JP2007278796A - Air flow rate calculating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air flow rate calculating apparatus capable of accurately detecting a leakage abnormality of air in a pneumatic circuit including an air chamber. <P>SOLUTION: The air flow rate calculating apparatus comprises: a pressure sensor S1 for detecting an air pressure of a tire air chamber Rb included in a wheel B; a tire air pressure generating device A capable of being driven and stopped, which can supply pressurized air to the tire air chamber Rb in its driven state, and can not supply the pressurized air to the tire air chamber Rb in its stopped state; and an electric control unit ECU. The electric control unit ECU includes a leakage air flow rate calculating means which calculates a flow rate of the air leaking from the pneumatic circuit including the tire air chamber Rb, based on dropping of the air pressure in the tire air chamber Rb in the stopped state of the tire air pressure generating device A. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes an air chamber of a structure (for example, a wheel) and a pneumatic pressure generating device (for example, a pneumatic pump device driven by the rotation of the wheel) capable of supplying pressurized air to the air chamber. The present invention relates to an air flow rate calculation device that is provided in a pneumatic control device and that can calculate the flow rate of air leaked from a pneumatic circuit including the air chamber.

A pressure sensor that detects air pressure (tire pressure) of an air chamber of a structure (wheel) and a pressure generation device (tire pressure control unit that increases or decreases tire pressure) that can supply pressurized air to the air chamber include, for example, Is shown in Patent Document 1 below.
JP 2005-41257 A

  In the tire air pressure control device described in Patent Document 1 described above, the tire air pressure control unit is controlled based on data from various sensors including a pressure sensor, and is configured to increase / decrease the tire air pressure. Yes.

  By the way, with the above-described configuration of Patent Document 1, it is not possible to detect the leakage air flow rate in the pneumatic circuit including the air chamber and the air pressure generation device. For this reason, it is impossible to detect a leakage abnormality in the pneumatic circuit.

  The present invention has been made to cope with the above-described problems, and an air flow rate calculation device according to the present invention includes a pressure sensor that detects the air pressure of an air chamber, and can be driven and stopped, and pressurizes the air chamber during driving. An air pressure generating device capable of supplying air and not capable of supplying pressurized air to the air chamber when stopped, and the air pressure generated when the air pressure generating device is stopped (when pressurized air cannot be supplied to the air chamber). There is a feature in that a leakage air flow rate calculating means for calculating a leakage air flow rate from the pneumatic circuit including the air chamber based on the decrease is provided.

  In this case, the leakage air flow rate calculation means includes a stop determination unit that determines stop of the air pressure generation device, and a first time point during the stop when the stop determination unit determines that the air pressure generation device is stopped. A first time remaining air amount calculation unit during stop that calculates a residual air amount in the air pressure circuit based on an air pressure detected by the pressure sensor, and a predetermined time after a first time point during the stop of the air pressure generating device A second time remaining air amount calculation unit during stop that calculates a residual air amount in the pneumatic circuit at a second time point based on an air pressure detected by the pressure sensor, and a first time point remaining air amount calculation unit during stop. The air pressure circuit is based on the difference between the residual air amount at the first time point during stop calculated in step 2 and the residual air amount at the second time point during stop time calculated by the second time point residual air amount calculator during stop. Leaking air in It is also possible and a leakage air flow rate calculator for calculating the amount.

  In the air flow rate calculation device according to the present invention, it is possible to calculate and estimate the residual air amount in the pneumatic circuit including the air chamber from the air pressure of the air chamber detected by the pressure sensor. Including air chambers based on a decrease in the amount of residual air in the pneumatic circuit at the time of stoppage (when pressurized air cannot be supplied to the air chamber, that is, when supply of pressurized air is stopped) It is possible to calculate and estimate the leakage air flow rate from the pneumatic circuit, and it is possible to estimate the leakage abnormality of the pneumatic circuit based on this leakage air flow rate. For this reason, it is possible to detect an abnormality in the pneumatic circuit when the leakage air flow rate exceeds the allowable upper limit of leakage, and more accurately detect the abnormality in the pneumatic circuit than in the cases of the prior art described above. It is possible to detect.

  In the implementation of the present invention, the air flow rate calculation device calculates a supply air flow rate for calculating a supply air flow rate supplied from the air pressure generation device to the pneumatic circuit based on an increase in the air pressure when the air pressure generation device is driven. Computation means is provided, and the air pressure generation device is moved from the air pressure generation device to the air chamber when the air pressure generation device is driven based on the supply air flow rate calculated by the supply air flow rate calculation means and the leakage air flow rate calculated by the leakage air flow rate calculation means. It is also possible to provide a discharge air flow rate calculation means for calculating the flow rate of the discharge air discharged toward.

  In this case, the supply air flow rate calculation means includes a drive determination unit that determines the drive of the air pressure generation device, and a first time point during the drive when the drive determination unit determines the drive of the air pressure generation device. A first air-time remaining air amount calculation unit that calculates a residual air amount of the air pressure circuit based on an air pressure detected by the pressure sensor, and a first time after a first time during the driving of the air pressure generating device. The remaining air amount of the pneumatic circuit at two points in time is calculated based on the air pressure detected by the pressure sensor, and is calculated by the second time point residual air amount calculating unit during driving and the first point of remaining air amount calculating unit during driving. From the air pressure generating device based on the difference between the residual air amount at the first driving time point and the residual air amount at the second driving time point calculated by the second driving time residual air amount calculating unit. Air pressure It is also possible and a supply air flow rate calculation unit for calculating the feed flow rate of air supplied to.

  In the above-described air flow rate calculation device according to the present invention, the amount of residual air in the pneumatic circuit when the air pressure generating device is stopped, that is, the leakage air flow rate from the pneumatic circuit including the air chamber based on the decrease in the air pressure of the air chamber. And is supplied from the air pressure generating device to the air pressure circuit based on the increase in the amount of residual air in the air pressure circuit when the air pressure generating device is driven, i.e., the air pressure in the air chamber is increased. It is possible to calculate and estimate the supply air flow rate, and calculate the discharge air flow rate discharged from the air pressure generation device toward the air chamber when the air pressure generation device is driven from the above-described leakage air flow rate and supply air flow rate. Can be estimated. For this reason, it is possible to estimate an air pressure generation abnormality (pump discharge abnormality) in the air pressure generation device when the discharge air flow rate falls below the discharge allowable lower limit value.

  In carrying out the present invention, the air flow rate calculation device includes a temperature sensor that detects the air temperature of the air chamber, and the residual air amount is corrected according to the air temperature detected by the temperature sensor. Is also possible. In this case, the amount of residual air in the pneumatic circuit can be calculated with high accuracy, and the amount of air leaked from the pneumatic circuit can be calculated with high accuracy. Is possible.

  In carrying out the present invention, the structure may be a wheel, and the air chamber may be a tire air chamber formed by a wheel of a wheel and a tire. In this case, the air pressure generating device may be a pneumatic pump device that is driven as the wheel rotates. In this case, it is possible to implement the present invention in the tire pressure circuit of the vehicle, and in that case, it is possible to determine whether the air pressure generating device is driven or stopped based on the output of the vehicle speed sensor that the vehicle normally has. Thus, the vehicle speed sensor can also be used as a detection means for detecting driving / stopping of the air pressure generation device.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows an embodiment in which an air flow rate calculation device according to the present invention is implemented in a tire pressure control device for a vehicle. In the tire pressure control device, the tire pressure chambers of the tire air chamber Rb in a wheel B are formed by a tire pressure generation device A. The air pressure (P) is configured to be controlled. 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 includes a pressure sensor S1 for detecting the air pressure (P) of the tire air chamber Rb and the tire air chamber. A temperature sensor S2 for detecting the air temperature (T) of Rb is provided.

  As shown in detail in FIGS. 2 and 3, the tire air pressure generating device A is assembled to an axle hub 11 that rotates together with the wheels B, and a drive axle 12 is splined at the vehicle inner end of the axle hub 11. It is 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 tire air pressure generating device A is a pneumatic pump device that is driven as the wheel B rotates and stopped when the wheel B stops rotating, and is coaxial with the shaft portion (rotating shaft) 11 a of the axle hub 11. The air pump 20, the pressure control valve 30, and the adjusting device 40 are provided, and the relief valve 50 is provided coaxially inside the pressure control valve 30. 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 can supply pressurized air to the tire air chamber Rb of the wheel B through the pressure control valve 30 based on the rotation of the wheel B, and to the non-rotatable cylindrical member 21 and the shaft portion 11 a of the axle hub 11. A formed rotatable cylinder 22 and a piston 23 as a reciprocating body are provided, and a cam member 24 and a pair of cam followers 25 are provided.

  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 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 axial elongated holes 22a are guide means for guiding the piston 23 and the cam followers 25 so as to be able to rotate integrally with the cylinder 22 and reciprocate in the axial direction, and are formed at intervals of 180 degrees in the circumferential direction of the cylinder 22. Has been. 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 radial communication hole provided in the cylinder head 22B, and the pressurized air in the discharge passage 22d enters the air chamber Ra2 formed between the valve body 31 and the stopper 32 of the pressure control valve 30. Pressure 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 the cylinder inner hole 22b of the cylinder 22 via a pair of annular seal members 28 and 29, and is assembled to the cylinder 22 so as to be able to rotate integrally and reciprocate in the axial direction. The piston 23 has an annular groove 23a and a through hole 23b extending in the 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 does not change in volume even when the piston 23 reciprocates in the 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 composed of a pair of cam sleeves 24A and 24B connected in the axial direction, and is provided integrally with the cylindrical member 21 (not axially movable and non-rotatable). In contrast, they 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 an axial load (a load in the horizontal direction in the drawing) and a radial load (a load in the vertical direction in the drawing) from the ball 25c of each cam follower 25. The shape is V-shaped, and is formed in an even period (for example, two periods) 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 radial direction, that is, a ball 25c, and rotates relative to the cam member 24. To move in the axial direction.

  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 of being rotatably fitted to the small diameter end portion of the shaft 25a, and the cam follower 25 is moved in the axial direction. It is possible to roll along the axial long hole 22 a 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 limits the supply of pressurized air from the pump chamber Ro to the tire air chamber Rb when the pressure of the pressurized air supplied from the pump chamber Ro to the tire air chamber Rb reaches the first set value P1 ( This is a limiting means for stopping), is assembled in the cylinder head 22B, includes a valve body 31 and a stopper 32, engages with the valve body 31 via a spring retainer 33, and moves the valve body 31. And a compression coil spring 34 which can control the moving position and can adjust the urging force to the valve body 31 by the adjusting device 40.

  The valve body 31 is assembled in an airtight and axially movable manner in the cylinder head 22B via a discharge check valve Vo and an annular seal member 35 assembled on the outer periphery. In addition, an air chamber Ra1 that communicates with the discharge passage 22d is formed, and an air chamber Ra2 that communicates with the stopper 32 through the discharge passage 22d through the pressure guiding passage 22e is formed. 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, when the pressure of the pressurized air supplied from the pump chamber Ro to the tire air chamber Rb is less than the first set value P1, the valve body 31 is held at the illustrated position, and the communication path The communication between 31a and the suction passage 22f is blocked by the suction check valve Vi. For this reason, 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 communication between the communication passage 31a and the suction passage 22f is blocked to restrict the air flow from the pump chamber Ro to the atmosphere, and the discharge check valve Vo restricts the air flow from the tire air chamber Rb to the pump chamber Ro. 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 the pressure control valve 30, when the pressure of the pressurized air supplied from the pump chamber Ro to the tire air chamber Rb is equal to or higher than the first set value P1, the valve body 31 is biased by the compression coil spring 34 ( More specifically, it moves in the axial direction by a predetermined amount from the illustrated position against the urging force of the compression coil spring 34 and the urging force of the compression coil spring 52, which will be described later, and the communication passage 31a is connected to the suction check valve Vi. Regardless, it communicates with the suction passage 22f. 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 spring 34 or the like, the stepped portion of the valve body 31 is attached to the annular seal member 36 assembled to the inner periphery of the stopper 32. It is in contact. 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 S3 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.

  When the pressure of the pressurized air supplied from the pump chamber Ro to the tire air chamber Rb, that is, the pressure in the air chamber Ra1, is greater than or equal to the second set value P2, which is higher than the first set value P1, the relief valve 50 is pressurized air. The valve body 51 that can open and close the relief passage 31c provided in the valve body 31 is engaged with the valve body 51 at one end (movable side end). A compression coil spring 52 that regulates the movement timing of the valve body 51 (the opening timing of the relief passage 31c) is provided.

  The valve body 51 is assembled so as to be movable in the axial direction within the valve body 31 of the pressure control valve 30, and has almost no resistance to the rod portion 45 of the stroke sensor S3 (the movable portion during adjustment of the stroke sensor S3). A rod portion that is relatively movable in the axial 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 first set value P1 and the second set value P2 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 axial direction against the biasing force of the compression coil spring 34, and the air chamber Ra1 and the relief passage 31c communicate with each other through the seal member 38. Only, 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 temperature sensor S2 (air of the tire air chamber Rb). The electric signal indicating the temperature (T)) and the output of the stroke sensor S3 (the electric signal indicating the ON / OFF state of the pressure control valve 30 and the electric signal indicating the amount of movement of the adjusting screw 42) are wirelessly transmitted to the electric control unit ECU. It is configured to be entered.

  In addition, an electric signal representing a vehicle speed (also wheel speed (Wr)) detected and output by the vehicle speed sensor S4 is input to the electric control unit ECU. The electric control unit ECU also includes a pneumatic circuit including the tire air chamber Rb (the tire air chamber Rb and an air passage communicating with the tire air chamber Rb, for example, a communication passage Ba provided in the wheel B, a discharge passage 11b provided in the axle hub 11. Instrument panel display part ID which can display “leak abnormality” from the discharge passage 22d and the like provided in the cylinder 22 and can display “pump discharge abnormality” is electrically connected.

  The electric control unit ECU includes a microcomputer that repeatedly executes a program corresponding to the flowcharts of FIGS. 4 and 5 every predetermined calculation cycle (for example, 1 second), and includes a pressure sensor S1, a temperature sensor S2, and a stroke sensor. Based on the outputs of S3 and the vehicle speed sensor S4, the leakage air flow rate Mr from the pneumatic circuit including the tire air chamber Rb and the tire air pressure generating device A are discharged toward the tire air chamber Rb when the tire air pressure generating device A is driven. It is possible to calculate the discharge air flow rate Md.

  In this embodiment configured as described above, when the ignition switch (not shown) of the vehicle is turned on, the microcomputer of the electric control unit ECU corresponds to the flowcharts of FIGS. 4 and 5. Is repeatedly executed every predetermined calculation cycle (every second), and the pressure control valve 30 is in an OFF state (a state in which pressurized air cannot be supplied toward the tire air chamber Rb) when the vehicle is stopped and the vehicle is running. ), The leakage air flow rate Mr from the pneumatic circuit including the tire air chamber Rb is calculated, and “leak abnormality” is determined based on the leakage air flow rate Mr. Further, when the pressure control valve 30 is in an ON state (a state in which pressurized air can be supplied toward the tire air chamber Rb) while the vehicle is running, discharge is performed from the tire air pressure generating device A toward the tire air chamber Rb. The discharge air flow rate Md is calculated, and “pump discharge abnormality” is determined based on the discharge air flow rate Md and the vehicle speed (wheel speed) Wr at that time.

  The microcomputer of the electric control unit ECU starts the process in step 101 of FIG. 4, and in step 102, the output (P) of the pressure sensor S1, the output (T) of the temperature sensor S2, and the vehicle speed sensor S4. The output (Wr) is read and stored. Further, in step 103, the microcomputer of the electric control unit ECU determines the residual air amount M of the pneumatic circuit including the tire air chamber Rb based on the gas state equation PVo = MRT and the output values (P, T) described above. Is calculated and stored. Note that P in the above equation of state of gas is “absolute pressure”, T is “absolute temperature”, and M is “air weight”. Vo is “the volume of the pneumatic circuit including the tire air chamber Rb”, R is the “air gas constant”, and Vo and R are obtained in advance by experiment or analysis and do not change (constant values). ).

  Further, the microcomputer of the electric control unit ECU determines whether or not the output (Wr) of the vehicle speed sensor S4 is zero in Step 104 of FIG. 4 (the tire air pressure generating device A is stopped and pressurizing the tire air chamber Rb). Whether or not air cannot be supplied) is determined, and if “Yes” is determined (when pressurized air cannot be supplied to the tire air chamber Rb), step 105 is executed and “No” is determined. If so, step 111 in FIG. 5 is executed.

  Further, in step 105 of FIG. 4, the residual air amount M (current calculated value) obtained in step 103 and the residual air amount Mo (previous calculated value, that is, when the program is executed one second before) (Computed value) and the current residual air amount M is smaller than the previous residual air amount Mo (when air leaks from the pneumatic circuit including the tire air chamber Rb), "Yes" Steps 106 and 107 are performed, and if the current residual air amount M is not smaller than the previous residual air amount Mo, it is determined “No” and steps 109 and 110 are performed.

  In step 106 of FIG. 4, the leakage air flow rate Mr is calculated and stored based on the difference (Mo−M) between the previous residual air amount Mo and the current residual air amount M. Further, in step 107, it is determined whether or not the leakage air flow rate Mr is larger than a preset leak allowable upper limit value Mr1, and if it is determined "Yes", steps 108, 109, 110 are executed, If it is determined “No”, steps 109 and 110 are executed. In step 108, display of “leak abnormality” is instructed, and “leak abnormality” is displayed on the instrument panel display section ID. In step 109, the current residual air amount M is rewritten and stored as the previous residual air amount Mo. In step 110, execution of the program is terminated.

  Since steps 101 to 110 in FIG. 4 described above are repeatedly executed when the tire pressure generating device A is stopped, in the second and subsequent executions in that case, the previous residual air amount Mo is the tire pressure generation. When the stop of the device A is determined, the residual air amount in the pneumatic circuit at the first time point during the stop is the same as the remaining air amount M when the stop of the tire pressure generating device A is determined. It is the amount of residual air in the pneumatic circuit at the second time point (a predetermined time after the first time point) during the stop.

  On the other hand, in step 111 of FIG. 5, whether or not the pressure control valve 30 is in the ON state (pressure control valve 30) based on the output of the stroke sensor S3 (electrical signal indicating the ON / OFF state of the pressure control valve 30). Whether or not pressurized air can be supplied toward the tire air chamber Rb), and if “Yes” is determined, after executing steps 112, 113, 114, 115, and 116 in FIG. Steps 109 and 110 in FIG. 4 are executed, and when it is determined “No”, the above-described steps 105 to 110 in FIG. 4 are executed.

  In step 112 of FIG. 5, the supply air flow rate Mp supplied from the tire pressure generating device A to the pneumatic circuit including the tire air chamber Rb by the difference (M−Mo) between the current residual air amount M and the previous residual air amount Mo. Is calculated and stored. Further, in step 113, the discharge of the tire pressure generating device A is referred to the map (the map (not shown) showing the relationship between the allowable discharge lower limit Md1 of the tire pressure generating device A and the vehicle speed) from the output (Wr) of the vehicle speed sensor S4. The allowable lower limit value Md1 is acquired and stored.

  Further, in step 114 of FIG. 5, the tire air pressure generating device A drives the tire air pressure generating device A from the supply air flow rate Mp obtained in step 112 and the leaked air flow rate Mr obtained in step 106 of FIG. 4. A discharge air flow rate Md discharged toward the tire air chamber Rb is calculated and stored. In step 115, it is determined whether or not the discharge air flow rate Md is smaller than the allowable discharge lower limit Md1 acquired in step 113. If “Yes” is determined, step 116 is executed. Steps 109 and 110 in FIG. 4 are executed, and if “No” is determined, Steps 109 and 110 in FIG. 4 are executed. In step 116, display of “abnormal pump discharge” is instructed, and “abnormal pump discharge” is displayed on the instrument panel display section ID.

  In short, in this embodiment, the tire air chamber Rb is calculated from the air pressure (P) of the tire air chamber Rb detected by the pressure sensor S1 and the air temperature (T) of the tire air chamber Rb detected by the temperature sensor S2. It is possible to estimate the residual air amount M in the pneumatic circuit including (see Step 103 of FIG. 4), and when the tire air pressure generating device A stops supplying pressurized air (when the vehicle is stopped or When the vehicle is running and the pressure control valve 30 is in the OFF state), the air pressure including the tire air chamber Rb is reduced based on the decrease in the residual air amount M in the pneumatic circuit, that is, the decrease in the air pressure of the tire air chamber Rb and the temperature change. The leakage air flow rate Mr from the circuit can be estimated by calculation (see step 106 in FIG. 4). Estimating the leakage abnormality (to be determined at step 107 of FIG. 4) are possible. For this reason, it is possible to detect a leakage abnormality of the pneumatic circuit when the leakage air flow rate Mr exceeds the leakage allowable upper limit value Mr1, and the leakage abnormality of the pneumatic circuit is detected as compared with each case of the prior art described above. It is possible to detect accurately.

  Further, in this embodiment, the tire air chamber is based on the decrease in the residual air amount M in the pneumatic circuit when the tire air pressure generating device A stops supplying the pressurized air, that is, on the basis of the decrease in the air pressure of the tire air chamber Rb and the temperature change. It is possible to estimate the leakage air flow rate Mr from the air pressure circuit including Rb by calculating (see step 106 in FIG. 4), and the air pressure when the tire air pressure generating device A is driven (when pressurized air is supplied). The supply air flow rate Mp supplied to the pneumatic circuit from the tire air pressure generating device A is calculated based on the increase in the residual air amount M in the circuit, that is, the increase in the air pressure in the tire air chamber Rb and the temperature change (see step 112 in FIG. 5). ), And the tire air pressure is generated when the tire air pressure generating device A is driven from the leakage air flow rate Mr and the supply air flow rate Mp. It is possible to estimate the discharge air flow rate Md discharged toward the location A to the tire air chamber Rb by calculating (see step 114 of FIG. 5). For this reason, when the discharge air flow rate Md falls below the discharge allowable lower limit Md1, it is possible to estimate an abnormal air pressure generation (pump discharge abnormality) in the tire air pressure generating device A (determined in step 115 in FIG. 5). Is possible.

  Further, in this embodiment, a temperature sensor S2 for detecting the air temperature (T) of the tire air chamber Rb is provided, and the residual air in the pneumatic circuit according to the air temperature (T) detected by the temperature sensor S2. The quantity M is corrected. For this reason, it is possible to calculate the residual air amount M in the pneumatic circuit with higher accuracy than when calculating the residual air amount M in the pneumatic circuit with the air temperature in the tire air chamber Rb being constant (To). It is possible to calculate the above-described leakage air flow rate Mr and supply air flow rate Mp with high accuracy, and to accurately estimate the leakage abnormality of the pneumatic circuit and the abnormal air pressure generation (abnormal pump discharge) in the tire air pressure generation device A. Is possible.

  Further, in this embodiment, the present invention is applied to the tire pressure circuit of the vehicle, and the driving / stopping of the tire pressure generating device A is determined based on the output (Wr) of the vehicle speed sensor S4 normally provided in the vehicle (FIG. 4). Therefore, the vehicle speed sensor S4 can also be used as a detection means for detecting the driving / stopping of the tire air pressure generating device A.

  In this embodiment, when the tire air pressure generating device A is driven, the air pressure in the tire air chamber Rb increases by a predetermined pressure. For this reason, if the leakage air flow rate is calculated based on the decrease in the air pressure in the tire air chamber Rb when the tire air pressure generating device A is driven, the decrease in the air pressure includes the air pressure increased by driving the tire air pressure generating device A. Therefore, the leaked air flow rate calculated based on this decrease in air pressure includes air generated by driving the tire air pressure generating device A, and it is impossible to calculate only the leaked air flow rate Mr. However, when the tire air pressure generating device A stops driving and the air pressure in the tire air chamber Rb is not supplied from the tire air pressure generating device A to the tire air chamber Rb, the tire air pressure generating device A is driven. Therefore, only the leakage air flow rate Mr can be calculated by calculating the leakage air flow rate based on this decrease in air pressure.

  Further, in this embodiment, when the air flow rate discharged from the tire air pressure generating device A is calculated based on the air pressure of the tire air chamber Rb, if air leaks from the tire air chamber Rb, the air leak is generated. Compared to the case where it does not occur, the air pressure decreases by the amount of air leakage. For this reason, if the air flow rate calculated based on the decreased air pressure is the air flow rate discharged by the tire air pressure generating device A, the air flow rate leaked despite the tire air pressure generating device A discharged. The flow rate is not included, and an erroneous discharge air flow rate is calculated accordingly. However, in this embodiment, both the leaked air flow rate and the air flow rate supplied to the tire air chamber Rb are calculated and added together to include the leaked air flow rate discharged by the tire air pressure generating device A. It is possible to calculate the correct air flow rate.

  Further, in this embodiment, when the leak air flow rate Mr calculated in step 106 (leak air flow rate calculation means) in FIG. 4 exceeds the leak allowable upper limit value Mr1 (predetermined reference value), the tire air chamber Steps 107 and 108 (abnormality determination unit) for determining that there is a leakage abnormality in the pneumatic circuit including Rb are provided. Further, in this embodiment, when the discharge air flow rate Md calculated in step 114 (discharge air flow rate calculation means) in FIG. 5 falls below the discharge allowable lower limit Md1 (predetermined reference value), the tire air pressure is generated. Steps 115 and 116 (abnormality determination unit) for determining that the discharge of the apparatus A is abnormal are provided. For this reason, by displaying each abnormality described above on the instrument panel display ID (notifying the driver of the abnormality), the driver can recognize each abnormality described above, replacing the tire pressure generating device A, and the like. In addition, it is possible to take measures according to each situation such as measures against leakage of the pneumatic circuit including the tire air chamber Rb.

  In the embodiment described above, the volume of the pneumatic circuit including the tire air chamber Rb is set to a constant value (Vo) in the gas state equation in Step 103 of FIG. ) And a volume (V) that changes according to the air temperature (T). In this case, it is possible to calculate the residual air amount M, the leakage air flow rate Mr, the supply air flow rate Mp, and the like in the pneumatic circuit described above with higher accuracy than in the above embodiment. In carrying out the present invention, the air temperature (T) of the above-described embodiment is set to a constant value (To), and the residual air amount M, the leakage air flow rate Mr, the supply air flow rate Mp, etc. in the pneumatic circuit described above are simplified. It is also possible to calculate to. In this case, the temperature sensor S2 becomes unnecessary, and the device can be simplified.

  Further, in the above-described embodiment, the tire air pressure generating device A is an air pressure pump device that is driven as the wheel B rotates and is stopped when the wheel B stops rotating. It is also possible to implement the present invention in an embodiment in which the tire air pressure generating device is an electric pneumatic pump device configured to be driven by an electric motor that rotates regardless of the rotation of the wheel. In this case, the allowable discharge lower limit Md1 acquired in step 113 of FIG. 5 is set as a design value set at the time of designing the electric pneumatic pump device.

  In the above-described embodiment, the present invention is applied to the tire pneumatic circuit of the vehicle. However, the present invention is not limited to the pneumatic circuit (the structure has an air chamber other than the above-described embodiment). A pneumatic circuit that can supply pressurized air by driving the generating device but cannot supply pressurized air by stopping can also be implemented in the same manner as in the above-described embodiment or appropriately modified.

1 is an overall configuration diagram schematically showing an embodiment in which an air flow rate calculation device according to the present invention is implemented in a vehicle tire pressure control device. It is the principal part longitudinal cross-sectional front view which showed a part of the tire air chamber and tire air pressure production | generation apparatus shown in FIG. FIG. 3 is a cross-sectional view of the tire pressure generating device shown in FIGS. 1 and 2. It is the flowchart which showed a part of program which the microcomputer of the electric control apparatus shown in FIG. 1 performs. It is the flowchart which showed a part of other program which the microcomputer of the electric control apparatus shown in FIG. 1 performs.

Explanation of symbols

A ... Tire pressure generator, 20 ... Air pump, 30 ... Pressure control valve, B ... Wheel, B1 ... Wheel, B2 ... Tire, Rb ... Tire air chamber, S1 ... Pressure sensor, S2 ... Temperature sensor, S3 ... Stroke sensor , S4 ... Vehicle speed sensor, ECU ... Electric control device

Claims (7)

  A pressure sensor that detects the air pressure of the air chamber; and a pneumatic pressure generator that can be driven / stopped, can supply pressurized air to the air chamber when driven, and cannot supply pressurized air to the air chamber when stopped, and An air flow rate calculation device comprising leak air flow rate calculation means for calculating a flow rate of leak air from a pneumatic circuit including the air chamber based on a decrease in the air pressure when the air pressure generation device is stopped.   2. The air flow rate calculation device according to claim 1, wherein the leakage air flow rate calculation means includes a stop determination unit that determines stop of the air pressure generation device, and a stop determination unit that determines stop of the air pressure generation device. A stopped first time remaining air amount calculation unit that calculates a residual air amount in the pneumatic circuit at a first time point during the stop based on the air pressure detected by the pressure sensor, and the air pressure generating device is stopped A second time remaining air amount calculation unit during stoppage that calculates a residual air amount in the pneumatic circuit at a second time point after a predetermined time from the first time point based on an air pressure detected by the pressure sensor; The residual air amount at the first time point during stop calculated by the one-time residual air amount calculation unit, and the residual air amount at the second point in time calculated during the second time point remaining air calculation unit during stop The sky based on the difference of Air flow rate calculation apparatus characterized by comprising a leakage air flow rate calculator for calculating a leakage air flow rate in the pressure circuit.   The air flow rate calculation device according to claim 1, wherein the supply air flow rate calculation means calculates a flow rate of supply air supplied from the air pressure generation device to the pneumatic circuit based on an increase in the air pressure when the air pressure generation device is driven. And the air pressure generating device is driven from the air pressure generating device toward the air chamber when the air pressure generating device is driven based on the supply air flow rate calculated by the supply air flow rate calculating device and the leaked air flow rate calculated by the leaking air flow rate calculating device. An air flow rate calculation device comprising discharge air flow rate calculation means for calculating a discharge air flow rate to be discharged.   4. The air flow rate calculation device according to claim 3, wherein the supply air flow rate calculation means includes a drive determination unit that determines the drive of the air pressure generation device, and a drive determination unit that determines the drive of the air pressure generation device. A first driving time residual air amount calculation unit for calculating a residual air amount of the pneumatic circuit at a first time point during driving based on an air pressure detected by the pressure sensor; A second time remaining air amount calculation unit for driving that calculates a residual air amount of the pneumatic circuit at a second time point after a predetermined time from one time point based on an air pressure detected by the pressure sensor; and a first time point during driving. The difference between the residual air amount at the first driving time calculated by the residual air amount calculating unit and the residual air amount at the second driving time calculated by the second driving time residual air calculating unit. Based on the air pressure Air flow rate calculation apparatus characterized by comprising a supply air flow rate calculation unit for calculating the feed flow rate of air supplied to the pneumatic circuit from the deposition apparatus.   The air flow rate calculation device according to any one of claims 1 to 4, further comprising a temperature sensor that detects an air temperature of the air chamber, and the residual air amount according to the air temperature detected by the temperature sensor. Is an air flow rate calculation device characterized by being corrected.   The air flow rate calculation device according to any one of claims 1 to 5, wherein the structure is a wheel, and the air chamber is a tire air chamber formed by a wheel of the wheel and a tire. An air flow rate calculation device. 7. The air flow rate calculation device according to claim 6, wherein the air pressure generation device is a pneumatic pump device that is driven as the wheel rotates.

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