputs of the pressure sensor S1 and the stroke sensor S2, and supplies pressurized air from the air pump 20 to the tire air chamber Rb. Counting the elapsed time (t) from when supply stops (when the pressure control valve 30 changes from the ON state to the OFF state), and the predetermined time when the elapsed time (t) reaches the predetermined time ta Calculating the air pressure decrease amount (Pd) of the tire air chamber Rb in the interior, determining whether the air pressure decrease amount (Pd) is equal to or greater than the specified value Pa, and displaying the determination result on the instrument panel display unit ID It is possible.

  In this embodiment configured as described above, when the pressure control valve 30 is changed from the ON state to the OFF state during use of the vehicle (from a state where pressurized air can be supplied toward the tire air chamber Rb). When the supply becomes impossible), the microcomputer of the electric control unit ECU starts executing the program corresponding to the flowchart of FIG. 4 based on the output of the stroke sensor S2, and in step 101, the output of the pressure sensor S1. (P) is read and stored as the pressure (Po) when stopping pressurization.

  The microcomputer of the electric control unit ECU starts a timer in step 102 and repeatedly executes step 103 until the elapsed time (t) reaches a predetermined time ta. Further, when the elapsed time (t) reaches the predetermined time ta, the output (P) of the pressure sensor S1 is read in step 104, and the air pressure decrease amount (Pd) from the pressure (Po) at the stop of pressurization stored in step 101. = Po-P).

  Further, the microcomputer of the electric control unit ECU determines whether or not the air pressure decrease amount (Pd) is not less than a specified value Pa in step 105, and executes step 106 if it is not less than the specified value Pa. Execution of the program is terminated, and if it is not the specified value Pa or more, step 107 is executed to terminate the execution of the program. In step 106, display of “normal adiabatic compression function” is instructed, and “normal adiabatic compression function” is displayed on the instrument panel display section ID. In step 107, the display of “abnormal adiabatic compression function” is instructed, and “abnormal adiabatic compression function” is displayed on the instrument panel display ID.

  In short, in this embodiment, if the air is accurately adiabatically compressed by the air pump 20 and the compressed air is accurately generated (that is, if the adiabatic compression function of the air pump 20 is normal), The temperature of the pressurized air is higher by a predetermined amount than the atmospheric temperature, and the air pressure in the tire air chamber Rb is accordingly increased accordingly. For this reason, when there is no air leakage in the pneumatic circuit including the tire air chamber Rb, when the elapsed time (t) reaches the predetermined time ta, the temperature of the pressurized air in the tire air chamber Rb during the predetermined time ta Decreases in accordance with a temperature difference from the atmospheric temperature (generally, an outside air temperature that hardly changes during a predetermined time ta), and the air pressure (P) of the tire air chamber Rb is also corresponding to this temperature decrease. The air pressure decrease amount (Pd) is not less than the specified value Pa.

  Note that no air leakage occurs in the pneumatic circuit including the tire air chamber Rb, for example, that the output (P) of the pressure sensor S1 hardly decreases when the vehicle is stopped, or the pressure control valve 30 is in the OFF state. It can be easily detected because the output (P) of the pressure sensor S1 hardly changes.

  On the other hand, when the atmosphere is not accurately adiabatic compressed by the air pump 20 (that is, when the adiabatic compression function of the air pump 20 is abnormal), the temperature of the pressurized air generated by the air pump 20 However, the temperature difference between the pressurized air in the tire air chamber Rb and the atmospheric temperature does not increase as much as in the above case. For this reason, in this case, the air pressure reduction amount (Pd) described above does not exceed the specified value Pa.

  Therefore, after the pressure control valve 30 is changed from the ON state to the OFF state (that is, after the condition for stopping the supply of the pressurized air from the pressurizing means to the tire air chamber is satisfied), the air pressure is reduced in Step 105. By determining that the amount (Pd) is equal to or greater than the specified value Pa, it can be estimated that the adiabatic compression function of the air pump 20 is normal, and the above-described air pressure decrease amount (Pd) is not equal to or greater than the specified value Pa. By being judged, it can be estimated that the adiabatic compression function of the air pump 20 is not normal. Thereby, after the pressure control valve 30 changes from the ON state to the OFF state, the quality (normal / abnormal) of the adiabatic compression function of the air pump 20 can be estimated, and the air pump 20 accurately adiabatically compresses the atmosphere. Thus, it can be estimated whether or not the pressurized air is generated accurately.

  Further, in this embodiment, it is possible to notify the occupant that the adiabatic compression function of the air pump 20 is normal by displaying “normally adiabatic compression function” on the instrument panel display ID, and the adiabatic compression of the air pump 20 It is possible to inform the occupant that the function is not normal by displaying “abnormal adiabatic compression function” on the instrument panel display unit ID.

  Further, in this embodiment, an air pump 20 that is driven as the wheel B rotates is employed as a pressurizing unit that adiabatically compresses the atmosphere to generate pressurized air. In order to determine whether the adiabatic compression function of the air pump 20 is good or bad (normal / abnormal) from the detection value of the pressure sensor S1 while the vehicle is stopped, an error caused by a change in tire air pressure that occurs when overcoming road surface irregularities when the vehicle is running. It is possible to prevent the determination.

  In the above-described embodiment, the air pressure generation device A including the air pump 20 that is assembled to the axle hub 11 and driven as the wheel B rotates is implemented. However, the electric motor is assembled to the vehicle body. It is also possible to carry out using an air pressure generating device equipped with an air pump driven by. Moreover, in the said embodiment, although implemented using the mechanical control valve apparatus V which is not equipped with an electric actuator, the electric actuator by which operation | movement is controlled by electric control unit ECU based on the output signal from pressure sensor S1 It is also possible to use an electric control valve device that is equipped with (for example, an electromagnetic solenoid) and operates in the same manner as the control valve device V of the above embodiment.

  In the above embodiment, the pressurized air cannot be supplied to the tire air chamber Rb when the air pressure (P) of the tire air chamber Rb increases from the upper limit set value P2 to the lower limit set value P1. Yes, pressurized air can be supplied to the tire air chamber Rb when the air pressure (P) of the tire air chamber Rb decreases from the lower limit set value P1 to the upper limit set value P2 (that is, the tire air When the air pressure (P) in the chamber Rb rises to the upper limit set value P2, it is when the stop condition for stopping the supply of pressurized air from the air pump 20 to the tire air chamber Rb is satisfied.) Control valve device V However, when an electric control valve device is adopted instead of the control valve device V, the air pressure (P) of the tire air chamber Rb rises to the upper limit set value P2 and then reaches the lower limit set value P1. Until it falls When the tire air chamber Rb cannot be supplied with pressurized air and the air pressure (P) of the tire air chamber Rb decreases to the lower limit set value P1 until the drive time of the air pump reaches the set time, the tire Pressurized air can be supplied to the air chamber Rb (that is, when the supply time of the pressurized air from the air pump to the tire air chamber Rb reaches a set time, pressurization from the air pump to the tire air chamber Rb is possible. It is also possible to set and implement an electric control valve device so that the stop condition for stopping the supply of air is satisfied).

  Moreover, in the said embodiment, it comprised so that a passenger | crew could be notified by displaying the determination result in step 105 (result of whether the adiabatic compression function of the air pump 20 is normal) on the instrument panel display unit ID. Although implemented, the determination result in step 105 may be configured to be notified to the occupant with a notification sound through a speaker.

1 is an overall configuration diagram schematically illustrating an embodiment of a tire pressure control device according to the present invention. It is the principal part longitudinal cross-sectional front view which showed the tire air chamber shown in FIG. 1, the pneumatic pressure production | generation apparatus, and a part of control valve apparatus in detail. It is sectional drawing of the air pressure production | generation apparatus and control valve apparatus which were shown in FIG. 1 and FIG. It is the flowchart which showed the program which the microcomputer of the electric control apparatus shown in FIG. 1 performs.

Explanation of symbols

A ... Air pressure generating device, 20 ... Air pump, V ... Control valve device, 30 ... Pressure control valve, 40 ... Adjusting device, 50 ... Relief valve, B ... Wheel, B1 ... Wheel, B2 ... Tire, Rb ... Tire air chamber , S1 ... Pressure sensor, S2 ... Stroke sensor, ECU ... Electric control device, ID ... Instrument panel display

Claims (5)

  An air pressure generating device that includes a pressurizing unit that generates compressed air by adiabatically compressing the atmosphere, and that can supply the pressurized air generated by the pressurizing unit to the tire air chamber of the wheel, and detects the air pressure of the tire air chamber A pressure sensor for supplying pressurized air to the tire air chamber from the pressurizing means when the air pressure drops to a lower limit set value, and from the pressurizing means to the tire air chamber when a stop condition is satisfied A tire pressure control apparatus comprising a control device for stopping supply of pressurized air to the tire, wherein the air pressure is maintained within a set range, wherein the pressurized air from the pressurizing means to the tire air chamber Time measuring means for measuring an elapsed time from when the supply of the gas is stopped, computing means for calculating the amount of decrease in the air pressure during the predetermined time when the elapsed time reaches the predetermined time, and the air pressure reduction There tire-pressure control apparatus characterized by comprising a determination means for determining whether or not at least a prescribed value.   The tire pressure control device according to claim 1, further comprising a notification unit that notifies a determination result by the determination unit.   The tire pressure control device according to claim 1 or 2, wherein the stop condition is satisfied when the air pressure increases to an upper limit set value.   The tire according to claim 1 or 2, wherein the stop condition is satisfied when a supply time of pressurized air from the pressurizing means to the tire air chamber reaches a set time. Pneumatic control device. The tire pressure control device according to claim 1, wherein the pressurizing means is an air pump driven in accordance with the rotation of the wheel.

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