JP2012076633A - Headlight optical axis adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a headlight optical axis adjusting device advantageous to improvement of accuracy in the adjustment of an optical axis of a headlight.SOLUTION: The headlight optical axis adjusting device is taken into consideration that a load-displacement characteristic curve of a suspension device 20 includes first and second small change regions K1 and K2 having small changes in inclination and a large change region connecting the first and second small change regions K1 and K2 and having a larger change in inclination than the changes in inclination in the first and second small change regions K1 and K2. The range of a vehicle height is divided into a third vehicle height region a3 corresponding to the first small change region K1, a second vehicle height region a2 corresponding to the large change region K3, a first vehicle height region a1 corresponding to the second small change region K2 and a fourth vehicle height region a4. A characteristic curve for calculating control amount is fixed by four prediction expressions fixed corresponding to each of the first, second, third and fourth vehicle height regions a1, a2, a3 and a4. Each prediction expression is constituted of a function in which the control amount is shown by an N-order equation (N is a natural number of 2 or more) having the vehicle height as a variable.

Description

  The present invention relates to a headlamp optical axis adjusting device.

  In order to prevent the illumination light emitted from the headlight of the vehicle from being dazzling to the driver of the oncoming vehicle, the vehicle according to the pitch angle that is the inclination angle when the front and rear of the vehicle are tilted up and down There has been proposed a headlamp optical axis adjusting device for adjusting the direction of the optical axis of the headlamp. This type of headlamp optical axis adjustment device is configured to calculate a pitch angle based on a prediction formula from a vehicle height detected by a vehicle height sensor, and to adjust the direction of the optical axis according to the calculated inclination. ing. The inclination of the vehicle changes depending on conditions such as the number of passengers, the position of the seat on which the passenger sits, the presence or absence of luggage loaded on the trunk, and the weight of the luggage. Therefore, it is necessary to set the prediction formula so that the pitch angle can be calculated as accurately as possible in consideration of these conditions. Therefore, based on the output from the vehicle height sensor, the load condition of the vehicle is divided into three regions, a first region, a second region, and a third region, according to the magnitude, and the primary is different in inclination for each region. There has been proposed a headlamp optical axis adjustment device that uses a prediction formula in which the equations are connected (see Patent Document 1).

Japanese Patent No. 4424067

Since the change in the pitch angle according to the load condition of the vehicle is affected by the load-displacement characteristics of the suspension device provided in the vehicle, the prediction formula is based on the load-displacement characteristic curve of the suspension device. There is a need to.
In the above prior art, although a plurality of linear expressions are used as a prediction formula, a region where the change in inclination is large in the load-displacement characteristic curve of the suspension device is not particularly taken into consideration, and there is room for improvement in the prediction formula. There is.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a headlamp optical axis adjustment device that is advantageous in improving the accuracy of optical axis adjustment of a headlamp.

In order to achieve the above object, a headlight optical axis adjusting device according to the present invention includes vehicle height detection means for detecting a vehicle height at the front or rear of a vehicle, and a characteristic curve for calculating a pitch angle from the detected vehicle height. The pitch angle that is the inclination of the vehicle is calculated based on the angle, and the optical axis angle that is the angle that the optical axis of the vehicle headlamp makes with respect to the horizontal plane is within a predetermined allowable range based on the pitch angle. A control amount calculating means for determining the control amount of the optical axis angle and an optical axis adjusting means for adjusting the optical axis angle based on the determined control amount, and a suspension apparatus provided in the vehicle. The load-displacement characteristic curve connects the first and second small change regions having a small change in inclination with the first and second small change regions, and the inclinations of the first and second small change regions. A large change area where the change in inclination is larger than the change in The range includes a first vehicle height region corresponding to the first small change region, a second vehicle height region corresponding to the large change region, and a third vehicle corresponding to the second small change region. The pitch angle calculating characteristic curve is determined by three prediction formulas corresponding to the first, second, and third vehicle height regions, respectively, and each prediction formula is Is characterized in that the pitch angle is composed of a function represented by an Nth order expression (N is a natural number of 2 or more) with the vehicle height as a variable.
The headlamp optical axis adjusting device according to the present invention includes a vehicle height detection means for detecting a vehicle height at the front or rear of the vehicle, and a vehicle headlamp based on a characteristic curve for calculating a control amount from the detected vehicle height. A control amount calculating means for determining a control amount of the optical axis angle so that an optical axis angle which is an angle formed by an optical axis of the lamp with respect to a horizontal plane is within a predetermined allowable range; and the determined control amount And a load-displacement characteristic curve of a suspension device provided in the vehicle includes first and second small change regions having a small change in inclination, and an optical axis adjustment unit that adjusts an optical axis angle based on A large change area connecting between the first and second small change areas and having a change in inclination larger than the change in inclination of the first and second small change areas, and the range of the vehicle height is A first vehicle height region corresponding to the first small change region and a large change region; The control amount calculation characteristic curve is divided into a second vehicle height region and a third vehicle height region corresponding to the second small change region, and the first, second, and third vehicle heights Each prediction formula is defined by an Nth-order formula (N is a natural number of 2 or more) in which the control amount is a variable of the vehicle height. It consists of a function.

According to the present invention, by defining a prediction equation corresponding to a large change region where the change in inclination is large in the load-displacement characteristic curve of the suspension device, the characteristic of the suspension device that is not simple linear is more accurately predicted. Since it can be reflected, the pitch angle or the control amount can be calculated more accurately from the vehicle height.
Therefore, it is advantageous in ensuring the accuracy of adjusting the optical axis of the headlamp, compared to a case where a prediction formula is not defined for a large change region where the change in inclination is large in the load-displacement characteristic curve of the suspension device. Become.

It is explanatory drawing which shows the structure of the headlamp optical-axis adjustment apparatus of this Embodiment. 1 is a configuration diagram of a suspension device 20. FIG. 2 is a schematic diagram of a suspension device 20. FIG. 3 is a diagram showing a load-displacement characteristic curve of the suspension device 20. FIG. It is a block diagram which shows the structure of a headlamp optical axis adjustment apparatus. It is explanatory drawing of the characteristic curve for control amount calculation. It is a figure explaining the correspondence of the 1st thru / or the 4th vehicle height field and the 1st thru / or the 4th prediction formula. It is a diagram which shows the relationship between the rear vehicle height hr calculated | required about one vehicle, and pitch angle (theta) p. A characteristic curve for calculating the pitch angle defined by the prediction formula of the second order or higher and a characteristic curve for calculating the pitch angle defined by the prediction formula of only the primary expression when four types of suspension devices having different characteristics are used for one vehicle. It is explanatory drawing which compares. 4 is a flowchart showing an example of the operation of the headlamp optical axis adjustment device 10. 6 is a flowchart showing another example of the operation of the headlamp optical axis adjustment device 10.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the headlamp optical axis adjusting device 10 according to the present embodiment is mounted on a vehicle 2, and the vehicle 2 includes a suspension device 20. First, the suspension device 20 will be described. In the present embodiment, as shown in FIG. 2, the suspension device 20 includes a shock absorber 22, a coil spring 24, and a bump stopper 26. As shown in FIG. 3, the suspension device 20 is configured by arranging a shock absorber 22, a coil spring 24, and a bump stopper 26 in parallel. 2 and 3, the shock absorber 22 is arranged with the piston rod 22A facing upward, the upper part of the piston rod 22A is connected to the vehicle body 2A side, and the lower part of the cylinder 22B is connected to the wheel 4 side. Yes. More specifically, a piston (not shown) at the base end of the piston rod 22A is accommodated in the cylinder 22B. When the piston moves in the cylinder 22B, the oil passes through the orifice of the piston and the kinetic energy is attenuated. The coil spring 24 is interposed between an upper spring seat 25A connected to the vehicle body 2A around the shock absorber 22 and a lower spring seat 25B connected to the cylinder 22B, and separates the spring seats 25A and 26B. Energized in the direction.

  The bump stopper 26 is fitted into the piston rod 22A portion protruding from the cylinder 22B. The upper end of the bump stopper 26 is in contact with the upper spring seat 25A. The lower end of the bump stopper 26 is provided so as to be in contact with the upper end of the cylinder 22B. More specifically, when the shock absorber 22 is not operating, a predetermined gap, that is, a buffer clearance Δc is formed between the lower end of the bump stopper 26 and the upper end of the cylinder 22B. When the piston rod 22A is immersed in the cylinder 22B, the lower end of the bump stopper 26 comes into contact with the upper end of the cylinder 22B. When a load is input to the bump stopper 26, the load is absorbed by the deformation of the bump stopper 26 between the upper spring seat 25A and the upper end of the cylinder 22B. As a material for forming the bump stopper 26, various conventionally known elastic materials such as rubber and urethane foam can be used.

  Accordingly, the coil spring 24 constitutes a buffering means that softens the shock by displacing the impact applied to the vehicle when an impact is applied to the vehicle. The shock absorber 22 constitutes vibration damping means for damping the vibration of the coil spring 24. The bump stopper 26 operates when the coil spring 24 is displaced excessively, and suppresses excessive displacement of the coil spring 24. In the present embodiment, the case where the coil spring 24 is used as the buffer means has been described. However, a conventionally known buffer member such as a plate spring or an air spring can be used as the buffer means. In the present embodiment, the case where the shock absorber 22 is used as the vibration damping means has been described. However, the presence / absence of the vibration damping means and the configuration of the vibration damping means are arbitrary.

  FIG. 4 is a diagram showing a load-displacement characteristic curve of the suspension device 20. That is, in FIG. 4, the horizontal axis represents the displacement of the suspension device 20, and the vertical axis represents the load input to the suspension device 20. The load-displacement characteristic curve connects the first and second small change regions K1 and K2 having a small change in inclination and the first and second small change regions K1 and K2 to connect the first and second small change regions K1 and K2. And a large change area K3 in which the change in inclination is larger than the change in inclination in the small change areas K1 and K2. The first small change region K1, the large change region K3, and the second small change region K2 have a large displacement amount in this order. When the load input to the suspension device 20 increases, only the coil spring 24 is deformed at first, and the coil spring 24 is linearly deformed according to Hook's law, and the change in the slope of the load-displacement characteristic curve is small. Yes. This state corresponds to the first small change region K1. When the load further increases, the upper end of the cylinder 22B and the lower end of the bump stopper 26 come into contact with each other. That is, the load is input only to the coil spring 24 before the upper end of the cylinder 22B comes into contact with the lower end of the bump stopper 26. After the upper end of the cylinder 22B comes into contact with the lower end of the bump stopper 26, a load is input to both the coil spring 24 and the bump stopper 26. For this reason, the slope of the load-displacement characteristic curve changes greatly. This state corresponds to the large change region K3. That is, the large change region K3 is a region including the boundary between the region where only the coil spring 24 is operating and the region where both the coil spring 24 and the bump stopper 26 are operating in the load-displacement characteristic curve. . When the load further increases, both the coil spring 24 and the bump stopper 26 are deformed, so that the change in the slope of the load-displacement characteristic curve is small. This state corresponds to the second small change region K2.

  Next, the headlamp optical axis adjusting device 10 will be described. As shown in FIG. 1, the headlamp optical axis adjusting device 10 includes a headlamp 12, an actuator 14, a vehicle height sensor 16, and an optical axis adjusting ECU 18. The headlamp 12 is provided at intervals in the left-right width direction of the front portion of the vehicle 2, and irradiates illumination light in front of the vehicle 2. The headlamp 12 includes a lamp 12A that generates illumination light, a reflector 12B that holds the lamp 12A and reflects the illumination light forward, and a case (not shown) that houses the lamp 12A and the reflector 12B. ing. The rear upper portion of the reflector 12B is supported so as to be swingable about an axis extending in the vehicle width direction with respect to the case. Therefore, the optical axis of the headlamp 12 changes up and down by swinging the reflector 12B. The actuator 14 swings the reflector 12B by moving the lower back portion of the reflector 12B back and forth based on a control signal supplied from the optical axis adjustment ECU 18.

  The vehicle height sensor 16 is provided between the suspension device 20 at the rear of the vehicle 2 and the rear portion of the vehicle 2 in the vicinity of the suspension device 20, and the relative displacement Δh between the suspension device 20 and the rear of the vehicle 2. Is detected and supplied to the optical axis adjustment ECU 18. The vehicle height sensor 16 is provided between the suspension device 20 at the front portion of the vehicle 2 and the location of the front portion of the vehicle 2 in the vicinity of the suspension device 20, and between the suspension device 20 and the front portion of the vehicle 2. The relative displacement amount may be detected and supplied to the optical axis adjustment ECU 18.

  The optical axis adjustment ECU 18 includes a CPU, a ROM that stores and stores a control program, a RAM as an operation area of the control program, an interface unit that interfaces with peripheral circuits and the like. As shown in FIG. 5, the optical axis adjustment ECU 18 implements a vehicle height detection means 30, a control amount calculation means 32, and an optical axis adjustment means 34 by executing the control program.

  The vehicle height detection means 30 calculates the vehicle height at the rear portion of the vehicle 2 (hereinafter referred to as the rear vehicle height hr) based on the relative displacement Δh between the suspension device 20 and the rear portion of the vehicle 2 supplied from the vehicle height sensor 16. By doing so, the rear vehicle height hr is detected.

  The control amount calculation means 32 calculates the pitch angle θp, which is the inclination of the vehicle, from the detected rear vehicle height hr based on the characteristic curve for pitch angle calculation, and the optical axis L of the headlamp 12 based on the pitch angle θp. The control amount of the optical axis angle is determined so that the optical axis angle, which is an angle formed with respect to the horizontal plane, falls within a predetermined allowable range. Alternatively, the control amount calculation means 32 is an angle formed by the optical axis L of the headlamp 12 of the vehicle 2 with respect to the horizontal plane based on the control amount calculation characteristic curve from the rear vehicle height hr detected by the vehicle height detection means 30. The control amount CA of the optical axis angle is determined so that the optical axis angle is within a predetermined allowable range. The allowable range of the optical axis angle, the characteristic curve for calculating the pitch angle, and the characteristic curve for calculating the control amount will be described later. The calculation of the pitch angle θp based on the characteristic curve for pitch angle calculation or the calculation of the control amount CA based on the characteristic curve for control amount calculation may be performed by the control amount calculation means 32 calculating a prediction formula described later. . Alternatively, a map representing these characteristic curves may be stored in advance in the optical axis adjustment ECU 18 and the control amount calculation means 32 may refer to the map.

  The optical axis adjustment unit 34 controls the actuator 14 by supplying a control signal to the actuator 14 based on the control amount determined by the control amount calculation unit 32, thereby adjusting the optical axis angle of the headlamp 12. Is. Therefore, the swing angle of the reflector 12B, in other words, the swing angle of the optical axis L of the headlamp 12 is determined by the control amount supplied from the control amount calculating means 32 to the optical axis adjusting means 34.

  Next, the allowable range of the optical axis angle will be described. The optical axis angle of the headlamp 12 needs to be determined so that the illumination light emitted from the headlamp 12 is prevented from being dazzled by the driver of the oncoming vehicle. According to the regulations, the optical axis angle of the headlamp 12 is determined using a numerical value B defined as follows. That is, as shown in FIG. 1, a wall surface W orthogonal to the horizontal plane is provided at a position 10 m ahead of the vehicle. The illumination light of the headlamp 12 is irradiated from the direction orthogonal to the wall surface W, the upper limit position of the irradiation range centered on the optical axis L of the headlamp 12 projected on the wall surface W is A1, and the lower limit position is A2. To do. At this time, the distance between the position C of the headlamp 12 projected on the wall surface W and the upper limit position A1 is d1, and the distance between the center position C and the lower limit position A2 is d2. A value obtained by dividing the distance d1 or the distance d2 by 10 m is B. In the present specification, the numerical value B is referred to as a beam tilt rate. The regulations require that the beam tilt rate B is −2.5% ≦ B ≦ −0.5%. In addition, it is preferable that the optical axis angle of the headlamp 12 irradiates as far as possible while suppressing the illumination light from being dazzled by the driver of the oncoming vehicle. From this point of view, a description will be given of the case where the distance d1 between the center position C of the headlamp 12 projected on the wall surface W and the upper limit position A1 is used in calculating the beam inclination rate B. That is, it is necessary to adjust the optical axis angle of the headlamp 12 within an allowable angle in which the beam inclination rate B is −2.5% ≦ B ≦ −0.5%.

Next, the pitch angle calculation characteristic curve and the control amount calculation characteristic curve will be described. When a person rides on the vehicle 2 or loads are loaded, the rear vehicle height hr changes. For example, when the person gets on the driver's seat, the person gets on the driver's seat and the passenger's seat, or the person gets on the driver's seat and the rear seat, the rear vehicle height hr changes. Alternatively, when the load is loaded on the passenger seat, loaded on the rear seat, or loaded on the trunk, the rear vehicle height hr changes. Due to such a difference in load conditions, the rear vehicle height hr changes, and the pitch angle θp of the vehicle 2 changes according to the rear vehicle height hr. Then, the optical axis angle of the headlamp 12 changes by the change in the pitch angle θp of the vehicle 2. Therefore, if the optical axis angle of the headlamp 12 is adjusted by controlling the actuator 14 so as to cancel the pitch angle θp, the optical axis angle of the headlamp 12 can be adjusted within an allowable range. Therefore, the pitch angle θp of the vehicle 2 corresponding to the rear vehicle height hr is predicted, and the adjustment amount of the optical axis angle of the headlamp 12 sufficient to cancel the predicted pitch angle θp, in other words, the control amount CA of the actuator 14 May be calculated. Therefore, a pitch angle calculation characteristic curve indicating the relationship between the rear vehicle height hr and the pitch angle θp of the vehicle 2 is created, and the pitch angle of the vehicle 2 is determined from the rear vehicle height hr using the pitch angle calculation characteristic curve. It is only necessary to obtain θp and calculate the control amount CA of the actuator 14 that is sufficient to cancel the pitch angle θp. In the above procedure, (1) calculation of the pitch angle θp using the characteristic curve for pitch angle calculation and (2) calculation of the control amount CA of the actuator 14 from the pitch angle θp are performed separately. However, since the pitch angle θp and the control amount CA have a one-to-one correspondence in the first place, if a characteristic curve that associates the rear vehicle height hr with the control amount CA is prepared from the beginning, the rear vehicle height hr is prepared. This is advantageous in increasing the efficiency of processing required to calculate the control amount CA from the control amount CA. That is, as such a characteristic curve, a control amount calculation characteristic curve indicating the relationship between the rear vehicle height hr and the control amount CA of the actuator 14 is created, and the rear vehicle height is calculated using the control amount calculation characteristic curve. The control amount CA of the actuator 14 may be calculated from hr. As shown in FIG. 6, the control amount calculation characteristic curve indicates the relationship between the rear vehicle height hr and the control amount CA, in other words, the relationship between the rear vehicle height hr and the magnitude of the control signal supplied to the actuator 14. It is a curve. The control amount CA is an arbitrary unit. For example, when the control signal is a voltage signal, the magnitude of the control signal can be represented by a voltage ratio (%) that is a ratio to a predetermined reference voltage. In FIG. 6, the rear vehicle height hr indicated on the horizontal axis is lower as it goes to the left and higher as it goes to the right. The magnitude of the control signal shown on the vertical axis is larger as it goes upward and smaller as it goes downward. When the rear vehicle height hr is specified in the control amount calculation characteristic curve, the magnitude of the control signal supplied to the actuator 14 is determined.
That is, in FIG. 6, as the rear vehicle height hr decreases (as the vehicle body posture leans backward), the optical axis of the headlamp 12 tends to be upward, so that the actuator 14 sets the optical axis of the headlamp 12 downward. Thus, the control amount CA is set. Further, the higher the rear vehicle height hr (the more the vehicle body posture leans forward), the more the optical axis of the headlamp 12 tends to be downward. CA is set. In other words, in FIG. 6, the control amount CA is controlled so that the optical axis of the headlamp 12 faces upward as the control amount CA becomes larger (upward) than the reference value. It is determined that the actuator 14 controls the optical axis of the headlamp 12 downward so that the optical axis of the headlamp 12 is reduced as it becomes smaller (downward). In addition, the vehicle height region a4 is on the extension line of the vehicle height region a3, and the control amount CA is set so that the optical axis of the headlamp 12 does not turn upward.

  In the present embodiment, as shown in FIG. 6, the range of the rear vehicle height hr is divided into first to fourth vehicle height ranges a1 to a4 in order from the lower rear vehicle height hr toward the higher one. Has been. The first vehicle height region a1 is determined corresponding to the second small change region K2. The second vehicle height region a2 is determined corresponding to the large change region K3. The third vehicle height region a3 is determined corresponding to the first small change region K1. The fourth vehicle height region a4 is a region in which the rear vehicle height is higher (the front vehicle height is lower) than the third vehicle height region a3, in other words, the vehicle body posture is bent forward. The fourth vehicle height region a4 corresponds to a region indicated by a broken line in FIG. 4, and this region has characteristics similar to those of the first small change region K1. The characteristic curve for calculating the control amount is determined by first to fourth prediction formulas corresponding to the first to fourth vehicle height regions a1 to a4, respectively. CA is composed of a function represented by an Nth order expression (N is a natural number of 2 or more) with the rear vehicle height hr as a variable.

  More specifically, reference characters BV1, BV2, and BV3 in the figure indicate boundary values that divide the first to fourth vehicle height regions a1 to a4, and the first to fourth vehicle height regions a1 to a4. Is defined as shown in FIG. As shown in FIG. 7, first to fourth prediction formulas are respectively defined corresponding to the first to fourth vehicle height regions a1 to a4. In each prediction formula, A3, B1, B2, B3, B4, C1, C2, C3, C4, D1, D2, D3, and D4 are constants. The first to fourth prediction formulas are configured by quadratic formulas or cubic formulas, and specifically, the first, second, and fourth prediction formulas are configured by quadratic formulas, The prediction formula is a cubic formula. Thus, by defining the control amount calculation characteristic curve using a second-order or higher-order prediction formula, the accuracy when controlling the optical axis angle is improved as compared with the case where the first-order prediction formula is used. It will be advantageous. In other words, it is advantageous to make the beam inclination rate B fall within an allowable angle satisfying −2.5% ≦ B ≦ −0.5%. In addition, when using the above-mentioned characteristic curve for calculating the pitch angle instead of the characteristic curve for calculating the control amount, the same prediction formula as in the above case may be used, and specifically, the following may be performed. . That is, each prediction formula that defines the characteristic curve for calculating the pitch angle is composed of a function represented by an Nth order formula (N is a natural number of 2 or more) in which the pitch angle is a vehicle height. In addition, the characteristic curve for calculating the pitch angle is determined using a second-order or higher-order prediction formula, which is advantageous in improving the accuracy in controlling the optical axis angle compared to the case of using the first-order prediction formula. Become. The reason why it is advantageous to use the second-order or higher-order prediction formula to improve the accuracy in controlling the optical axis angle will be described later.

  Next, the operation of the headlamp optical axis adjusting device 10 will be described. First, the case where the control amount calculation characteristic curve is used will be described with reference to the flowchart of FIG. When receiving the relative displacement amount Δh detected by the vehicle height sensor 16 (step S10), the optical axis adjustment ECU 18 calculates the vehicle height hr from the relative displacement amount Δh (step S12: vehicle height detection means 30). Next, the optical axis adjustment ECU 18 calculates the control amount CA based on the control amount calculation characteristic curve FN from the calculated vehicle height hr (step S14: control amount calculation means). Next, the optical axis adjustment ECU 18 supplies the actuator 14 with a control signal according to the calculated control amount CA and drives it (step S16: optical axis adjustment means 34) to adjust the optical axis angle of the headlamp 12 ( Step S18: Optical axis adjusting means 34). Thereby, the optical axis angle of the headlamp 12 is adjusted so that the beam inclination rate B is within the allowable range.

  Next, the case where the pitch angle calculation characteristic curve is used will be described with reference to the flowchart of FIG. Steps S20 and S22 are the same as steps S10 and S12 in FIG. The optical axis adjustment ECU 18 calculates the pitch angle θp from the calculated vehicle height hr based on the pitch angle calculation characteristic curve FN (step S24: control amount calculation means 32). Next, the optical axis adjustment ECU 18 calculates a control amount CA from the calculated pitch angle θp (step S26: control amount calculation means). Next, the optical axis adjustment ECU 18 supplies the actuator 14 with a control signal according to the calculated control amount CA and drives it (step S28: optical axis adjustment means 34) to adjust the optical axis angle of the headlamp 12 ( Step S30: Optical axis adjusting means 34). Thereby, the optical axis angle of the headlamp 12 is adjusted so that the beam inclination rate B is within the allowable range.

  Next, the effect of the headlamp optical axis adjusting device 10 in the present embodiment will be described. The relationship between the vehicle height hr and the pitch angle θp is affected by the load-displacement characteristic curve of the suspension device 20. As shown in FIG. 4, since the load-displacement characteristic curve of the suspension device 20 is not a simple linear shape, it is difficult to accurately represent the relationship between the vehicle height hr and the pitch angle θp with a simple linear shape. Therefore, even if the relationship between the vehicle height hr and the pitch angle θp is determined by a combination of three primary equations as in the prior art, there is a limit in accurately calculating the pitch angle θp from the vehicle height hr. Therefore, even if the optical axis adjustment of the headlamp 12 is performed based on the obtained pitch angle θp, there is a limit in ensuring the accuracy of the optical axis adjustment.

  In contrast, according to the present invention, the load-displacement characteristic curve of the suspension device 20 includes the first and second small change regions K1 and K2 in which the change in inclination is small, and the first and second small change regions K1. , K2 and a large change region K3 in which the change in inclination is larger than the change in inclination in the first and second small change regions K1 and K2. That is, the vehicle height ranges are the third vehicle height region a3 corresponding to the first small change region K1, the second vehicle height region a2 corresponding to the large change region K3, and the second small change region K2. Are divided into a first vehicle height region a1 and a fourth vehicle height region a4, and the control amount calculation characteristic curves are divided into first, second, third and fourth vehicle height regions a1, a2. , A3, and a4 are determined by four prediction formulas corresponding to each, and each prediction formula is expressed by an Nth order formula (N is a natural number of 2 or more) in which the control amount is a variable. Consists of functions. Alternatively, the pitch angle calculation characteristic curve is determined by four prediction formulas corresponding to the first, second, third, and fourth vehicle height regions a1, a2, a3, and a4, respectively. The pitch angle is composed of a function expressed by an Nth order expression (N is a natural number of 2 or more) with the vehicle height as a variable. In this way, by defining a prediction formula corresponding to a large change region where the change in inclination is large in the load-displacement characteristic curve of the suspension device 20, the characteristics of the suspension device 20 that is not simple linear are more accurately predicted. Since it can be reflected, the control amount CA or the pitch angle θp can be accurately calculated from the vehicle height hr. Therefore, in ensuring the accuracy of the optical axis adjustment of the headlamp 12 as compared with the case where the prediction formula is not defined for the large change region where the change in inclination is large in the load-displacement characteristic curve of the suspension device 20. It will be advantageous.

In the present embodiment, the case where the vehicle height range is divided into four vehicle height regions a1 to a4 has been described. However, the first and second small change regions K1 and K2 and the large change region of the suspension device 20 are described. Corresponding to each of K3, the vehicle height range may be divided into at least three vehicle height regions. However, if the vehicle is divided into more vehicle height regions as in the present embodiment, the pitch angle θp or the control amount CA with respect to the vehicle height hr can be calculated more finely according to the load condition. This is even more advantageous in ensuring the accuracy of adjustment.
Moreover, although the case where the rear vehicle height hr is used as the vehicle height has been described in the present embodiment, it is needless to say that the front vehicle height may be used.

  Next, it is more advantageous to use a control amount calculation characteristic curve defined by a quadratic or higher-order prediction formula than to use a control amount calculation characteristic curve defined by a first-order formula. The point that using the characteristic curve for calculating the pitch angle defined by the equation is more advantageous than using the characteristic curve for calculating the pitch angle defined by the linear equation. In the following description, for the sake of convenience, the pitch angle calculation characteristic curve indicating the relationship between the rear vehicle height hr and the pitch angle θp will be described by comparing the case where the characteristic curve is determined by the Nth order equation and the case where the characteristic curve is determined by the primary expression. FIG. 8 is a diagram showing the relationship between the rear vehicle height hr and the pitch angle θp obtained for one vehicle. The rear vehicle height hr shown on the horizontal axis is higher as it goes to the left and lower as it goes to the right. The magnitude of the pitch angle θp shown on the vertical axis is larger as it goes upward (the front part of the vehicle 2 tends to be upward), and smaller as it goes downward (the front part of the vehicle 2 tends to be downward). In the figure, symbol FN indicates a characteristic curve for calculating a pitch angle determined by first to fourth prediction equations of second order or higher, and symbol F1 indicates a characteristic curve for calculating a pitch angle determined by four primary prediction equations. Show. Further, the curves other than the pitch angle calculation characteristic curves FN and F1 are predicted values indicating the rear vehicle height hr and the pitch angle θp calculated in consideration of variations in the characteristics of the suspension device 20, and these predicted values are: This is calculated by varying the load conditions such as the number of passengers (weight) with respect to the vehicle 2, seat position, presence / absence of luggage, and weight of luggage. Here, the characteristic of the suspension device 20 is the degree of change in the stroke amount with respect to the load (load-displacement characteristic curve). Then, with respect to the predicted value calculated as described above, the beam inclination rate B when the optical axis angle of the headlamp 12 is adjusted based on the pitch angle calculation characteristic curves FN and F1 is within an allowable range (−2 .5% ≦ B ≦ −0.5%) was examined. As a result, in the pitch angle calculation characteristic curve FN, the beam inclination rate B is within the allowable range, whereas in the pitch angle calculation characteristic curve F1, the beam inclination rate B is -2.5% to- It was found that the variation was 0.38%, exceeding the upper limit of the legally acceptable range. Therefore, the pitch angle calculation characteristic curve FN defined by the first to fourth prediction formulas of the second or higher order is used compared to the case where the pitch angle calculation characteristic curve F1 defined by the primary prediction formula is used. Thus, even if there is some variation in the characteristics of the suspension device 20, the beam inclination rate B can be reliably kept within the allowable range, in other words, to ensure the adjustment accuracy of the optical axis angle of the headlamp 12. Is advantageous.

  FIG. 9 shows a pitch angle calculation characteristic curve defined by a second-order or higher-order prediction formula and a pitch angle calculation determined by a first-order prediction formula when four types of suspension devices 20 having different characteristics are used for one vehicle. It is explanatory drawing which compares a characteristic curve. That is, a case will be described in which different suspension devices 20 are used depending on the specification (grade) even in the same vehicle type. In this example, when the characteristic curve for calculating the pitch angle defined by the prediction equation of the second order or higher is used, any one of the four types of suspension devices 20 is used by using the single characteristic curve for calculating the pitch angle FN. Even so, the beam inclination rate B can be kept within the allowable range. On the other hand, when the characteristic curve for calculating the pitch angle determined by the primary prediction formula is used, the beam inclination rate B is kept within the allowable range by using the two characteristic curves for calculating the pitch angle F1a and F1b. I was able to. In other words, when four types of suspension devices 20 are used, it is necessary to prepare at least two characteristic curves for pitch angle calculation F1a and F1b. Therefore, when the pitch angle calculation characteristic curve FN determined by the second-order or higher-order prediction formula is used, the suspension device 20 of the suspension apparatus 20 is compared with the case where the pitch angle calculation characteristic curve F1 determined by the first-order prediction formula is used. Even if there is a difference in characteristics, the beam inclination rate B can be reliably kept within the allowable range, in other words, the increase in the number of types of the optical axis adjustment ECU 18 can be suppressed, and thus the manufacturing cost can be reduced. Is advantageous. This is because the optical axis adjustment ECU 18 needs to store a program for calculating the pitch angle calculation characteristic curve or map data indicating the pitch angle calculation characteristic curve. This is because it is necessary to prepare as many types of characteristic curves as possible.

  2 ... Vehicle, 10 ... Headlight optical axis adjustment device, 12 ... Headlight, 14 ... Actuator, 20 ... Suspension device, 22 ... Vehicle height detection means, 24 ... Control amount calculation means, 26 …… Optical axis adjustment means, hr …… Rear vehicle height, θp …… Pitch angle, L …… Optical axis, FN …… Pitch angle calculation characteristic curve, K1 …… First small change region, K2 …… First 2 small change areas, K3 ... large change areas, a1 to a3 ... first to third vehicle height areas.

Claims (4)

Vehicle height detection means for detecting the vehicle height at the front or rear of the vehicle;
A pitch angle, which is the inclination of the vehicle, is calculated from the detected vehicle height based on the characteristic curve for calculating the pitch angle, and the angle formed by the optical axis of the vehicle headlamp with respect to the horizontal plane based on the pitch angle. Control amount calculation means for determining the control amount of the optical axis angle so that the optical axis angle is within a predetermined allowable range;
An optical axis adjusting means for adjusting an optical axis angle based on the determined control amount;
The load-displacement characteristic curve of the suspension device provided in the vehicle connects the first and second small change regions where the change in inclination is small and the first and second small change regions to each other. , A large change area having a larger change in inclination than the change in inclination of the second small change area,
The range of the vehicle height corresponds to a first vehicle height region corresponding to the first small change region, a second vehicle height region corresponding to the large change region, and the second small change region. It is divided into the third vehicle height area,
The pitch angle calculation characteristic curve is determined by three prediction formulas corresponding to the first, second, and third vehicle height regions,
Each of the prediction formulas is composed of a function represented by an Nth order formula (N is a natural number of 2 or more) in which the pitch angle is a variable of the vehicle height.
A headlamp optical axis adjusting device characterized by that. Vehicle height detection means for detecting the vehicle height at the front or rear of the vehicle;
Based on the detected vehicle height based on the control amount calculation characteristic curve, the light is adjusted so that an optical axis angle, which is an angle formed by an optical axis of a vehicle headlamp with respect to a horizontal plane, is within a predetermined allowable range. A control amount calculating means for determining a control amount of the shaft angle;
An optical axis adjusting means for adjusting an optical axis angle based on the determined control amount;
The load-displacement characteristic curve of the suspension device provided in the vehicle connects the first and second small change regions where the change in inclination is small and the first and second small change regions to each other. , A large change area having a larger change in inclination than the change in inclination of the second small change area,
The range of the vehicle height corresponds to a first vehicle height region corresponding to the first small change region, a second vehicle height region corresponding to the large change region, and the second small change region. It is divided into the third vehicle height area,
The control amount calculation characteristic curve is determined by three prediction formulas corresponding to the first, second, and third vehicle height regions,
Each of the prediction formulas includes a function in which the control amount is represented by an Nth order formula (N is a natural number of 2 or more) with the vehicle height as a variable.
A headlamp optical axis adjusting device characterized by that. The suspension device includes a buffer unit that softens by displacing an impact applied to a vehicle, and a bump stopper unit that operates when the buffer unit is excessively displaced and suppresses the excessive displacement of the buffer unit.
The large change region is a region including a boundary between a region where only the buffering unit is operating and a region where both the buffering unit and the bump stopper unit are operating in the load-displacement characteristic curve. ,
The headlamp optical axis adjusting device according to claim 1 or 2, characterized in that An actuator for changing the optical axis angle of the headlamp is provided;
The adjustment of the optical axis angle by the optical axis adjustment means is performed by controlling the actuator based on the control amount.
The headlamp optical axis adjusting device according to any one of claims 1 to 3, wherein

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