JP5867131B2 - Steering wheel axle weight estimation device - Google Patents

Description

  The present invention relates to a technique for estimating the axle load of a steering wheel shaft.

  Conventionally, as shown in Patent Document 1, a technique for estimating the loading weight of a vehicle by a vehicle height sensor has been disclosed.

  On the other hand, in recent years, a skid prevention device as shown in Patent Document 2 is mounted on large vehicles such as cargo vehicles and passenger transport vehicles. Such a skid prevention device stabilizes the turning behavior of the vehicle as much as possible by adjusting the braking force of the brake provided on each wheel of the vehicle when the turning behavior of the vehicle is disturbed. In such a large vehicle, the axle weight of the steering wheel shaft varies greatly depending on the passenger, so the behavior of the large vehicle differs greatly between the case where the axle weight of the steering wheel shaft is light and the case where the axle weight of the steering wheel shaft is heavy. . For this reason, it is important to determine the turning behavior of the vehicle in consideration of the axle weight of the steering wheel shaft in order to stabilize the turning behavior of the large vehicle by the skid prevention device.

JP-A 63-63924 JP-A-9-142273

  According to the technique disclosed in Patent Document 1, it is possible to estimate the axle load of the steering wheel shaft. However, in the estimation of the axle load of the steering wheel shaft by the technique disclosed in Patent Document 1, it is necessary to mount an additional vehicle height sensor, which increases the cost.

  The present invention has been made in view of such circumstances, and provides a technique for estimating the axle load of the steering wheel shaft without increasing the cost.

According to the invention according to claim 1, which has been made to solve the above-described problem, a steering wheel axle load estimation device including a pitman arm that transmits an operation force of a steering wheel to a steering wheel and swings in a vertical direction. a is, the steering angle detecting section for detecting a steering angle of the steering wheel, and on the basis of the said steering angle detected by the steering angle detection unit, the steering wheel axle load estimating unit for estimating a steering wheel axle load, the possess a determining vehicle weight state determination unit to vehicle weight condition of the vehicle, wherein the steering angle detection unit, vehicle weight of the vehicle is determined to be a predetermined vehicle weight state by the vehicle weight state determining unit When the vehicle weight state determination unit determines that the vehicle is in a vehicle weight state other than the predetermined vehicle weight state, the steering angle is detected as a comparative steering angle. And, the steering wheel axle load estimation unit, based on the steering angle difference of the reference steering angle and the comparative steering angle, said comparing steering angle by the steering angle detection unit estimates the steering wheel axle load when it is detected That is.

The invention according to claim 2 further includes a straight traveling state determination unit that determines whether or not the vehicle is traveling straight, according to claim 1, wherein the steering angle detection unit is operated by the vehicle weight state determination unit. When it is determined that the vehicle weight is in the predetermined vehicle weight state, and the steering angle detected when the straight traveling state determination unit determines that the vehicle is traveling straight is used as a reference steering angle. Detected when it is determined by the vehicle weight state determination unit that the vehicle is in a vehicle weight state other than the predetermined vehicle weight state, and when the vehicle is determined to be traveling straight by the straight-ahead state determination unit. The steering angle is detected as a comparative steering angle .

According to a third aspect of the present invention, in the first or second aspect , the steering angle detection unit detects the reference steering angle when the vehicle is in an unloaded state.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the difference between the steering angle difference and the steering wheel axle load is increased as the steering angle difference increases. A steering wheel axle weight information associated with the steering wheel axle weight so that an increase width of the steering wheel axle weight is increased. The steering wheel axle weight estimation section is configured to store the steering wheel axle weight information based on the steering wheel axle weight information and the steering angle. This is to estimate the steering wheel axle weight.

As a result of repeated research on an axle weight estimation device for a steered wheel, the inventor obtained the knowledge that "the vehicle equipped with a pitman arm that swings in the vertical direction has a correlation between the steered wheel axle weight and the steering angle". . According to the above knowledge, when the steering wheel axle weight changes, the amount of subsidence of the steering wheel with respect to the axle changes, and the pitman arm swings in the vertical direction, so that the steering angle changes according to the steering wheel axle weight.
Therefore, as in the invention according to claim 1, in a vehicle including a pitman arm that swings in the vertical direction, it is possible to estimate the steering wheel axle load based on the steering angle. For this reason, if the vehicle is equipped with a steering angle detection unit that detects the steering angle, it is possible to estimate the steering wheel axle weight only by adding a program. Can be estimated.
Further, the steering angle detection unit uses the steering angle when the vehicle weight determination unit determines that the vehicle weight is in a predetermined vehicle weight as a reference steering angle, and the vehicle weight determination unit determines the predetermined vehicle weight. When the vehicle weight state other than the state is determined, the steering angle is detected as the comparative steering angle, and the steering wheel axle weight estimation unit determines the steering angle based on the steering angle difference between the reference steering angle and the comparative steering angle. The steering wheel axle weight when the comparison steering angle is detected by the detection unit is estimated. Thus, by evaluating the comparative steering angle based on the reference steering angle in a predetermined vehicle weight state, the steering wheel axle load can be estimated with higher accuracy.

In the invention according to claim 2, the steering angle detection unit detects the steering angle detected when the straight traveling state determination unit determines that the vehicle is traveling straight as the reference steering angle and the comparative steering angle. More specifically, the above-mentioned knowledge is that “the steering angle of the steered wheel is an angle changed by an amount corresponding to the steered wheel axle weight with reference to the steered angle corresponding to the turning angle of the steered wheel”. Further, the detection of the straight traveling state of the vehicle can be detected more reliably than the detection of the predetermined turning state of the vehicle. Thus, according to the invention described in claim 2, since the reference steering angle and the comparative steering angle are detected in the straight traveling state that can be reliably detected, the straight traveling state, that is, the state in which the turning angle of the steered wheels is substantially zero. The reference steering angle and the comparative steering angle at can be detected more reliably. Then, by estimating the steering wheel axle weight based on the reference steering angle and the comparative steering angle when the turning angle of the steering wheel is substantially 0, the steering wheel axle weight can be estimated more reliably. Further, since the frequency with which the vehicle is traveling straight is higher than the frequency with which the vehicle is turning, the steering wheel axle load can be estimated more frequently and more reliably.

According to the third aspect of the present invention, the steering angle detector detects the reference steering angle when the vehicle is in an unloaded state. Thus, since the axle load of the steering wheel axle when the vehicle is in the unloaded state is known in advance from the design value, the steering wheel axle weight can be reliably estimated.

The inventor has further obtained the knowledge that “the correlation between the steering angle difference and the steering wheel axle load increases, the greater the steering angle difference, the greater the increase in the steering wheel axle load relative to the increase in the steering angle difference”.
Therefore, as in the invention according to claim 4 , the steering wheel axle that correlates the steering angle difference and the steering wheel axle weight such that the larger the steering angle difference is, the larger the increase width of the steering wheel axle weight with respect to the increase width of the steering angle difference is. By estimating the steering wheel axle weight based on the weight information and the steering angle, the steering wheel axle weight can be estimated with higher accuracy.

1 is a schematic diagram showing an embodiment of a vehicle on which a steered wheel vehicle weight estimation device of the present invention is mounted. (A) is a view on arrow A in FIG. 1, (B) is a view on arrow B in FIG. 1, and (C) is a view on arrow C in FIG. It is explanatory drawing for demonstrating the outline | summary of this invention, (A) is a figure showing the circumference | surroundings of the steering wheel axis at the time of no loading, (B) is a figure showing the circumference | surroundings of the steering wheel axis at the time of loading. . (A) It is the graph showing the relationship between a steering angle difference and the sinking amount of the steering wheel axis | shaft with respect to the time of no loading. (B) Mapping data representing the relationship between the steering angle difference and the steering wheel axle load. It is a flowchart of the reference | standard steering angle acquisition process which is a control program performed by brake control ECU shown in FIG. It is a flowchart of a steering wheel axle load estimation process which is a control program executed by the brake control ECU shown in FIG.

(Description of vehicle configuration)
Hereinafter, an embodiment of a steered wheel axle weight estimation device of the present invention will be described with reference to the drawings. The vehicle 100 of this embodiment is a large vehicle such as a cargo vehicle or a passenger transport vehicle, and is a vehicle whose vehicle weight and axle load vary greatly depending on the passenger. As shown in FIGS. 1 and 2, the vehicle 100 includes a frame 10, left and right front wheels Wfl and Wfr, left and right rear wheels Wrl and Wrr, a steering wheel shaft 21, a first steering wheel knuckle 22, and a second steering wheel knuckle. 23, drag link 25, pitman arm 26, shock absorbers 29, 53, steering wheel 31, steering shaft 32, steering sensor 33, power steering device 34, leaf springs 41, 51, rear wheel shaft 52, and brake devices Brl, Brr, Brl and Brr are provided.

  As shown in FIG. 1, the frame 10 extends in the front-rear direction of the vehicle 100 and has a pair of side members 11 disposed in parallel with the width direction of the vehicle 100 and a plurality of crosses that connect the pair of side members 11. It is composed of members 12. Hanger brackets 45 and 46 are attached to the front lower portion of the side member 11. As shown in FIG. 2A, the leaf spring 41 is disposed below the side member 11 along the side member 11, and the front and rear ends thereof are supported by hanger brackets 45 and 46, respectively.

  Below the front of the frame 10, a steering wheel shaft 21 is disposed orthogonal to the side member 11, and a leaf spring 41 is placed on the steering wheel shaft 21. The steering wheel shaft 21 is suspended and supported at a middle portion in the longitudinal direction of the leaf spring 41 by a pair of U bolts 42 and a fixture 43. That is, a plate-shaped fixing bracket 43 is disposed at the lower portion of the steering wheel shaft 21, and each lower end portion of the U bolt 42 penetrates from a circular hole (not shown) formed at the four corners of the fixing bracket 43 from above. The steering wheel shaft 21 is suspended and supported by the leaf spring 41 by tightening a nut 44 that is screwed into a lower end screw portion that passes through the fixing bracket 43 of each U bolt 42. With such a structure, the steering wheel shaft 21 is suspended and supported by the leaf spring 41, so that even when an excessive force is applied to the steering wheel shaft 21, the steering wheel shaft 21 slightly moves against the leaf spring 41. The movable portion is movable, and the attachment portion between the steering wheel shaft 21 and the leaf spring 41 is prevented from being broken. With this structure, the steering wheel shaft 21 can move in the vertical direction with respect to the frame 10.

  As shown in FIG. 1, the lower end of the shock absorber 29 is rotatably supported at a position slightly inside the both ends of the steering wheel shaft 21. The upper end of the shock absorber 29 is rotatably supported by a bracket (not shown) attached to the side member 11.

  At both ends of the steering wheel shaft 21, kingpin shafts 21a are formed in the vertical direction. A first steering wheel knuckle 22 and a second steering wheel knuckle 23 are attached to each kingpin shaft 21a so as to be swingable in the horizontal direction. The first and second steering wheel knuckles 22 and 23 are formed with axles 22 a and 23 a that protrude to the side of the vehicle 100. A hub (not shown) is rotatably attached to each of the axles 22a and 23a, and a right front wheel Wfr and a left front wheel Wfl are attached to the hub. The first and second steering wheel knuckles 22 and 23 are provided with brake devices Bfr and Bfl that apply braking force to the right front wheel Wfr and the left front wheel Wfl, respectively.

  The first and second steering wheel knuckles 22 and 23 are respectively formed with knuckle arms 22b and 23b protruding forward from the kingpin shaft 21a. A tie rod 24 is rotatably connected to knuckle arm ends 22c and 23c formed at the tips of the knuckle arms 22b and 23b. With such a structure, when the first steering wheel knuckle 22 swings, force is transmitted to the second steering wheel knuckle 23 by the tie rod 24, and the second steering wheel knuckle 23 swings the same as the first steering wheel knuckle 22. Swing in the direction.

  The first steering wheel knuckle 22 is formed with a substantially C-shaped transmission arm 22d extending from the kingpin shaft 21a toward the inside of the vehicle 100 (side member 11 side) so as to bypass the shock absorber 29.

  As shown in FIGS. 1 and 2, a power steering device 34 is attached to the front of the frame 10 via a bracket (not shown). The steering force of the steering wheel 31 is input to the power steering device 34 by the steering shaft 32. The power steering device 34 is rotatably provided with an output shaft 34 a that protrudes in the width direction of the vehicle 100. The steering force of the steering wheel 31 input from the steering shaft 32 is amplified by the power steering device 34 and output from the output shaft 34a.

  A pitman arm 26 that swings in the vertical direction about the output shaft 34a is attached to the output shaft 34a. Both ends of the drag link 25 are rotationally connected to a first fulcrum 22e formed at the end of the transmission arm 22d and a second fulcrum 26a formed at the tip of the pitman arm 26, respectively. With such a structure, the operating force of the steering wheel 31 is such that the steering shaft 32, the power steering device 34, the pitman arm 26, the drag link 25, the steering wheel knuckle 22 (tie rod 24, steering wheel knuckle 23), and the steering wheel Wf, Steering wheels Wf and Wfr are rotated and steered by being sequentially transmitted to Wfr. In the present embodiment, the drag link 25 is disposed so as to become lower toward the rear of the vehicle 100.

  A leaf spring 51 is attached to the rear of the side member 11, and a rear wheel shaft 52 disposed so as to be orthogonal to the side member 11 is suspended and supported by the leaf spring 51. The suspension support structure for the rear wheel shaft 52 to the leaf spring 51 is the same as the suspension support structure for the steering wheel shaft 21 to the leaf spring 41 described above. Similar to the steering wheel shaft 21, the rear wheel shaft 52 is also provided with a shock absorber 53. Left and right rear wheels Wll and Wir are rotatably attached to both ends of the rear wheel shaft 52. Further, at both ends of the rear wheel shaft 52, brake devices Brl and Brr for applying a braking force to the left and right rear wheels Wll and Wir are provided.

  The brake actuator 65 is provided between the master cylinder (not shown) and each brake device Bfl, Bfr, Brl, Brr and is automatically formed regardless of whether or not the brake pedal (not shown) is operated. It is a device that can apply pressure to each brake device Bfl, Bfr, Brl, Brr and generate a friction braking force on the corresponding wheels Wfl, Wfr, Wrl, Wrr. Of course, the brake actuator 65 applies a control hydraulic pressure to each brake device Bfl, Bfr, Brl, Brr according to the operation amount of the brake pedal, and generates a friction braking force on the corresponding wheels Wfl, Wfr, Wrl, Wrr. Let

  A steering sensor 33 that detects the steering angle of the steering wheel 31 by detecting the rotation angle (steering angle) of the steering shaft 32 is disposed in the vicinity of the steering shaft 32. The vehicle 100 includes a yaw rate sensor 62 and an acceleration sensor 63 for detecting the turning behavior of the vehicle 100. The yaw rate sensor 62 is assembled at a position near the center of gravity of the vehicle body and detects the yaw rate generated in the vehicle 100. The acceleration sensor 63 is assembled at a position near the center of gravity of the vehicle body, and detects a lateral acceleration and a longitudinal acceleration generated in the vehicle 100.

  The vehicle 100 includes wheel speed sensors Sfl, Sfr, Srl, Srr. Wheel speed sensors Sfl, Sfr, Srl, Srr are provided in the vicinity of each wheel Wfl, Wfr, Wrl, Wrr, and brake a pulse signal having a frequency according to the rotation of each wheel Wfl, Wfr, Wrl, Wrr. It is output to the control ECU 61.

  The brake control ECU 61 receives the detection signals from the steering sensor 33, the yaw rate sensor 62, and the acceleration sensor 63 and the detection signals from the wheel speed sensors Sfl, Sfr, Srl, Srr, and calculates various physical quantities. That is, the brake control ECU 61 calculates the steering angle and steering amount of the steering wheel 31 by the driver output from the steering sensor 33, or outputs a detection signal corresponding to the yaw rate generated in the vehicle 100 output from the yaw rate sensor 62. The yaw rate is calculated based on this, or the lateral acceleration is calculated based on a detection signal corresponding to the lateral acceleration generated in the vehicle 100 output from the acceleration sensor 63. Further, the brake control ECU 61 determines the wheel speed of each wheel Wfl, Wfr, Wrl, Wrr, the vehicle speed V of the vehicle 100, the wheel speed sensor Sfl, the wheel speed sensor Sfl, based on detection signals from the wheel speed sensors Sfl, Sfr, Srl, Srr. Based on the detection signal from Sfr, the turning state of the vehicle 100 is also calculated.

  The brake control ECU 61 includes a microcomputer (not shown), and the microcomputer includes storage units such as an input / output interface, a CPU, a RAM, a ROM, and a nonvolatile memory that are connected via a bus. . The CPU executes a program corresponding to the flowcharts shown in FIGS. The RAM temporarily stores variables necessary for the execution of the program, and the ROM stores the program and mapping data described later (shown in FIG. 4B).

  When the brake control ECU 61 calculates the behavior of the vehicle 100 based on the calculated steering amount of the steering sensor 33, the yaw rate, acceleration, and turning state of the vehicle 100, and determines that the vehicle 100 is about to skid. In addition, by outputting a control signal to the brake actuator 65, a control hydraulic pressure is applied to each brake device Bfl, Bfr, Brl, Brr, and the vehicle motion is controlled (side slip prevention control) so that the vehicle 100 does not skid. Note that such skid prevention control is a well-known technique described in Japanese Patent Application Laid-Open No. 9-142273, Japanese Patent Application Laid-Open No. 2003-237420, and the like, and therefore will not be described here.

(Outline of the present invention)
The outline of the present invention will be described below with reference to FIGS. The steering wheel shaft 21 moves up and down depending on whether or not there is a cargo passenger in the vehicle 100. Accordingly, the first fulcrum 22e formed at the end of the transmission arm 22d also moves up and down.

  If the distance between the first fulcrum 22e and the second fulcrum 26a is 1, the horizontal distance a between the first fulcrum 22e and the second fulcrum 26a and the vertical distance b between the first fulcrum 22e and the second fulcrum 26a are respectively And represented by the following formulas (1) and (2).

a = 1 × cos θ (1)
b = 1 × sin θ (2)
l: Distance between the first fulcrum 22e and the second fulcrum 26a
a: Horizontal distance between the first fulcrum 22e and the second fulcrum 26a
b: Vertical distance between the first fulcrum 22e and the second fulcrum 26a
θ: angle θ of drag link 25 with respect to the horizontal plane

  As the first fulcrum 22e moves up and down, the drag link 25 connected to the first fulcrum 22e also swings, and the angle θ of the drag link 25 with respect to the horizontal plane also changes. When loaded, the angle θ with respect to the horizontal plane of the drag link 25 becomes smaller when loaded, so the horizontal direction between the first fulcrum 22e and the second fulcrum 26a is based on the above equations (1) and (2). As the distance a increases, the vertical distance b between the first fulcrum 22e and the second fulcrum 26a decreases.

  When loaded, the horizontal distance a between the first fulcrum 22e and the second fulcrum 26a becomes longer (the vertical distance b becomes shorter) when loaded, so that when the drag link 25 swings, The pitman arm 26 that is rotationally connected to the drag link 25 at the fulcrum 26a also swings about the output shaft 34a, and the output shaft 34a rotates. Then, since the rotation of the output shaft 34a is transmitted to the steering shaft 32 via the power steering device 34, the steering shaft 32 (steering wheel 31) rotates. Thus, the steering shaft 32 rotates depending on whether or not the vehicle 100 has a cargo passenger.

  Therefore, as shown in FIG. 4A, a steering angle difference (hereinafter simply referred to as a difference between the steering angle (rotation angle) of the steering shaft 32 in the no-loading state and the steering angle of the steering shaft 32 in the loading state). It is found that there is a correlation in which the amount of depression of the steering wheel shaft 21 with respect to the unloaded state is substantially proportional to the difference in steering angle. Since the amount of depression of the steering wheel shaft 21 and the axial weight of the steering wheel shaft 21 are in a correlation that is substantially proportional, as shown in FIG. There is a correlation that is almost proportional to the axle load. Therefore, in the present embodiment, the steering sensor 33 detects the steering angle difference of the steering shaft 32, and the detected steering angle difference is calculated as follows, as shown in FIG. Is referred to mapping data so that the increase width of the steering wheel axle weight with respect to the increase width of the steering angle becomes larger as the steering angle becomes larger, so that the axle weight of the steering wheel axle 21 is estimated. Hereinafter, a method for estimating the steering wheel axle load will be described in detail using the flowcharts shown in FIGS. 5 and 6.

(Reference steering angle acquisition process)
First, the “reference steering angle acquisition process” executed by the brake control ECU 61 described above will be described with reference to the flowchart of FIG. When the vehicle 100 starts traveling, the brake control ECU 61 estimates the vehicle weight of the vehicle 100 in S101. As a method of estimating the vehicle weight of the vehicle 100, various well-known methods can be adopted. For example, the following equation (4) obtained by modifying the equation of motion as shown in the following equation (3) is used. By using it, the vehicle weight of the vehicle 100 can be estimated.

F = Ma (3)
M = F / a (4)
F: Energy applied to vehicle 100 (including both positive and negative)
M: Weight of vehicle 100
a: Acceleration of vehicle 100

  The brake control ECU 61 obtains the driving force of the engine (motor), which is positive energy F applied to the vehicle 100, from an engine control ECU (hybrid control ECU) (not shown) and calculates the acceleration a of the vehicle 100 from the acceleration sensor 63. The vehicle weight M of the vehicle 100 is estimated by acquiring and substituting the energy F and the acceleration a into the above equation (4). Alternatively, the brake control ECU 61 acquires the braking force by the brake devices Bfl, Bfr, Brl, and Brr, which is the negative energy F applied to the vehicle 100, and the negative energy F and the acceleration a are expressed by the above equation (4). By substituting, the vehicle weight M of the vehicle 100 may be estimated. When S101 ends, the program proceeds to S102.

  In S102, the brake control ECU 61 determines whether or not the vehicle 100 is unloaded based on the vehicle weight M of the vehicle 100 estimated in S101, and if it is determined that the vehicle 100 is unloaded ( (S102: YES), the program proceeds to S103, and if it is determined that the vehicle 100 is not unloaded (S102: NO), the program is returned to S101. The vehicle 100 being unloaded refers to a state in which no occupant other than the driver is on the vehicle 100 and cargo is not loaded. In the process of S102, the brake control ECU 61 determines whether or not the vehicle 100 is unloaded by determining whether or not the vehicle weight M of the vehicle 100 estimated in S101 is within a predetermined range. . In the present embodiment, the vehicle 100 is a large vehicle whose vehicle weight changes greatly depending on the passenger (for example, 2t to 10t or more). Therefore, the difference of about several tens of kg is slight in estimating the axle weight of the steering wheel shaft 21. is there.

  In S103, the brake control ECU 61 determines whether or not the vehicle 100 is traveling straight, and if it is determined that the vehicle 100 is traveling straight (S103: YES), the program proceeds to S104, and the vehicle 100 If it is determined that the vehicle is not traveling straight (S103: NO), the program is returned to S101. Note that the brake control ECU 61 determines that the vehicle 100 is traveling straight when the wheel speed difference obtained from the wheel speed sensors Sfl and Sfr is zero. Alternatively, the brake control ECU 61 determines that the vehicle 100 is traveling straight when the lateral acceleration obtained from the acceleration sensor 63 is zero. Note that it may be determined whether the vehicle 100 is traveling straight based on the yaw rate of the vehicle 100 detected by the yaw rate sensor 62.

  In S104, the brake control ECU 61 detects the steering angle (rotation angle) of the steering shaft 32 based on the detection signal from the steering sensor 33, and the steering angle is in a state where the vehicle 100 is not loaded and is traveling straight ahead. Is stored in the storage device of the brake control ECU 61, and the program returns to S101.

  As described above, the “reference steering angle” is acquired and stored in the reference steering angle acquisition process for the following reason. The large vehicle 100 often employs an axle suspension type suspension in which the steering wheel shaft 21 is suspended and supported by a leaf spring 41. In such a suspension, as described above, the leaf spring 41 ( The steering wheel shaft 21 may be displaced with respect to the vehicle 100). Even in such a case, by newly acquiring the “reference steering angle”, the shift of the “reference steering angle” due to the shift of the steering wheel shaft 21 with respect to the leaf spring 41 is prevented.

(Steering wheel axle weight estimation processing)
Next, the “steering wheel axle load estimation process” executed by the brake control ECU 61 described above will be described with reference to the flowchart of FIG. When the vehicle 100 starts running, in S201, the brake control ECU 61 estimates the vehicle weight of the vehicle 100 and advances the program to S202. The method for estimating the vehicle weight of the vehicle 100 is the same as the process of S101 shown in FIG.

  In S202, based on the vehicle weight M of the vehicle 100 estimated in S201, it is determined whether or not the vehicle 100 is in a loaded state. If it is determined that the vehicle 100 is in a loaded state (S202: YES), The program proceeds to S203, and when it is determined that the vehicle 100 is not in a loaded state (S202: NO), the program is returned to S201.

  In S203, the brake control ECU 61 determines whether or not the vehicle 100 is traveling straight, and if it is determined that the vehicle 100 is traveling straight (S203: YES), the program proceeds to S204, and the vehicle 100 If it is determined that the vehicle is not traveling straight (S203: NO), the program is returned to S201. Note that the method for determining whether or not the vehicle 100 is traveling straight is the same as the process of S103 shown in FIG.

  In S204, the brake control ECU 61 detects the steering angle (rotation angle) of the steering shaft 32 based on the detection signal from the steering sensor 33, and the steering angle is a state in which the vehicle 100 is in a loaded state and is traveling straight ahead. Is stored in the storage device of the brake control ECU 61 and the program proceeds to S205.

  In S205, the brake control ECU 61 is the difference between the “reference steering angle” stored in the storage unit of the brake control ECU 61 in the process of S104 shown in FIG. 5 and the “comparison steering angle” acquired in the process of S204. The axial weight of the steering wheel shaft 21 is estimated by referring to the “steering angle difference” in the mapping data shown in FIG. When S205 ends, the program returns to S201.

  Note that the axial weight of the rear wheel shaft 52 can be estimated from the axial weight of the steering wheel shaft 21 estimated in S205 and the vehicle weight of the vehicle 100 estimated in the processing of S201. Then, the brake control ECU 61 obtains the turning behavior of the vehicle 100 in consideration of the estimated axle weight of the steering wheel shaft 21 and the axle weight of the rear wheel shaft 52, and executes the above-described skid prevention control.

(Description of the effect of this embodiment)
As is apparent from the above description, the inventor has conducted research on the axle weight estimation device for a steered wheel. As a result, “in the vehicle 100 including the pitman arm 26 that swings in the vertical direction, It was found that there is a correlation with the steering angle. According to the above knowledge, when the axle weight of the steering wheel shaft 21 changes, the amount of depression with respect to the steering wheel shaft 21 changes, and the pitman arm 26 swings in the vertical direction. Change. Therefore, in a vehicle including the pitman arm 26 that swings in the vertical direction, it is possible to estimate the axial weight of the steering wheel shaft 21 based on the steering angle. For this reason, if the vehicle 100 is equipped with the steering sensor 33 (steering angle detection unit) for detecting the steering angle, it is possible to estimate the axle weight of the steering wheel shaft 21 only by adding a program. Instead, the axial weight of the steering wheel shaft 21 can be estimated.

  In addition, in the process of S203 of FIG. 6, when the brake control ECU 61 (straight-running state determination unit) determines that the vehicle 100 is traveling straight, the brake control ECU 61 (steering wheel axle load estimation unit) is acquired in S204. Based on the steering angle when the vehicle 100 is traveling straight, the axle weight of the steering wheel shaft 21 is estimated. More specifically, the above knowledge is that “the steering angle is an angle changed by an amount corresponding to the axial weight of the steering wheel shaft 21 based on the steering angle corresponding to the turning angle of the steering wheels Wfl, Wfr”. is there. Further, the detection of the straight traveling state of the vehicle 100 can be detected more reliably than the detection of the predetermined turning state of the vehicle 100. Thus, since the steering angle is detected in the straight traveling state that can be reliably detected, the steering angle in the straight traveling state, that is, the turning angle of the steered wheels Wfl and Wfr is substantially 0, can be detected more reliably. Then, by estimating the axle weight of the steering wheel shaft 21 based on the steering angle when the turning angle of the steered wheels Wfl, Wfr is substantially 0, the axle weight of the steering wheel shaft 21 can be estimated more reliably. Further, since the frequency with which the vehicle 100 is traveling straight is higher than the frequency with which the vehicle 100 is turning, the axle load of the steering wheel shaft 21 can be estimated more frequently and more reliably.

  When it is determined in S102 of FIG. 5 that the vehicle 100 is unloaded, the brake control ECU 61 acquires the “reference steering angle” in S104, and in S205, the brake control ECU 61 sets “reference steering”. Based on the “angle” and the “comparison steering angle”, the axial weight of the steering wheel shaft 21 is estimated. Since the axle weight of the steering wheel shaft 21 when the vehicle 100 is not loaded is known in advance from the design value, the axle weight of the steering wheel shaft 21 can be reliably estimated.

  As shown in FIG. 4 (B), the inventor stated that “the correlation between the steering angle difference and the steering wheel axle weight is such that the greater the steering angle difference, the greater the increase in the steering wheel axle weight relative to the increase in the steering angle difference. I got the knowledge that it will grow. Therefore, in the process of S205 in FIG. 6 described above, by estimating the axle load of the steering wheel axle 21 based on the mapping data (shown in FIG. 4B, steering wheel axle weight information) and the steering angle difference, the steering wheel axle 21 The axle load is estimated with high accuracy.

  In the embodiment described above, the “steering wheel axle weight” is calculated using mapping data representing the relationship between the “steering angle difference” and the “steering wheel axle weight” as shown in FIG. However, the “steering wheel axle load” may be calculated using an arithmetic expression representing the relationship between the “steering angle difference” and the operating wheel axle weight.

  In the embodiment described above, a “steering angle difference” that is a difference between the “reference steering angle” and the “comparative steering angle” is calculated, and the “steering angle difference” is calculated as “steering angle difference” and “steering wheel shaft”. The axial weight of the steering wheel shaft 21 is estimated by referring to the mapping data (shown in FIG. 4B) representing the relationship with the “heavy”. However, when the vehicle 100 is traveling straight, the steering angle of the steering wheel 31 detected by the steering sensor 33 is referred to mapping data representing the relationship between the “steering angle” and the “steering wheel axle weight”, whereby the steering wheel axle It is possible to estimate the axial weight of 21.

  In the embodiment described above, the “reference steering angle”, which is the steering angle of the steering wheel 31 detected by the steering sensor 33 when there is no load, is detected to estimate the axial weight of the steering wheel shaft 21. However, not only when the vehicle is not loaded, the “reference steering angle”, which is the steering angle of the steering wheel 31 detected by the steering sensor 33 when the vehicle 100 is at a predetermined weight, is detected, and the axle weight of the steering wheel shaft 21 is increased. There is no problem even if it is estimated. Even in this embodiment, when the vehicle is at a predetermined vehicle weight, the reference “steering angle” is newly detected, so that the axial weight of the steering wheel shaft 21 can be estimated with high accuracy. In other words, by evaluating the “comparative steering angle” based on the “reference steering angle” in a predetermined vehicle weight state, the axial weight of the steering wheel shaft 21 can be estimated with higher accuracy.

  In the embodiment described above, the “reference steering angle” and the “comparison steering angle” are detected when the vehicle 100 goes straight, and the axle weight of the steering wheel shaft 21 is determined from these “reference steering angle” and “comparison steering angle”. Is estimated. However, when the vehicle 100 is in a predetermined turning state, that is, when the steering wheels Wfl and Wfr are at a predetermined turning angle, the “reference steering angle” and the “comparison steering angle” are detected, and these “reference steering angles” are detected. ”And“ comparison steering angle ”, the axle weight of the steering wheel shaft 21 may be estimated. Note that detection of the vehicle 100 in a predetermined turning state is detected by the wheel speed sensors Sfl, Sfr, Srl, Srr, the yaw rate sensor 62, and the acceleration sensor 63, and the brake control ECU 61 is based on signals detected by these sensors. Thus, it is determined whether or not the vehicle 100 is in a predetermined turning state. In the case of this embodiment, even if the vehicle 100 is turning, the axial weight of the steering wheel shaft 21 can be estimated.

  In the embodiment described above, the steering angle detection unit that detects the steering angle of the steering wheel 31 is the steering sensor 33 that detects the steering angle of the steering shaft 32, but the steering angle detection provided in the power steering device 34 and the like. It does not matter even if it is a part.

  The suspension of the vehicle 100 according to the embodiment described above is an axle suspension type, but it goes without saying that the technical idea of the present invention can also be applied to a vehicle equipped with an independent suspension.

  DESCRIPTION OF SYMBOLS 21 ... Steering wheel shaft, 26 ... Pitman arm, 31 ... Steering wheel, 33 ... Steering sensor (steering angle detection part), 61 ... Brake control ECU (Vehicle weight state determination part, straight travel determination part, turning state detection part, memory | storage part) 62 ... Yaw rate sensor (turning state detection unit) 63 ... Acceleration sensor (turning state detection unit) 100 ... Vehicle, Sfl, Sfr, Srl, Srr ... Wheel speed sensor (turning state detection unit)

Claims (4)

A steering wheel axle load estimation device for a vehicle having a pitman arm that transmits an operation force of a steering wheel to a steering wheel and swings in a vertical direction,
A steering angle detector for detecting a steering angle of the steering wheel;
A steering wheel axle load estimation unit that estimates the steering wheel axle load based on the steering angle detected by the steering angle detector;
Have a, and determining vehicle weight state determination unit to vehicle weight state of the vehicle,
The steering angle detection unit uses the vehicle steering state determination unit as a reference steering angle when the vehicle weight determination unit determines that the vehicle weight is in a predetermined vehicle weight state. Detecting the steering angle as a comparative steering angle when it is determined that the vehicle is in a vehicle weight state other than the predetermined vehicle weight state;
The steering wheel axle weight estimation unit estimates the steering wheel axle weight when the steering angle detector detects the comparison steering angle based on a steering angle difference between the reference steering angle and the comparative steering angle. Heavy estimation device. In claim 1,
A straight-running state determination unit that determines whether or not the vehicle is traveling straight;
The steering angle detection unit determines that the vehicle weight is determined to be a predetermined vehicle weight state by the vehicle weight state determination unit and that the vehicle is traveling straight by the straight-ahead state determination unit. When the vehicle weight state determining unit determines that the vehicle is in a vehicle weight state other than the predetermined vehicle weight state using the steering angle detected when the vehicle is being operated as a reference steering angle, and by the straight traveling state determining unit A steering wheel axle load estimation device that detects the steering angle detected when it is determined that the vehicle is traveling straight as a comparative steering angle . 3. The steering wheel axle load estimation device according to claim 1 or 2, wherein the steering angle detection unit detects the reference steering angle when the vehicle is in an unloaded state . In any one of Claims 1 thru | or 3,
Storage that stores the steering wheel axle weight information that correlates the steering angle difference and the steering wheel axle weight such that the larger the steering angle difference is, the greater the increment of the steering wheel axle weight with respect to the increment of the steering angle difference is. Further comprising
The steering wheel axle weight estimation unit is a steering wheel axle weight estimation device that estimates the steering wheel axle weight based on the steering wheel axle weight information and the steering angle .

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