JP2009269559A - Method and apparatus for estimating vehicle weight and vehicle traveling control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and accurately estimate the vehicle weight of a vehicle irrespective of the inclination of the road surface on which the vehicle is traveling. <P>SOLUTION: While the vehicle travels through inertia at a set speed and more (the determination of S1, S2 is YES) and in linear motion on the normal road (the determination of S3, S4 is YES), an acceleration sensor detects (S5) the deceleration rate of the vehicle's fore-and-aft direction, and estimates, at a plurality of stages, the vehicle weight of the vehicle, based on the deceleration rate detected (S6 to S10). Thus, the vehicle weight can be accurately estimated irrespective of the inclination of the road surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to estimation of vehicle weight, road surface determination using the estimated vehicle weight, and vehicle travel control according to the determined type of road surface.

  One estimation method of vehicle weight is described in Patent Document 1 below. This estimation method acquires engine torque and acceleration during vehicle acceleration and acceleration (deceleration) during inertial running, and estimates vehicle weight based on both acceleration and engine torque. Further, the following Patent Documents 2 and 3 describe the determination of the road surface on which the vehicle is traveling. The one described in Patent Document 2 determines that the road surface is sandy when both the longitudinal acceleration of the vehicle body and the rotational acceleration of the wheel are below the expected acceleration calculated based on the driving force of the engine. The one described in Patent Document 3 is the road surface estimated by the road surface friction state estimation unit when the road surface state newly measured by the road surface state measurement unit is the same as the reference road surface state. By updating to the friction state, the reference friction state is updated according to changes in the vehicle characteristics, and then, based on the road surface friction state newly estimated by the road surface friction state estimation means and the updated reference road surface friction state The road surface state in which the vehicle is currently traveling is determined.

On the other hand, Patent Document 4 describes that in anti-skid control, when the road surface on which the vehicle is traveling is sandy, the slip amount at the start of pressure increase of the brake cylinder is different from that on a normal road. In Patent Document 5, the anti-skid control device has a means for determining whether or not the traveling path of the vehicle is sandy, and when it is determined that the vehicle is sandy, the brake cylinder hydraulic pressure corresponding to the sandy is determined. There is provided means for performing increase / decrease processing, and means for re-determining whether or not the road is sandy based on the braking state of the vehicle after the start of increase / decrease processing by the means, so It is described that the execution of skid control is suppressed.
JP 10-104049 A JP 2006-335114 A JP 2005-138839 A JP 2006-160202 A JP 2006-335111 A

  The present invention makes it possible to easily estimate the vehicle weight against the background described above, to be able to determine the road surface on which the vehicle is traveling in consideration of the vehicle weight, and to An object of the present invention is to make it possible to appropriately perform vehicle travel control in accordance with the type of road surface.

According to the present invention, when the vehicle is coasting on a road surface with known wheel rolling resistance, the longitudinal deceleration of the vehicle is detected by the acceleration sensor, and the detected deceleration which is the detected deceleration is detected. The vehicle weight estimation method for estimating the vehicle weight which is the weight of the vehicle based on the above is obtained.
Further, according to the present invention, (A) a rolling resistance acquisition unit that acquires rolling resistance of wheels on a road surface on which the vehicle is traveling, and (B) an inertial traveling detection unit that detects that the vehicle is traveling inertially, (C) an acceleration sensor that detects the longitudinal acceleration of the vehicle; and (D) the inertia running detection unit that the vehicle is coasting on the road surface on which the rolling resistance is acquired by the rolling resistance acquisition unit. A vehicle weight estimation unit including a vehicle weight estimation unit that estimates a vehicle weight that is the weight of the vehicle based on a detected deceleration that is a longitudinal deceleration detected by the acceleration sensor. Is obtained.
Further, (b) obtained on the predetermined standard road surface of the vehicle from the vehicle weight estimation device, (b) the vehicle weight estimated by the vehicle weight estimation device, and the output of the traveling drive source of the vehicle. And (c) the vehicle is running based on the expected acceleration estimated by the acceleration estimation unit and the detected acceleration that is the acceleration detected by the acceleration sensor. There is obtained a vehicle travel control device including a road surface discriminating unit that discriminates the road surface, and (d) a discrimination result using unit that uses the discrimination result of the road surface discriminating unit for the travel control of the vehicle.

According to the vehicle weight estimation method and the vehicle weight estimation device, the vehicle weight can be easily estimated.
If the air resistance is ignored, the deceleration while the vehicle is coasting has a one-to-one relationship with the vehicle's inertial mass, and thus the vehicle weight, as long as the road surface condition, i.e., the gradient and the rolling resistance of the wheel are the same. The deceleration becomes smaller as the vehicle weight increases. On the other hand, the detected deceleration, which is a deceleration detected by the acceleration sensor that detects the acceleration in the front-rear direction, is not affected by the road surface gradient. For example, the actual deceleration (deceleration in the direction parallel to the road surface), which is the actual deceleration when the vehicle is coasting on an uphill road, has the same wheel rolling resistance for vehicles with the same vehicle weight. The actual deceleration is naturally larger than that when coasting on a flat road, but the detected deceleration is the same. This is because the road gradient on the uphill road serves to reduce the deceleration detected by the acceleration sensor, and the road gradient on the downhill road serves to increase the detected deceleration. The detected deceleration at can be regarded as a detected deceleration on a flat road.
Therefore, if the deceleration is detected by the acceleration sensor and the vehicle weight is estimated based on the detected deceleration, it can be determined whether the road surface on which the vehicle is coasting is an uphill road, a downhill road, or a flat road. It is not necessary to make a problem, and it is always assumed that the vehicle is coasting on a flat road, and the vehicle weight can be estimated at any time to obtain an accurate vehicle weight. However, since the rolling resistance of the wheel is affected, it is necessary to acquire the rolling resistance in advance.
In the above description, air resistance is ignored (or assumed to be negligible), but if not ignored (or not negligible), strictly speaking, the wind direction and wind speed outside the vehicle are acquired. Then, it is necessary to acquire air resistance based on those acquired and to take into account when estimating the vehicle weight. However, when the vehicle traveling speed is equal to or higher than the set speed, the influence of the wind outside the vehicle may be ignored, and the vehicle weight may be estimated considering only the air resistance determined by the vehicle traveling speed.

  Further, according to the vehicle travel control device, the expected acceleration that can be expected to be obtained on the standard road surface is accurately calculated based on the vehicle weight estimated by the vehicle weight estimation device and the output of the travel drive source of the vehicle. The road surface on which the vehicle is traveling can be determined with high reliability based on the accurate expected acceleration and the detected acceleration detected by the acceleration sensor. Then, by using this highly reliable road surface discrimination result for vehicle travel control, vehicle travel control can be appropriately performed.

Aspects of the Invention

  In the following, the invention that is claimed to be claimable in the present application (hereinafter sometimes referred to as “claimable invention”. The claimable invention is at least the “present invention” to the invention described in the claims. Some aspects of the present invention, including subordinate concept inventions of the present invention, superordinate concepts of the present invention, and inventions of other concepts) will be exemplified and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is for the purpose of facilitating the understanding of the claimable invention, and is not intended to limit the combinations of the constituent elements constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, the prior art, and the like. The added aspect and the aspect in which the constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

  In each of the following terms, (1) corresponds to claim 1, (3) corresponds to claim 2, (6) corresponds to claim 3, (11) corresponds to claim 4, (12) corresponds to claim 5, (13) corresponds to claim 6, and (15) corresponds to claim 7.

(1) In a state where the vehicle is coasting on a road surface with known wheel rolling resistance, a longitudinal deceleration of the vehicle is detected by an acceleration sensor, and the detected deceleration which is the detected deceleration is detected. A vehicle weight estimation method for estimating a vehicle weight which is a weight of the vehicle based on the vehicle weight.
(2) In a state where the vehicle is coasting on a road surface determined in advance as a standard road surface, a deceleration in the front-rear direction of the vehicle is detected by an acceleration sensor, and the detected deceleration which is the detected deceleration is obtained. A vehicle weight estimation method for estimating a vehicle weight which is a weight of the vehicle based on the vehicle weight.
The rolling resistance of the wheel on the standard road surface can be obtained in advance by experiment or calculation. As long as the vehicle is coasting on the standard road surface, a constant value can be used as the rolling resistance of the wheel. It is desirable to determine the most common road surface in the area where the vehicle is used as the standard road surface. Generally, paved road surfaces such as dry asphalt roads and dry concrete road surfaces are suitable as standard road surfaces. In some cases, a dry unpaved road surface or a wet unpaved road surface may be defined as a standard road surface.
(3) a rolling resistance acquisition unit that acquires rolling resistance of wheels on the road surface on which the vehicle is traveling;
An inertia traveling detector for detecting that the vehicle is inertial traveling;
An acceleration sensor for detecting acceleration in the longitudinal direction of the vehicle;
The longitudinal deceleration detected by the acceleration sensor in a state where the inertia running detection unit detects that the vehicle is coasting on the road surface from which the rolling resistance is acquired by the rolling resistance acquisition unit. A vehicle weight estimation unit that estimates a vehicle weight that is the weight of the vehicle based on the detected deceleration.
(4) The vehicle weight estimation device according to (3), wherein the rolling resistance acquisition unit includes a detected road surface state dependence acquisition unit that acquires the rolling resistance based on a detection result of a road surface state by the road surface state detection device.
As the road surface state detection device, for example, an imaging device that images the road surface, an unevenness detection device that emits ultrasonic waves toward the road surface and detects road surface unevenness based on reflected waves, and emits light toward the road surface, A flatness detection device or the like that detects the flatness of the road surface based on the reflected light can be used. Alternatively, two or more of a plurality of devices such as the image pickup device, the unevenness detection device, and the flatness detection device can be used in combination.
(5) The vehicle weight estimation device according to (3) or (4), wherein the rolling resistance acquisition unit includes a navigation information dependence acquisition unit that acquires the rolling resistance based on information obtained from a navigation system.
When the navigation system can acquire information on whether the road surface on which the vehicle is currently traveling is one of multiple types of road surfaces, such as asphalt paved roads, concrete paved roads, and unpaved roads, Based on the information acquired by the navigation system, the type of road surface on which the vehicle is currently traveling can be determined. Therefore, if the rolling resistance of the wheel on each of the various road surfaces is acquired in advance by experiments or the like and stored in the rolling resistance memory of the vehicle weight estimation device, the rolling resistance can be easily acquired.
(6) The rolling resistance acquisition unit according to any one of (3) to (5), including a standard road surface detection unit that detects that the vehicle is traveling on a predetermined standard road surface. Vehicle weight estimation device.
If the standard road surface is determined in advance, the rolling resistance on the standard road surface is acquired by experiment or the like, and stored in the vehicle weight estimation device as at least one parameter for vehicle weight estimation, the rolling resistance acquisition unit is Rolling resistance can be acquired by including a standard road surface detection unit.
(7) The coasting detection unit detects a non-acceleration operation detection unit that detects that the acceleration operation member of the vehicle is in the original position, and a non-braking operation that detects that the braking operation member of the vehicle is in the original position. The vehicle weight according to any one of (3) to (6), wherein the vehicle weight is detected based on detection states of the non-acceleration operation detection unit and the non-braking operation detection unit. Estimating device.
When the acceleration operation member such as an accelerator pedal and the brake operation member such as a brake pedal are both released and are in the original position, the vehicle travels inertially. Therefore, it is reasonable that the inertial running detection unit includes a non-acceleration operation detection unit and a non-braking operation detection unit, and when both the detection units are in the detection state, the inertia running detection is detected. That is. In addition, the non-acceleration operation detection unit is already provided for the control of the vehicle drive device, and the non-braking operation detection unit is already used for the control of the vehicle brake system and the vehicle stability control. Since these are often provided, the vehicle weight estimation device can be configured at low cost by using them.
(8) The vehicle weight estimation unit includes a stage estimation unit that estimates to which stage the load weight area planned for the vehicle belongs is divided into a plurality of stages. Or the vehicle weight estimation apparatus according to any one of (7).
It is also possible for the vehicle weight estimation unit to estimate the vehicle weight with a continuous value. However, it is often sufficient that the vehicle weight for appropriately controlling the traveling of the vehicle belongs to which of a plurality of stages. For example, whether the vehicle belongs to the largest loading area (in a fixed volume state), belongs to an intermediate loading area (in a middle loading state), or belongs to the lightest loading area (in a light loading state) In many cases, the estimation may be divided into about three stages. Of course, it may be estimated in two stages or may be estimated in four or more stages.
(11) The vehicle weight estimation device according to any one of (1) to (8);
An acceleration estimator for estimating an expected acceleration expected to be obtained on a predetermined standard road surface of the vehicle from a vehicle weight estimated by the vehicle weight estimation device and an output of a traveling drive source of the vehicle;
A road surface discriminating unit that discriminates a road surface on which the vehicle is traveling based on an expected acceleration estimated by the acceleration estimation unit and a detected acceleration that is an acceleration detected by the acceleration sensor;
A vehicle travel control device comprising: a discrimination result utilization unit that utilizes the discrimination result of the road surface discrimination unit for travel control of the vehicle.
(12) The vehicle travel control device according to (11), wherein the road surface determination unit includes a sandy land traveling determination unit that determines whether or not the vehicle is traveling on sandy land.
Sandy roads have a high rolling resistance and a low coefficient of friction with the wheels, and therefore, vehicle travel control requires special consideration that differs from other road surfaces. According to the vehicle travel control device of this section, The effects of the invention can be enjoyed particularly effectively.
(13) A slip suppression control unit that prevents at least one of driving torque and braking torque for the vehicle wheel from being excessively controlled by controlling at least one of the driving torque and braking torque for the vehicle wheel; The vehicle travel control device according to (11) or (12), including a control parameter changing unit that changes a control parameter in the suppression control unit according to a road surface.
The slip suppression control unit suppresses at least one of a longitudinal slip of the wheel (slip in a plane perpendicular to the rotational axis of the wheel) and a lateral slip (slip in a direction parallel to the rotational axis of the wheel). be able to. The former slip includes, for example, a slip when the vehicle is braked and a slip when the vehicle is driven, and the latter includes, for example, a slip when the vehicle is turning. In any case, since the slip of the wheel is significantly affected by the state of the road surface, changing the control parameter according to the determination result of the road surface determination unit is effective in increasing the control accuracy.
(14) The control parameter changing unit sets a control start determination threshold value for determining that the at least one of the driving torque and the braking torque should be started in the slip suppression control unit. The vehicle travel control device according to item (13), including a control start determination threshold value changing unit that changes in accordance with the determination result.
The control start determination threshold value is particularly important among the control parameters that are affected by the road surface condition, and according to the vehicle travel control device of this section, the effects of the invention can be enjoyed particularly effectively.
(15) The slip suppression control unit includes an anti-skid control unit that prevents excessive slip in the front-rear direction of the wheel during braking of the vehicle, and the control start determination threshold value changing unit includes the anti-skid control unit. The vehicle travel control device according to (14), further including an anti-skid control start threshold value changing unit that changes the control start determination threshold value in the skid control unit according to the determination result of the road surface determination unit.
(21) an acceleration sensor for detecting acceleration in the longitudinal direction of the vehicle;
A slip suppression control unit that prevents an excessive slip of the wheel by controlling at least one of a driving torque and a braking torque for the wheel of the vehicle;
The expected acceleration in the front-rear direction expected to be obtained on the road surface defined as the standard road surface of the vehicle is estimated from at least the vehicle weight that is the weight of the vehicle and the drive source output that is the output of the drive source of the vehicle. A sandy road determination unit that determines whether the vehicle is running on sandy ground based on the estimated expected acceleration and a detected acceleration that is a longitudinal acceleration detected by the acceleration sensor;
A vehicle travel control device comprising: a determination result utilization unit that utilizes the determination result of the sandy travel determination unit for the control of the slip suppression control unit.
Also in this section, it is possible to estimate the vehicle weight in the same manner as in the vehicle weight estimation method and the vehicle weight estimation apparatus described in any one of (1) to (8). However, the present invention is not limited to this. For example, the vehicle weight is detected by a load sensor that detects the air pressure in the air spring, the hydraulic pressure in the shock absorber with a high-pressure accumulator, and the load applied to the suspension component. It is also possible to do so. Further, the determination result utilization unit may be any one of the items (13) to (15).
(22) The slip suppression control unit includes an anti-skid control unit that prevents an excessive slip in the front-rear direction of the wheel during braking of the vehicle, and the determination result utilization unit is provided in the anti-skid control unit An anti-skid control start threshold value for changing a control start determination threshold value for determining that the control of at least one of the driving torque and the braking torque should be started according to the determination result of the sandy land traveling determination unit The vehicle travel control device according to item (21), including a change unit.
(23) a rolling resistance acquisition unit that acquires rolling resistance of wheels on the road surface on which the vehicle is traveling;
An inertia traveling detector for detecting that the vehicle is inertial traveling;
An acceleration sensor for detecting acceleration in the longitudinal direction of the vehicle;
The longitudinal deceleration detected by the acceleration sensor in the state where the inertia running detector detects that the vehicle is running on the road surface on which the rolling resistance is acquired by the rolling resistance acquisition unit. A vehicle weight estimation unit that estimates a vehicle weight that is a weight of the vehicle based on the detected deceleration, and the sandy road determination unit estimates the estimated acceleration by the vehicle weight estimation unit. The vehicle travel control apparatus according to item (21) or (22), wherein vehicle weight is used as the vehicle weight.

Hereinafter, a hydraulic brake system as a kind of vehicle control device according to the present invention will be described in detail with reference to the drawings.
Reference numeral 10 represents a brake pedal, reference numeral 12 represents a master cylinder, reference numerals 20 and 22 represent brake cylinders for the left and right front wheels FL and FR, brake brakes 24 and 26, and reference numerals 30 and 32 represent brakes for the left and right rear wheels RL and RR. 34 and 36 brake cylinders are shown. In this embodiment, both the left and right front wheel brakes 24 and 26 and the left and right rear wheel brakes 34 and 36 are hydraulic brakes, but the left and right front wheel brakes 24 and 26 are disc brakes and the left and right rear wheel brakes 34. 36 are drum brakes. The vehicle of this embodiment is a four-wheel drive vehicle, and all of the left and right front wheels FL and FR and the left and right rear wheels RL and RR are driven.
The master cylinder 12 is of a tandem type and includes two pressure pistons. The front of each of the two pressure pistons is a pressure chamber. One of the two pressure pistons is linked to the brake pedal 10 via a vacuum booster 38. The left and right front wheel brake cylinders 20 and 22 are connected to one of the two pressurizing chambers, and the left and right rear wheel brake cylinders 30 and 32 are connected to the other. In this embodiment, there are two front and rear systems, the hydraulic pressures of the left and right front wheel brake cylinders 20 and 22 can be controlled separately, and the left and right rear wheel brake cylinders 30 and 32 are controlled in common. The

Holding valves 44 and 46 are respectively provided between the one pressurizing chamber and the left and right front wheel brake cylinders 20 and 22, and pressure reducing valves 50 and 52 are respectively provided between the brake cylinders 20 and 22 and the reservoir 48. Provided. The holding valves 44 and 46 are normally open electromagnetic open / close valves that are opened and closed by controlling the current supplied to the solenoid, and the pressure reducing valves 50 and 52 are normally closed electromagnetic open / closed that are opened and closed by controlling the current supplied to the solenoid. It is a valve. In addition, check valves 54 and 56 are provided in parallel with the holding valves 44 and 46, respectively. The check valves 54 and 56 allow the flow of hydraulic fluid from the brake cylinders 20 and 22 toward the master cylinder 12 and prevent the reverse flow.
A pump passage 58 extends from the reservoir 48 and is connected to the upstream side (master cylinder side) of the holding valves 44 and 46 between the pressurizing chamber of the master cylinder 12 and the brake cylinders 20 and 22 of the left and right front wheels. . A pump 60 and check valves 62 and 64 are provided in the pump passage 58. The hydraulic fluid in the reservoir 48 is pumped up by the pump 60 and returned to the master cylinder 12. The pump 60 is driven by an electric motor 66.
The hydraulic pressure in the left front wheel brake cylinder 20 is controlled by opening and closing the holding valve 44 and the pressure reducing valve 50, and the hydraulic pressure in the right front wheel brake cylinder 22 is controlled by opening and closing the holding valve 46 and the pressure reducing valve 52. The hydraulic pressures of the brake cylinders 20 and 22 are controlled independently.

Between the other pressurizing chamber and the brake cylinders 30 and 32 for the left and right rear wheels, a holding valve 70 and an LSP & BV (LSP Sensing Proportioning Bypath Valve) 72 are provided, and the brake cylinders 30 and 32 and the reservoir 74 are provided. Between the two, a pressure reducing valve 76 is provided. The LSP & BV72 is a valve that can change the breakpoint hydraulic pressure of the proportioning valve according to the ground load of the rear wheel. When the front wheel system fails, the hydraulic pressure of the master cylinder 12 is not reduced and the brake of the rear wheel is braked. It is transmitted to the cylinders 30 and 32. The holding valve 70 is a normally open electromagnetic open / close valve, and the pressure reducing valve 76 is a normally closed electromagnetic open / close valve. A check valve 78 is provided in parallel with the holding valve 70. The reservoir 74 and the upstream side of the holding valve 70 between the pressurizing chamber and the brake cylinders 30 and 32 are connected by a pump passage 80, and a pump 82 and check valves 84 and 86 are provided in the pump passage 80. The pump 82 is driven by an electric motor 88.
The hydraulic pressures of the brake cylinders 30 and 32 for the left and right rear wheels are commonly controlled by opening and closing the holding valve 70 and the pressure reducing valve 76.

Each of the electromagnetic on-off valves 44, 46, 50, 52, 70, 76 and the electric motors 66, 88 are controlled based on a command from the skid controller 100. The skid controller 100 mainly includes a computer including an execution unit 102, a storage unit 104, an input / output unit 106, and the like. The input / output unit 106 includes a wheel speed sensor 110 provided on each of the left and right wheels. 112, 114, 116, an acceleration sensor 118 for detecting the longitudinal acceleration (deceleration) of the vehicle, a brake switch 120 for detecting that the brake pedal 10 is operated, and detecting that an accelerator pedal (not shown) is operated. The accelerator switch 122, the turning state acquisition device 126, and the like are connected, and the above-described electromagnetic on-off valves and the electric motor are connected via a drive circuit (not shown).
The acceleration sensor 118 is a weight type that detects acceleration using the inertial mass of the weight, and the turning state acquisition device 126 includes a yaw rate sensor, a lateral G sensor, and the like, and at least whether or not the vehicle is in a turning state. Get the turning state including.

  An engine controller 130, a transmission controller 132, and a navigation system 134 are further connected to the input / output unit 106 of the skid controller 100. The engine controller 130 is configured mainly by a computer, and controls an engine that is a driving source of the vehicle, and supplies at least engine output information to the skid controller 100. The transmission controller 132 is also composed mainly of a computer and controls the transmission, and supplies at least information regarding the switching state of the transmission to the skid controller 100. The navigation system 134 notifies the driver of information on the position of the vehicle on the map and the driving environment, and the information on the driving environment includes at least information on whether or not the driving road surface is a normal road.

The storage unit 104 of the skid controller 100 stores a vehicle weight estimation program represented by the flowchart of FIG. 3, a road surface discrimination program represented by the flowchart of FIG. 4, an antilock control program represented by the flowchart of FIG. Has been. These programs are repeatedly executed while the vehicle key switch is ON.
Hereinafter, the operation of the hydraulic brake system will be described based on each flowchart.

First, estimation of vehicle weight will be described.
In S1 of the vehicle weight estimation program of FIG. 3, it is determined whether or not the vehicle speed V is equal to or higher than the set vehicle speed V1. The vehicle speed V is obtained by integration of a normal road coefficient or a normal road coefficient set for the normal road and the sand road, respectively, multiplied by the longitudinal acceleration detected by the acceleration sensor 118, and the wheel speed sensors 110 to 116. Also acquired based on the rotational speeds of the left and right front wheels FL, FR and the left and right rear wheels RL, RR detected by the above. The former is used during acceleration and deceleration of the vehicle, and is corrected by comparison with the latter during constant speed travel.

  If the determination result in S1 is NO, S2 and subsequent steps are skipped and one execution of this program ends. If YES, it is determined in S2 whether or not the vehicle is coasting. This determination is made based on signals from the brake switch 120 and the accelerator switch 122 whether or not both the brake pedal and the accelerator pedal are released and are in their original positions. If the determination result is YES, it is determined in S3 whether or not the vehicle is traveling straight on the basis of information from the turning state acquisition device 126. This is because an accurate longitudinal acceleration cannot be obtained during turning of the vehicle, which may not be suitable for estimation of the vehicle weight. If the determination result in S <b> 3 is YES, whether or not the vehicle is traveling on a normal road surface is determined based on information from the navigation system 134.

  If the determination result in S4 is YES, a signal from the acceleration sensor 118 is read in S5, and a signal obtained by inverting the sign is acquired as the deceleration -α. The obtained deceleration -α is compared with the threshold decelerations β1 and β2 in S6 and S7. β1 and β2 are both positive values, and β2> β1. Since the deceleration when the vehicle is coasting is smaller as the inertial mass is larger, when the detected deceleration -α is equal to or less than the set deceleration β1, it is determined that the vehicle is in a fixed volume state, and in S8 The fixed product flag is turned on, and the intermediate product flag and the light product flag are turned off. Similarly, in S9 and S10, the medium product or light product flag is turned on, and the other flags are turned off. In the present embodiment, the vehicle weight is estimated as to which stage the load weight area planned for the vehicle is divided into three stages.

Next, road surface discrimination will be described.
In S11 of the road surface discrimination program of FIG. 4, an engine output is acquired based on information from the engine controller 130. In S12, whether or not the vehicle is accelerating depending on whether or not the output is equal to or higher than the set output. Is determined. If the determination result in S12 is NO, S13 and subsequent steps are skipped and one execution of this program ends. If the determination result is YES, in S13, based on the information from the transmission controller 132, the transmission The switching state is acquired, and in S14, it is determined by execution of the vehicle weight estimation program whether the constant product flag, the middle product flag, or the light product flag is ON, and is determined in advance corresponding to each flag. The vehicle weight corresponding to the ON flag is read out from the constant product, medium product, and light product vehicle weights.

  Thereafter, in S15, information on the engine output and the transmission switching state is acquired from the engine controller 130 and the transmission controller 132, and the expected expression that can be expected at that point on a normal road based on these and the arithmetic expression stored in advance. The acceleration α1 is calculated. Subsequently, in S16, the detected acceleration α2 is read from the acceleration sensor 118. In S17 and S18, the vehicle travels by comparing the difference α1−α2 between the expected acceleration α1 and the detected acceleration α2 with the threshold acceleration differences δ1 and δ2. It is determined whether the road surface inside is a normal road, a bad road, or sand. For the same engine output, the actual acceleration obtained is the largest on the normal road, the second largest on the bad road, and the smallest sand, so the comparison between the acceleration difference α1-α2 and the threshold acceleration differences δ1, δ2 The type of road surface on which the vehicle is traveling can be determined. Depending on the result of the determination, the normal road flag, the bad road flag, and the sand flag are turned ON and the other flags are turned OFF in S19, S20, and S21, respectively, and one execution of the road surface determination program is completed.

  Depending on whether the road surface on which the vehicle is running is a normal road, a bad road, or sandy ground, vehicle stability control mainly for suppressing the destabilization of the running trajectory caused by the side slip of the wheel, the wheel at the time of driving the vehicle Various types of vehicle such as traction control for suppressing deterioration in acceleration performance caused by sliding in the longitudinal direction of the vehicle, anti-skid control for suppressing reduction in deceleration performance caused by sliding in the longitudinal direction of the wheel during braking of the vehicle, etc. The travel control is preferably changed, and the normal road flag, the bad road flag, and the sand flag are used for the travel control. An example of usage in anti-skid control will be described below.

Normally, the electromagnetic on-off valve is in the original position shown in FIG. The holding valves 44, 46, and 70 are in an open state, and the pressure reducing valves 50, 52, and 76 are in a closed state.
When the brake pedal 10 is operated, a hydraulic pressure corresponding to the operating force is generated in the pressurizing chamber of the master cylinder 12. This hydraulic pressure is supplied to the left and right front wheel brake cylinders 20 and 22, and the left and right rear wheel brake cylinders 30 and 32, and the left and right front wheel hydraulic brakes 24 and 26 and the left and right rear wheel hydraulic brakes 34 and 36 are operated. Be made.

  At this time, in the anti-skid control program of FIG. 5, it is determined in S31 and S32 whether or not either the sand flag or the rough road flag is ON, and the subsequent anti-skid is determined based on the determination result. The control parameter of the control is changed. For example, if the sand flag is set to ON, in S33, the hydraulic control start determination threshold value of the brake cylinders 20, 22, 30, 32 for suppressing the wheel slip from being excessive during vehicle braking is set. Including control parameters are set to values for sand control. Thereafter, in S34, a slip ratio (which can be set as a slip amount) is calculated based on the vehicle speed V and the rotation speed of each wheel, and the slip ratio is compared with a hydraulic pressure control start determination threshold value in S35. It is determined whether or not the hydraulic pressure control including that to be started should be started. If the determination result is NO, one execution of this program ends. If YES, the sand antiskid control in S36 is executed.

  In this control, when the vehicle is traveling straight, the hydraulic pressure of the brake cylinder is controlled so that the slip ratio of each wheel is substantially maximized in the longitudinal frictional force between the wheel and the road surface, and the vehicle turns. If the vehicle is in the middle, the hydraulic pressure of the brake cylinder is controlled so that the vehicle can be decelerated at the greatest possible deceleration while preventing the lateral slip between the wheels and the road surface from becoming excessive. Specifically, for example, if the slip ratio of the left front wheel FL is equal to or higher than the hydraulic pressure control start determination threshold as shown in FIG. 2, the holding valve 44 is closed, while the pressure reducing valve 50 is opened. The brake cylinder 20 is rapidly depressurized, and then the current supply to the pressure reducing valve 50 is repeatedly performed for a short time, whereby the brake cylinder 20 is slowly depressurized and the pressure reducing valve 50 is closed. The left front wheel FL waits for the rotation to recover. When the rotation of the left front wheel FL is restored to a predetermined state, the pressure reducing valve 50 is closed, the current supply to the holding valve 44 is repeated for a short time, and the brake cylinder 20 is slowly increased in pressure. If the slip ratio is greater than or equal to a set value smaller than the hydraulic pressure control start determination threshold, the brake cylinder 20 is depressurized again. This hydraulic pressure control is repeated until an anti-skid control end condition is satisfied, such as a decrease in the vehicle speed to a set vehicle speed or less, release of the brake pedal 10, etc. If the end condition is satisfied, the determination result in S37 becomes YES. Anti-skid control is terminated.

  If the rough road flag is set to ON and the determination result in S32 is YES, the control parameter including the hydraulic pressure control start determination threshold is set to a value for rough road control in S38, and S39 to In S42, rough road anti-skid control is performed. If the determination result in S32 is NO, the normal road control in S43 to S46 is performed. Since these controls are the same as the sandy anti-skid control except that the control parameters are different, description thereof will be omitted.

  As is clear from the above description, in this embodiment, the part of the skid controller 100 that executes S4 in the flowchart of FIG. 3 acquires the rolling resistance acquisition unit that acquires the rolling resistance of the wheels on the road surface on which the vehicle is traveling. The standard road surface detection part as an example is comprised. Further, the part that executes S2 and the brake switch 120 and the accelerator switch 122 constitute an inertia running detector that detects that the vehicle is coasting, and the part that executes S5 to S10 serves as the vehicle weight estimating part. It is composed. Further, the portion of the skid controller 100 that executes S11 to S15 in the program of FIG. 4 constitutes an acceleration estimation unit that estimates expected acceleration expected to be obtained on a predetermined standard road surface of the vehicle, and S16 Or the part which performs S21 comprises the road surface discrimination | determination part which discriminate | determines the road surface where the vehicle is drive | working based on an expected acceleration and a detected acceleration, The part which performs S18 is a vehicle running on sandy ground It constitutes a sandy land traveling determination unit that determines whether or not there is. Further, the part of the skid controller 100 that performs the anti-skid control shown in the flowchart of FIG. 5 constitutes an anti-skid control unit as an example of the slip suppression control unit, and the part that executes S31 to S33, S38, and S43. And a control parameter changing unit as an example of a discrimination result using unit that uses the discrimination result of the road surface discriminating unit for vehicle travel control. The control parameter changing unit includes an anti-skid control start threshold value changing unit. It is out.

  Although one embodiment of the claimable invention has been described in detail above, this is merely an example, and various embodiments are possible based on the knowledge of those skilled in the art, including the aspect described in the above [Aspect of the Invention] section. It can implement in the aspect which gave this change.

1 is a cross-sectional front view of a hydraulic brake system that includes an embodiment of the claimable invention and is itself an embodiment of the claimable invention. FIG. It is a graph for demonstrating the anti-skid control in the said hydraulic brake system. It is a flowchart showing the vehicle weight estimation program implemented in the skid controller shown in FIG. It is a flowchart showing the road surface discrimination | determination program implemented in the skid controller shown in FIG. It is a flowchart showing the anti-skid control program implemented in the skid controller shown in FIG.

Explanation of symbols

10: Brake pedal 12: Master cylinder FL, FR: Left and right front wheel RL, RR: Left and right rear wheel 20, 22: Brake cylinder (front wheel) 24, 26: Brake (front wheel) 30, 32: Brake cylinder (rear wheel) 34. 36: Brake (rear wheel) 38: Vacuum booster 44, 46: Holding valve 48: Reservoir 50, 52: Pressure reducing valve 54, 56: Check valve 58: Pump passage 60: Pump 62.64: Check valve 66: Electric Motor 70: Holding valve 72: LSP & BV 76: Pressure reducing valve 78: Check valve 80: Pump passage 82: Pump 84, 86: Check valve 88: Electric motor

Claims (7)

  In a state where the vehicle is coasting on a road surface with known wheel rolling resistance, the vehicle's longitudinal deceleration is detected by an acceleration sensor, and the vehicle is based on the detected deceleration that is the detected deceleration. A vehicle weight estimation method for estimating a vehicle weight which is a weight of a vehicle. A rolling resistance acquisition unit for acquiring rolling resistance of wheels on the road surface on which the vehicle is traveling;
An inertia traveling detector for detecting that the vehicle is inertial traveling;
An acceleration sensor for detecting acceleration in the longitudinal direction of the vehicle;
The longitudinal deceleration detected by the acceleration sensor in a state where the inertia running detection unit detects that the vehicle is coasting on the road surface from which the rolling resistance is acquired by the rolling resistance acquisition unit. A vehicle weight estimation unit that estimates a vehicle weight that is the weight of the vehicle based on the detected deceleration.   The vehicle weight estimation device according to claim 2, wherein the rolling resistance acquisition unit includes a standard road surface detection unit that detects that the vehicle is traveling on a predetermined standard road surface. The vehicle weight estimation device according to claim 2 or 3,
An acceleration estimator for estimating an expected acceleration expected to be obtained on a predetermined standard road surface of the vehicle from a vehicle weight estimated by the vehicle weight estimation device and an output of a traveling drive source of the vehicle;
A road surface discriminating unit that discriminates a road surface on which the vehicle is traveling based on an expected acceleration estimated by the acceleration estimation unit and a detected acceleration that is an acceleration detected by the acceleration sensor;
A vehicle travel control device comprising: a discrimination result utilization unit that utilizes the discrimination result of the road surface discrimination unit for travel control of the vehicle.   The vehicle travel control device according to claim 4, wherein the road surface determination unit includes a sandy land traveling determination unit that determines whether or not the vehicle is traveling on sandy land.   A slip suppression control unit that prevents at least one of a driving torque and a braking torque with respect to a wheel of the vehicle from preventing an excessive slip of the wheel, and the determination result utilization unit includes the slip suppression control unit The vehicle travel control device according to claim 4, further comprising a control parameter changing unit that changes the control parameter in accordance with the road surface.   The slip suppression control unit includes an anti-skid control unit that prevents excessive slip in the front-rear direction of the wheel during braking of the vehicle, and the control parameter changing unit includes the braking torque in the anti-skid control unit. The vehicle travel according to claim 6, further comprising: an anti-skid control start threshold value changing unit that changes a control start determination threshold value for determining that the control of the vehicle should be started according to a determination result of the road surface determination unit. Control device.

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