JP2007147493A - On-vehicle type inclination sensor and inclination detecting method for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an on-vehicle type inclination sensor and an inclination detecting method for a vehicle, capable of enhancing detection precision of an inclination angle. <P>SOLUTION: In this on-vehicle type inclination sensor 10 provided with detecting elements 12L, 12R having an intrinsic detecting direction, and capable of detecting an inclination of the vehicle 30, based on detection signals output therefrom, the inclination sensor 10 is mounted on a substrate 11 to make a detecting direction GR of the detecting element 12R and a detecting direction Gl of the detecting element 12L form respectively 45° of angle with respect to the center axis A-A of the vehicle 30, when the inclination sensor 10 is mounted on the vehicle 30. The detection precision of the inclination angle in the vehicle 30 is enhanced since a longitudinal (F, B)-directional inclination of the vehicle 30 or a width (L, R)-directional inclination of the vehicle 30 is thereby detected all the time by the two detecting elements 12L, 12R. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle-mounted tilt sensor that detects the tilt of a vehicle and a vehicle tilt detection method.

  As a conventional vehicle-mounted tilt sensor, like the tilt sensor described in Patent Document 1, a detection element capable of detecting a tilt tilted in the front-rear direction or the width direction of the vehicle is provided in the vehicle, thereby tilting the vehicle. An inclination sensor for detecting the above is known.

  For example, the conventional inclination sensor is provided with two detection elements (not shown) for detecting the inclination of the vehicle. As shown in FIGS. 7A and 7B, detection of one of the detection elements is performed. The tilt sensor 110 is arranged such that the direction GF is the front-rear (F, B) direction of the vehicle 130 and the detection direction GW of the other detection element is the width (L, R) direction of the vehicle 130. Here, the directions of arrows F, B, L, and R in FIG. 7A are respectively the front (F), rear (B), left (L), and right (R) directions of the vehicle 130. Equivalent to. An acceleration detection element is used as the detection element.

  In order to detect the inclination of the vehicle 130 in the parking state using such a detection element, for example, as shown in FIG. 7B, the vehicle 130 is moved forward and backward (F, B) during a normal period in the parking state. The average value of the acceleration in the direction is recorded as the reference value GFi, and the average value of the acceleration in the vehicle width (L, R) direction is recorded as the reference value GWi during the same period. Then, the inclination angle of the vehicle 130 is detected based on the difference between the acceleration GF1 in the front-rear (F, B) direction and the acceleration GW1 in the width (L, R) direction and the reference values GFi, GWi, which are measured as needed.

That is, the difference between the acceleration GF1 in the front-rear (F, B) direction and the acceleration GW1 in the width (L, R) direction and the reference values GFi, GWi, which are measured as needed, is the horizontal component of the gravitational acceleration when the vehicle 130 is tilted. Therefore, the tilt angle of the vehicle 130 can be calculated based on the difference in acceleration.
Japanese Patent No. 3622723

  However, in the conventional inclination sensor 110, one detection element detects the front-rear (F, B) direction of the vehicle 130 and the other detection element individually detects the vehicle width (L, R) direction, and relatively the vehicle Inclination that is likely to occur in the vehicle 130, that is, when the vehicle 130 is accelerated or braked, or when the vehicle 130 is inclined in the front-rear (F, B) direction or due to theft using a tow truck or the like. The inclination in the width (L, R) direction of the vehicle is detected only by one detection element. Therefore, for example, when one of the detection elements deteriorates, only the inclination in the vehicle width (L, R) direction is detected by the other detection element, so that the detection accuracy may be significantly reduced. There was a problem.

  Therefore, an object of the present invention is to realize a vehicle-mounted tilt sensor and a vehicle tilt detection method that can improve the detection accuracy of the tilt angle.

  In order to achieve the above object, according to the present invention, the invention according to claim 1 includes two or more detection elements having specific detection directions, and detects the inclination of the vehicle based on detection signals output from these detection elements. In a possible vehicle-mounted tilt sensor, when the tilt sensor is mounted on the vehicle, a unique detection direction GR of one of the two or more detection elements is relative to the longitudinal direction of the vehicle. Thus, the unique detection direction GL of the other detection element that forms the first angle θR is a second angle θL that is set on the opposite side of the first angle θR with respect to the longitudinal direction of the vehicle. The technical means of making is used.

  According to a second aspect of the present invention, in the vehicle-mounted tilt sensor according to the first aspect, the specific detection direction GR and the specific detection direction GL are substantially parallel to a reference plane of a vehicle body of the vehicle. The technical means of being set is used.

  According to a third aspect of the present invention, in the vehicle-mounted tilt sensor according to the first or second aspect, the technical means that the first angle θR and the second angle θL are substantially equal is used. .

  According to a fourth aspect of the present invention, in the vehicle-mounted tilt sensor according to any one of the first to third aspects, the first angle θR and the second angle θL are approximately 45 °. Use the technical means of being.

  According to a fifth aspect of the present invention, in the vehicle-mounted tilt sensor according to any one of the first to third aspects, the specific detection direction GR is a right front wheel and a left rear side in a four-wheel vehicle. The unique detection direction GL corresponds to a direction of a second diagonal line connecting a left front wheel and a right rear wheel in the four-wheel vehicle. The technical means is used.

  According to a sixth aspect of the present invention, in the vehicle-mounted tilt sensor according to any one of the first to fifth aspects, the vehicle-mounted tilt sensor is a capacitive acceleration sensor. Use technical means.

  According to a seventh aspect of the present invention, in the vehicle-mounted tilt sensor according to any one of the first to sixth aspects, the one detection element and the other detection element are one semiconductor package. The technical means of being used in the interior is used.

  According to an eighth aspect of the present invention, the vehicle-mounted tilt sensor according to any one of the first to seventh aspects is mounted in the vicinity of an intersection of the first diagonal line and the second diagonal line, A vehicle tilt detection method for detecting a tilt angle of the vehicle using a tilt sensor, the acceleration occurring in the specific detection direction GR based on a first detection signal sent from the one detection element. And a second acceleration detecting step for detecting an acceleration generated in the inherent detection direction GL based on a second detection signal sent from the other one of the detection elements. And a tilt detection step of detecting a tilt angle of the vehicle based on each acceleration detected by the first acceleration detection step and the second acceleration detection step.

  According to a ninth aspect of the invention, in the vehicle inclination detection method according to the eighth aspect, a technical means is used in which the vehicle-mounted inclination sensor is mounted inside a center console.

  According to a tenth aspect of the present invention, in the vehicle tilt detection method according to the eighth or ninth aspect, the first acceleration detection step is first transmitted from the one detection element after the previous vehicle is parked. The detected signal is set as a first reference value, and the acceleration generated in the specific detection direction GR based on the first difference value that is the difference between the first detection signal and the first reference value. The second acceleration detecting step sets, as a second reference value, a detection signal first sent from the other detection element after the vehicle is parked in the previous period. A technical means is used to detect an acceleration generated in the inherent detection direction GR based on a second difference value that is a difference between the detection signal of the second reference value and the second reference value.

According to the first aspect of the present invention, in the vehicle-mounted inclination sensor that includes two or more detection elements having specific detection directions and can detect the inclination of the vehicle based on the detection signals output from the detection elements. When the tilt sensor is mounted on the vehicle, the unique detection direction GR of one of the two or more detection elements has a first angle θR with respect to the front-rear direction of the vehicle. The unique detection direction GL of one detection element forms a second angle θL that is set on the opposite side of the first angle θR with respect to the longitudinal direction of the vehicle.
Therefore, when the vehicle is inclined with respect to the front-rear direction and the vehicle is accelerated in the front-rear direction, when the acceleration is decomposed as a vector, an orthogonal projection component for the specific detection direction GR is obtained by one detection element. Can be detected. Further, the orthogonal projection component with respect to the specific detection direction GL can be detected by the other detection element. Similarly, even when the vehicle is tilted with respect to the width direction and acceleration in the width direction is generated in the vehicle, the orthogonal projection of the acceleration with respect to the specific detection direction is performed by one detection element and the other detection element. The component can be detected.
That is, two or more detection elements always detect the inclination of the vehicle in the front-rear direction or the inclination in the width direction of the vehicle caused by theft using the tow truck or the like when the vehicle is accelerated or braked. Can be detected.
Therefore, since the inclination in the direction that occurs frequently in the vehicle can always be detected by two or more detection elements, a detection element that can detect the inclination tilted in the front-rear direction and the width left-right direction of the vehicle is provided in each vehicle. Thus, it is possible to realize a vehicle-mounted tilt sensor and a vehicle tilt detection method that can improve the detection accuracy of the vehicle tilt angle as compared with a tilt sensor that detects the tilt of the vehicle.

  According to the second aspect of the present invention, the inherent detection direction GR and the inherent detection direction GL of the detection element are set substantially parallel to the reference plane of the vehicle body of the vehicle. The detection direction can be set in parallel to the plane where the change in acceleration or the like is greatest with the inclination of the vehicle. Therefore, since the amount of change that can be detected by the detection element increases, the detection accuracy of the vehicle inclination angle can be further improved.

  According to the invention described in claim 3, since the first angle θR and the second angle θL are substantially equal, the inclination in the front-rear direction of the vehicle and the inclination in the width direction of the vehicle are compared with one detection element and the other. It is possible to detect with substantially the same detection accuracy.

  In the invention according to claim 4, since the first angle θR and the second angle θL are approximately 45 °, the detection elements are detected in the vehicle front-rear direction and the vehicle width direction, which are frequently generated in the vehicle. That is, the detection direction is set at the same angle. For this reason, substantially the same detection accuracy can be obtained with respect to the inclination in the front-rear direction of the vehicle and the inclination in the width direction of the vehicle. In addition, since the angle formed with any detection element's inherent detection direction with respect to the inclination in any direction of the vehicle is 45 ° or less, the detection accuracy does not greatly change depending on the inclination direction of the vehicle. The detection accuracy of the tilt angle can be improved.

According to the invention described in claim 5, the inherent detection direction GR corresponds to the direction of the first diagonal line connecting the right front wheel and the left rear wheel in the four-wheel vehicle, and the inherent detection direction GL is Since this corresponds to the direction of the second diagonal line connecting the left front wheel and the right rear wheel in the four-wheel vehicle, it is possible to detect the inclination generated in the direction of the farthest wheel in the four-wheel vehicle.
Therefore, since the inclination can be detected in the direction in which the inclination of the vehicle changes the most by the steering of the wheel, the detection accuracy of the inclination angle of the vehicle can be improved.

  As in the sixth aspect of the present invention, a capacitance type acceleration sensor can be used as the vehicle-mounted tilt sensor.

  According to the invention described in claim 7, since the one detection element and the other detection element are housed in one semiconductor package, the vehicle-mounted tilt sensor can be miniaturized.

According to the invention described in claim 8, the vehicle-mounted tilt sensor is mounted in the vicinity of the intersection of the first diagonal line and the second diagonal line, for example, inside the center console as in the invention described in claim 9. Based on the first detection signal sent from one detection element in the first acceleration detection step, the acceleration generated in the specific detection direction GR is detected, and another detection element is detected in the second acceleration detection step. Acceleration detected in the specific detection direction GL is detected based on the second detection signal sent from the first detection signal, and based on the accelerations detected by the first acceleration detection step and the second acceleration detection step by the inclination detection step. To detect the inclination of the vehicle.
Since the vehicle-mounted tilt sensor is mounted in the vicinity of the intersection between the first diagonal line and the second diagonal line, the distance from each wheel to the vehicle-mounted tilt sensor becomes substantially equal. Since the inclination of the vehicle is caused by the posture of the vehicle body in the vicinity of the wheels, the inclination of the vehicle in the front-rear direction and the width direction can be detected in a balanced manner, and the detection accuracy does not change greatly depending on the inclination direction of the vehicle. Therefore, the detection accuracy of the tilt angle can be improved.

According to the tenth aspect of the present invention, in the first acceleration detection step, after the vehicle is parked, a detection signal first transmitted from one detection element is set as the first reference value, and the first detection is performed. Based on the first difference value, which is the difference between the signal and the first reference value, the acceleration generated in the specific detection direction GR is detected, and after the vehicle is parked by the second acceleration detection step, another one is detected. A detection signal first transmitted from the detection element is set as a second reference value, and the specific detection direction is determined based on a second difference value that is a difference between the second detection signal and the second reference value. The acceleration generated in the GL is detected.
Therefore, since the change in the current vehicle posture with respect to the posture when the vehicle is parked can be detected as a change in acceleration, the detection accuracy of the vehicle tilt angle can be improved.

  An embodiment of a vehicle-mounted tilt sensor and a vehicle tilt detection method according to the present invention will be described with reference to the drawings. The directions of arrows F, B, L, and R in FIGS. 1, 2, and 4 are respectively the front (F), rear (B), left (L), and right (R) directions of the vehicle 30. Equivalent to.

(Tilt sensor structure)
As shown in FIG. 1, the inclination sensor 10 includes a substrate 11 on which electronic components such as detection elements 12R and 12L and a microcomputer 13 (hereinafter referred to as “microcomputer”) are mounted, and a module case 14 that stores the substrate 11. Consists of FIG. 1 shows a shape in which the upper part of the box-shaped module case 14 is removed.

  The detection elements 12R and 12L are elements that can detect an inclination in a predetermined direction. For example, a beam structure (not shown) of opposed comb-shaped fixed electrodes and movable electrodes formed on a semiconductor substrate. A capacitance type detection unit. Thereby, when acceleration is applied in a predetermined direction, the movable electrode is displaced in the direction in which the acceleration is applied, and the interval between the fixed electrode and the movable electrode changes. For this reason, the magnitude of the applied acceleration can be detected as a change in capacitance between the two. This change in capacitance is output as a detection signal corresponding to the capacitance by a signal generation circuit and a demodulation circuit (not shown) controlled by the microcomputer 13.

  As described above, since the detection elements 12R and 12L can detect the acceleration applied around the predetermined direction, the detection element 12L is mounted on the substrate 11 so as to form an angle θL with respect to the central axis KK ′ of the vehicle 30 and detected. The element 12R is mounted on the substrate 11 so as to form an angle θR set on the opposite side of the angle θL with respect to the central axis KK ′. In the present embodiment, for example, both the angle θL and the angle θR are set to 45 °. As a result, as will be described later, when the vehicle starts and brakes, or when the vehicle 30 is tilted in the front-rear (F, B) direction caused by theft using a tow truck, or when the vehicle 30 turns, etc. The inclination in the width (L, R) direction of 30 can always be detected by the two detection elements 12L, 12R.

  Here, the calculation method of the inclination angle of the vehicle according to the embodiment of the present invention will be described with reference to FIG. In FIG. 2, a plane defined by the front-rear (F, B) direction of the vehicle 30 and the width (L, R) direction of the vehicle 30, the detection direction GR of the detection element 12R, and the detection direction GL of the detection element 12L, It is shown. The detection direction GR and the detection direction GL form an angle of 45 ° with respect to the front-rear (F, B) direction of the vehicle 30 and the width (L, R) direction of the vehicle 30, respectively.

  By the way, the acceleration generated in the vehicle 30 can be expressed as a vector on the plane described above. Here, in FIG. 2, after the vehicle 30 is parked (after the ignition switch is turned off), the vector α indicating the acceleration associated with the inclination of the vehicle 30 first detected by the detection elements 12R and 12L, the vehicle 30 is parked. , The vector β indicating the acceleration accompanying the inclination of the vehicle 30 detected by the detection elements 12R and 12L at predetermined time intervals, and the vector γ which is the acceleration change occurring in the vehicle 30 and the difference between the vector β and the vector α are represented. ing.

  The vector α is decomposed into an orthogonal projection component GRi with respect to the detection direction GR of the detection element 12R and an orthogonal projection component GLi with respect to the detection direction GL of the detection element 12L, and is represented as a position vector (GRi, GLi). The orthogonal projection component GRi is detected by the detection element 12R and sent to the microcomputer 13 described later as an acceleration signal GRi. Further, the orthogonal projection component GLi is detected by the detection element 12L and sent to the microcomputer 13 as an acceleration signal GLi.

  The vector β is decomposed into an orthogonal projection component GR1 with respect to the detection direction GR of the detection element 12R and an orthogonal projection component GL1 with respect to the detection direction GL of the detection element 12L, and is represented as a position vector (GR1, GL1). The orthogonal projection component GR1 is detected by the detection element 12R and sent to the microcomputer 13 as an acceleration signal GR1. Further, the orthogonal projection component GL1 is detected by the detection element 12L and is sent to the microcomputer 13 as an acceleration signal GL1.

  The vector γ is a difference between the vector β and the vector α, and is represented as a position vector (GR1-GRi, GL1-GLi) by the difference value of the orthogonal projection component. Since this vector γ is a horizontal component of the gravitational acceleration when the vehicle 30 is tilted with respect to the ground plane G (FIG. 3), the tilt angle of the vehicle is calculated based on the difference values GR1-GRi and GL1-GLi. be able to.

  As described above, since the vectors α and β indicating the acceleration accompanying the inclination of the vehicle 30 can always be detected by the two detection elements 12R and 12L, the detection accuracy of the inclination angle of the vehicle 30 can be improved.

  Further, the detection directions GR and GL of the detection elements 12R and 12L have the same angle (45) with respect to the front and rear (F and B) direction of the vehicle 30 and the width (L and R) direction of the vehicle 30 that are frequently generated in the vehicle 30. )), It is possible to obtain substantially the same detection accuracy with respect to the inclination of the vehicle 30 in the front-rear (F, B) direction and the inclination of the vehicle 30 in the width (L, R) direction. .

  Here, the angle between the vector α or the vector β and at least one of the detection direction GL of the detection element 12L and the detection direction GR of the detection element 12R is always 45 ° or less. For this reason, since the detectable range is 0 to 45 ° with respect to at least one of the detection elements, the detection accuracy does not change greatly depending on the inclination direction of the vehicle 30, and the detection accuracy of the inclination angle of the vehicle 30 can be improved. .

  Furthermore, the detection directions of the detection elements 12L and 12R are set substantially parallel to the reference plane of the vehicle body 31, that is, the ground plane G where the vehicle 30 is parked. As a result, the detection directions of the detection elements 12L and 12R can be set in parallel to the plane where the change in acceleration is greatest with the inclination of the vehicle 30, and the detection accuracy of the inclination angle of the vehicle 30 can be further improved.

  As shown in FIG. 1, the microcomputer 13 is a so-called one-chip microcomputer incorporating a memory device such as a ROM and a RAM, an interface device, etc., for example, and an inclination described later based on detection signals input from the detection elements 12L and 12R. A signal acquisition process is performed, and the tilt signal θ of the vehicle 30 is sent to the ECU 16.

  The module case 14 is a resin molded product formed in a rectangular box shape, and plate-shaped fixing portions 14b are formed on both sides in the longitudinal direction. The fixing portion 14b is for fixing the inclination sensor 10 inside a center console 36 provided in the vehicle 30, and mounting holes 14a and 14a are formed.

  On the other hand, a cylindrical connector 15 is formed on the short side surface of the module case 14, and a connector pin (not shown) is housed inside. Then, through this connector pin, the detection element 12 and the microcomputer 13 mounted on the substrate 11 can be electrically connected to the ECU 16 (FIG. 3) provided outside the module case 14. Yes. In the present embodiment, as shown in FIG. 3, the inclination sensor 10 and the ECU 16 are connected by a CAN (Control Area Network) 20.

(Tilt sensor placement)
As shown in FIG. 3, the tilt sensor 10 configured in this way is attached to the inside of the center console 36 of the vehicle 30 so as to be substantially parallel to the ground contact surface G of the vehicle body 31 of the vehicle 30. As shown in FIG. 4, the tilt sensor 10 is provided on the rear seat 35 side inside a center console 36 provided between the front right seat 33 and the front left seat 34.

  This position corresponds to the vicinity of the intersection X between the diagonal C1 connecting the left front wheel 32b and the right rear wheel 32c and the diagonal C2 connecting the right front wheel 32a and the left rear wheel 32d. The distances from the wheels 32a, 32b, 32c, 32d to the tilt sensor 10 are substantially equal. For this reason, the inclination sensor 10 can detect the inclination of the vehicle 30 in the front-rear (F, B) direction and the width (L, R) direction in a well-balanced manner, and the detection accuracy greatly varies depending on the inclination direction of the vehicle 30. Therefore, the detection accuracy of the tilt angle can be improved.

  The diagonal line C1 and the diagonal line C2 form an angle θc with the central axis K-K ′ in the front-rear (F, B) direction of the vehicle 30, respectively. For example, when the wheel base is 2600 mm and the tread is 1490 mm, the angle θc is about 30 °. Therefore, by setting the above-described angles θR and θL to around 30 °, the vehicle tilts most by steering the wheel. Since the inclination can be detected in the changing direction, the detection accuracy of the vehicle inclination angle can be improved.

(Vehicle theft determination processing by a vehicle theft prevention device using an inclination sensor)
Next, the example which applied the vehicle antitheft device to the inclination sensor 10 of this embodiment is demonstrated. The vehicle antitheft device detects, for example, an abnormal inclination of the parked vehicle 30 with the inclination sensor 10 when a third party lifts the front wheel when carrying out the vehicle 30 without permission using a tow truck or the like. When the vehicle 30 is stolen, it is determined that the vehicle 30 has been stolen and an alarm such as an alarm sound can be issued by a horn or the like. The apparatus includes the inclination sensor 10, the ECU 16, a horn (not shown), and the like.

  Here, the outline of the vehicle theft determination processing by the vehicle theft determination device will be described with reference to FIG. This vehicle theft determination process is executed by the ECU 16 shown in FIG. 3, and is performed, for example, at predetermined time intervals after the ignition switch of the vehicle 30 is turned off.

First, in step S1, the ECU 16 acquires the inclination angle of the vehicle 30 as the inclination signal θ from the inclination sensor 10 of the present embodiment.
Next, in step S3, it is determined whether or not the tilt signal θ acquired in step S1 exceeds the threshold value θs.

  When it is determined that the inclination signal θ exceeds the threshold value θs (S3: Yes), it is determined that the vehicle 30 has been stolen because the front or rear of the vehicle 30 is inclined at an unexpected angle. Then, an alarm is issued in the subsequent step S5.

  On the other hand, when it is determined that the inclination signal θ does not exceed the threshold value θs (S3: No), it is determined that the vehicle 30 has not been stolen. The determination process ends.

(Inclination signal acquisition processing)
The outline of the vehicle theft determination process performed by the vehicle theft determination apparatus is as described above. Here, the details of the inclination signal acquisition process in step S1 will be described in detail with reference to FIG. This inclination signal acquisition process is executed in the microcomputer 13 shown in FIG.

  First, in the inclination signal acquisition process, a process of determining whether or not a reference value has been set in step S101 is performed. Specifically, after the vehicle 30 is parked (after the ignition switch is turned off), the acceleration signal GRi (FIG. 2) first sent based on the acceleration generated in the GL direction from the detection element 12L and the detection element 12R first. It is determined whether the acceleration signal GRi (FIG. 2) sent based on the acceleration generated in the GR direction is set as a reference value (S101: Yes) or not (S101: No). Here, the reference value is cleared when a predetermined operation is performed, for example, when the ignition switch is turned off.

  If it is determined in step S101 that the acceleration signal GRi and the acceleration signal GRi are not set as reference values (S101: No), the process proceeds to step S103 to detect the acceleration signal GRi sent from the detection element 12R. In step S105, the acceleration signal GLi transmitted from the detection element 12L is detected.

  Subsequently, in step S107, the acceleration signal GRi and the acceleration signal GLi are set as the reference value GRi and the reference value GLi, respectively. When Steps S103, S105, and S107 are executed, the present inclination signal acquisition process ends at this time and waits for the next process.

  On the other hand, if it is determined in step S101 that the detection signal GRi and the detection signal GRi are set as reference values (S101: Yes), the process proceeds to the subsequent step S109. In step S109, acceleration detection processing by the detection element 12R is performed. In this acceleration detection process, the acceleration signal GR1 sent from the detection element 12R is detected. In the subsequent step S111, acceleration detection processing by the detection element 12L is performed. In this acceleration detection process, the acceleration signal GL1 sent from the detection element 12L is detected.

  In a succeeding step S113, a difference value calculation process is performed. In this difference value calculation process, difference values GR1-GRi and GL1-GLi between the acceleration signal GR1 detected in step S109 and the acceleration signal GL1 detected in step S111 and the reference values GRi and GLi are calculated.

  Subsequently, in step S115, the tilt signal θ is calculated by a known algorithm based on the difference values GR1-GRi, GL1-GLi, and the present tilt signal acquisition process is terminated.

  In this tilt signal acquisition process, either the reference value acquisition process by the detection element 12R in step S103 or the reference value acquisition process by the detection element 12L in step S105 may be executed first. Further, either the acceleration detection process by the detection element 12R in step S109 or the acceleration detection process by the detection element 12L in step S111 may be executed first.

[Effect of the embodiment]
(1) As described above, according to the invention of this embodiment, the detection elements 12L and 12R having unique detection directions are provided, and based on the detection signals (GLi, GL1, GRi, GR1) output from these elements. In the vehicle-mounted tilt sensor 10 that can detect the tilt of the vehicle 30, when the tilt sensor 10 is mounted on the vehicle 30, the detection direction GR of the detection element 12 </ b> R is relative to the central axis KK ′ of the vehicle 30. Are mounted on the substrate 11 so as to form an angle of 45 °. The detection direction GL of the detection element 12L is mounted on the substrate 11 so as to form an angle of 45 ° on the opposite side with respect to the central axis KK ′.

  Thereby, the width of the vehicle 30 that occurs when the vehicle 30 starts and brakes or when the vehicle 30 bends or tilts in the front-rear (F, B) direction caused by theft using a tow truck or the like ( Since the inclination in the (L, R) direction can always be detected by the two detection elements 12L, 12R, the vehicle is provided with a detection element that can detect the inclination inclined in the front-rear direction and the width left-right direction of the vehicle. Compared to a tilt sensor that detects the tilt of the vehicle 30, the accuracy of detecting the tilt angle of the vehicle 30 can be improved.

(2) The detection directions of the detection elements 12L and 12R are set at the same angle with respect to the front-rear (F, B) direction of the vehicle 30 and the width (L, R) direction of the vehicle 30, which are frequently generated in the vehicle 30. Therefore, substantially the same detection accuracy can be obtained with respect to the inclination of the vehicle 30 in the front-rear (F, B) direction and the inclination of the vehicle 30 in the width (L, R) direction.

  Further, since the angle formed with the detection direction of either of the detection elements 12L and 12R with respect to the inclination in any direction of the vehicle 30 is 45 ° or less, the detection accuracy does not greatly change depending on the inclination direction of the vehicle 30. In addition, the detection accuracy of the inclination angle of the vehicle 30 can be improved.

(3) The detection directions of the detection element 12L and the detection element 12R are set substantially parallel to the reference plane of the vehicle body 31, that is, the ground plane G where the vehicle 30 is parked. As a result, the first inherent detection direction and the second inherent detection direction of the tilt sensor are set substantially parallel to the reference plane of the vehicle body of the vehicle, so that the detection directions of the detection elements 12L and 12R are changed. In addition, it can be set parallel to the plane in which the acceleration changes most greatly with the inclination of the vehicle 30, and the detection accuracy of the inclination angle of the vehicle 30 can be further improved.

(4) The tilt sensor 10 is mounted in the vicinity of the intersection X between the diagonal C1 connecting the left front wheel 32 and the right rear wheel 32 and the diagonal C2 connecting the right front wheel 32 and the left rear wheel 32. Has been. Thereby, since the distance from each wheel 32 to the inclination sensor 10 becomes substantially equal, the inclination of the vehicle 30 in the front-rear (F, B) direction and the width (L, R) direction can be detected in a balanced manner. Since the detection accuracy does not change greatly depending on the tilt direction, the tilt angle detection accuracy can be improved.

(5) The difference values GR1-GRi and GL1-GLi between the acceleration signal GR1 and the acceleration signal GL1 and the reference values GRi and GLi are calculated, respectively, and the inclination signal θ is calculated based on the difference values GR1-GRi and GL1-GLi. Since the calculation can detect the change in the current posture of the vehicle 30 with respect to the posture when the vehicle 30 is parked as a change in acceleration, the accuracy of detecting the tilt angle of the vehicle 30 can be improved.

<Other embodiments>
(1) The inclination sensor 10 according to the present invention can be applied to a vehicle stability control system (VSC) by detecting the inclination of the traveling vehicle 30.

  In this case, the tilt sensor 10 is connected to the control ECU of the vehicle stability control system via the CAN 20 to send the tilt signal θ to the control ECU at predetermined time intervals. This makes it possible to provide the vehicle stability control system with tilt angle data as data necessary for attitude control of the vehicle 30. The reference value is cleared when, for example, the ignition switch is turned on.

(2) As the detection element 12, a detection element other than the capacitance type, for example, a piezoelectric type or a piezoresistive type detection element can be used. Further, the detection elements 12L and 12R may be housed in one semiconductor package. Thereby, a tilt sensor can be reduced in size.

It is explanatory drawing which shows the structure of the inclination sensor concerning embodiment of this invention. It is explanatory drawing which shows the calculation method of the inclination angle of the vehicle concerning embodiment of this invention. It is explanatory drawing which shows arrangement | positioning when it sees from the side surface of a vehicle of the inclination sensor concerning embodiment of this invention. It is explanatory drawing which shows arrangement | positioning when it sees from the upper direction of a vehicle of the inclination sensor concerning embodiment of this invention. It is a flowchart which shows the vehicle theft determination process by the vehicle antitheft device using the inclination sensor concerning embodiment of this invention. It is a flowchart which shows the inclination signal acquisition process by the inclination sensor concerning embodiment of this invention. It is explanatory drawing which shows the inclination detection method of the vehicle by the conventional vehicle-mounted inclination sensor.

Explanation of symbols

10 Tilt sensor (Vehicle mounted tilt sensor)
12R detection element (one detection element)
12L detection element (another detection element)
20 CAN
30 vehicles (four-wheel vehicles)
31 body 32a wheel (right front wheel)
32b Wheel (front left wheel)
32c wheel (right rear wheel)
32d wheel (left rear wheel)
C1 diagonal (second diagonal)
C2 diagonal (first diagonal)
GR detection direction (specific detection direction of one detection element)
GL detection direction (specific detection direction of another detection element)
θR Tilt signal (first angle)
θL Tilt signal (first angle)
X intersection

Claims (10)

In a vehicle-mounted tilt sensor that includes two or more detection elements having specific detection directions and can detect the tilt of the vehicle based on detection signals output from these detection elements.
When the tilt sensor is mounted on the vehicle, the unique detection direction GR of one of the two or more detection elements has a first angle θR with respect to the front-rear direction of the vehicle, A vehicle-mounted vehicle characterized in that a unique detection direction GL of another detection element forms a second angle θL set on the opposite side of the first angle θR with respect to the longitudinal direction of the vehicle. Type tilt sensor.   The vehicle-mounted tilt sensor according to claim 1, wherein the specific detection direction GR and the specific detection direction GL are set substantially parallel to a reference plane of a vehicle body of the vehicle.   3. The vehicle-mounted tilt sensor according to claim 1, wherein the first angle θR and the second angle θL are substantially equal.   The vehicle-mounted tilt sensor according to any one of claims 1 to 3, wherein the first angle θR and the second angle θL are approximately 45 °.   The unique detection direction GR corresponds to the direction of a first diagonal line connecting a right front wheel and a left rear wheel in a four-wheel vehicle, and the unique detection direction GL is a left front direction in the four-wheel vehicle. The vehicle-mounted tilt sensor according to any one of claims 1 to 3, which corresponds to a direction of a second diagonal line connecting the wheel and the right rear wheel.   The vehicle-mounted tilt sensor according to any one of claims 1 to 5, wherein the vehicle-mounted tilt sensor is a capacitance type acceleration sensor.   The vehicle-mounted tilt sensor according to any one of claims 1 to 6, wherein the one detection element and the other detection element are housed in one semiconductor package. A vehicle-mounted tilt sensor according to any one of claims 1 to 7 is mounted in the vicinity of an intersection between the first diagonal line and the second diagonal line, and the vehicle is tilted using the tilt sensor. A vehicle inclination detection method for detecting an inclination angle,
A first acceleration detecting step of detecting an acceleration generated in the inherent detection direction GR based on a first detection signal sent from the one detection element;
A second acceleration detecting step of detecting an acceleration generated in the inherent detection direction GL based on a second detection signal sent from the other one of the detection elements;
An inclination detection step of detecting an inclination angle of the vehicle based on each acceleration detected by the first acceleration detection step and the second acceleration detection step;
A vehicle tilt detection method comprising:   9. The vehicle tilt detection method according to claim 8, wherein the vehicle-mounted tilt sensor is mounted inside a center console. In the first acceleration detection step, after the vehicle is parked, a detection signal first transmitted from the one detection element is set as a first reference value, and the first detection signal and the first reference are set. A step of detecting an acceleration generated in the specific detection direction GR based on a first difference value that is a difference from the value;
In the second acceleration detection step, after the vehicle is parked, a detection signal first sent from the other detection element is set as a second reference value, and the second detection signal and the second detection signal are set. 10. The vehicle inclination according to claim 8, wherein an acceleration generated in the inherent detection direction GL is detected based on a second difference value that is a difference from a reference value of the vehicle. Detection method.

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