Step-by-step height adjusting method based on two-axle automobile air suspension

Abstract

The invention relates to a step-by-step height adjusting method based on a two-axle automobile air suspension, which comprises the following specific steps of: firstly, recording that the height difference between a front axle and a rear axle is not greater than a threshold T span in an adjusting process, and in order to meet a height adjusting principle, generally, firstly lifting the rear axle and then lifting the front axle during lifting, and firstly descending the front axle and then descending the rear axle during descending; if some special initial height states may not meet the common front and rear axle adjusting sequence, values of height sensors of the four suspensions are read in real time, and the heights of a front axle and a rear axle are calculated through the following formulas: H front axle = (h left front + h right front) / 2 and H rear axle = (h left rear + h right rear) / 2 respectively, and the method has the advantages of being good in universality, suitable for different vehicle model items and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of two-axle vehicle air suspensions, and particularly to a method for gradually adjusting the height based on a two-axle vehicle air suspension. Background Art

[0002] Air suspensions are widely used in new energy vehicles. Their comfort and height adjustability have become a highlight of new energy vehicles. The front and rear axles of the vehicle air suspension system adopt different hardware structures, so the rising and falling rates are different; in addition, since all four air suspensions are connected to the central air pump, air storage tank and controller assembly through pipelines, only inflation or deflation can be carried out at the same time. To ensure the stability and accuracy of the height adjustment of the air suspension system, the heights of the front and rear axles cannot be adjusted simultaneously, so as to avoid the uncontrollable consequence of the height change rate of the four suspensions rising and falling simultaneously caused by the hardware characteristics. In addition, when adjusting the height, to ensure the comfort of passengers, the body posture should meet the requirement that the front axle is not higher than the rear axle, and the height difference between the front and rear axles should not be too large, that is, to avoid the appearance of a large pitch angle.

[0003] In summary, the height adjustment of the vehicle suspension system needs to be based on three principles: the heights of the front and rear axles cannot be adjusted simultaneously, the front axle is not higher than the rear axle, and the height difference between the front and rear axles should not be too large. Then, for vehicles with a large target height span, the vehicle air suspension system needs to adopt a height step-by-step adjustment technology, and the front and rear axles are adjusted alternately multiple times to reach the target height.

[0004] The currently existing height step-by-step adjustment method takes evenly distributing the overall height span as the core logic. When it is judged that the span of the height adjustment is greater than the set threshold, the adjustment span is evenly divided into the least number of parts so that each part is less than the threshold. As for the adjustment span, it can be calculated by the difference between the average value of the heights of the four suspensions and the target height.

[0005] The advantage of the step - by - step adjustment method mentioned above is that it evenly distributes the height of each level, so that the pitching of the vehicle body can be ensured at a similar angle during the entire height adjustment process, improving the comfort of passengers. However, its deficiency lies in the lack of detailed discussion on the calculation of the overall height span. For the calculation of the target height of each level of step - by - step adjustment, determining the initial state is the primary task, and different initial height states and different front - and - rear axle heights will affect the overall height span. For example, using the average value of the four suspension heights as the reference height ignores the influence of individual suspension heights with large deviations (such as large height differences caused by significant changes in load) on the calculation of the overall height span. In the case where the difference between the front and rear axle heights of the initial height is large, the calculated target height of the first level may be between the front and rear axle heights, causing one of the axles to adjust in the opposite direction during the first - level height adjustment, which needs to be avoided. In addition, different initial height states will also affect the order of front - and - rear axle adjustment, which needs to be discussed in detail, and this is also the lack of the existing technology currently. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a step - by - step height adjustment method for the air suspension of a two - axle vehicle, that is, it evenly distributes the height of each level and optimizes its deficiencies on this basis, that is, it makes a detailed discussion on the initial height state, making the step - by - step height adjustment method introduced in this patent more rigorous, more general, and applicable to various vehicle models and various initial height states.

[0007] The technical solution adopted by the present invention to solve its technical problems is: to provide a step - by - step height adjustment method for the air suspension of a two - axle vehicle, including the following specific steps:

[0008] S1: First, record that the height difference between the front and rear axles during the adjustment process shall not be greater than the threshold value T 跨度 , to meet the height adjustment principle, generally speaking, when rising, the rear axle should be raised first and then the front axle, and when descending, the front axle should be lowered first and then the rear axle. There may be some special initial height states that do not meet the usual front - and - rear axle adjustment order;

[0009] S2: Read the values of the height sensors of the four suspensions in real time, and calculate the heights of the front axle and the rear axle respectively through the following formula:

[0010] H 前轴 =(h 左前 +h 右前 ) / 2

[0011] H 后轴 =(h 左后 +h 右后 ) / 2

[0012] S3: When receiving a new target height, before adjusting the height, compare the relationship between the front axle height, the rear axle height and the target height. For the convenience of the following description, the target height is recorded as H 目标 .H 前轴 , H 后轴 and H 目标 The arrangement can be divided into 6 cases, corresponding to different calculation methods of step-by-step adjustment of target height:

[0013] S3: When receiving a new target height, before adjusting the height, compare the relationship between the front axle height, the rear axle height and the target height. For the convenience of the following description, the target height is recorded as H 目标 .H 前轴 , H 后轴 and H 目标 The arrangement can be divided into 6 cases, corresponding to different calculation methods of step-by-step adjustment of target height:

[0014] When H 前轴 >H 目标 >H 后轴 When the front and rear axles are at the same height, the initial heights are on both sides of the target height. The two axles need to be adjusted in opposite directions to reach the target height. During the adjustment process, the height difference between the front and rear axles will decrease. Therefore, there is no need to adjust step by step. One adjustment will be enough.

[0015] When H 后轴 >H 目标 >H 前轴 This situation is equivalent to the initial height of the front and rear axles being on both sides of the target height, which is similar to the first situation and does not require step-by-step adjustment;

[0016] When H 后轴 >H 前轴 >H 目标 First, calculate the total number of levels that need to be adjusted using the following formula: Total number of adjustment levels = Ceil (maximum height span / T 跨度 ), where the maximum height span in this case is equal to (H 后轴 -H 目标 ), Ceil is the division operation rounded up to ensure that each level of adjustment height is less than T 跨度 , then the average height of each level of adjustment is calculated by the following formula: Each level height = maximum height span / total number of adjustment levels, so the calculation formula for the temporary target height of the nth level is as follows: Temporary target height = H 后轴 -n*each level of height, 1<=n<=total number of adjustment levels. Next, we need to further discuss the special initial height state, that is, whether it satisfies: temporary target height>H 前轴If the above inequality is satisfied, in order not to adjust in the reverse direction, the height adjustment of the current stage should only lower the rear axle, and there is no action instruction for the front axle; if the above inequality is not satisfied, then according to the three principles of air suspension height adjustment, the current stage should first lower the front axle and then lower the rear axle to reach the temporary target height, and repeat the above adjustment method until both the front and rear axles are adjusted to H 目标 ;

[0017] When H 前轴 >H 后轴 >H 目标 , generally, the calculation method and height adjustment method are similar to the third case, and the differences are as follows: Difference 1: The maximum height span is (H 前轴 -H 目标 ); Difference 2: The temporary target height of the nth stage is: Temporary target height = H 前轴 -n * height of each stage. Difference 3: Discuss whether the initial height state satisfies: Temporary target height > H 后轴 . If the above inequality is satisfied, in order not to adjust in the reverse direction, the height adjustment of the current stage should only lower the front axle, and there is no action instruction for the rear axle; if the above inequality is not satisfied, then according to the three principles of air suspension height adjustment, the current stage should first lower the front axle and then lower the rear axle to reach the temporary target height;

[0018] When H 目标 >H 后轴 >H 前轴 , generally, the calculation method and height adjustment method are similar to the third case, and the differences are as follows: Difference 1: The maximum height span is (H 目标 -H 前轴 ); Difference 2: The temporary target height of the nth stage is: Temporary target height = H 前轴 +n * height of each stage; Difference 3: Discuss whether the initial height state satisfies: Temporary target height < H 后轴 . If the above inequality is satisfied, in order not to adjust in the reverse direction, the height adjustment of the current stage should only raise the front axle, and there is no action instruction for the rear axle; if the above inequality is not satisfied, then according to the three principles of air suspension height adjustment, the current stage should first raise the rear axle and then raise the front axle to reach the temporary target height;

[0019] When H 目标 >H 前轴 >H 后轴 , generally, the calculation method and height adjustment method are similar to the third case, and the differences are as follows. Difference 1: The maximum height span is (H 目标 -H 后轴 ); Difference 2: The temporary target height of the nth stage is: Temporary target height = H 后轴+n * height of each level. Third difference: Discuss whether the initial height state meets the condition: temporary target height < H 前轴 , if the above inequality is satisfied, in order not to adjust in the reverse direction, the height adjustment of the current level should only raise the rear axle, and there is no action instruction for the front axle; if the above inequality is not satisfied, then according to the three principles of air suspension height adjustment, the current level should first raise the rear axle and then raise the front axle to reach the temporary target height.

[0020] As a supplement to this technical solution, the discussion of the six initial height states all uses ">", without "=", because the signals received by the software are floating-point types, and the equal sign judgment is meaningless. However, it is also okay to add "=" to some judgment conditions during the software writing process.

[0021] As a supplement to this technical solution, the temporary target height of each level of step-by-step adjustment is calculated according to the following formula:

[0022] Total number of adjustment levels = Ceil(Maximum height span / T 跨度 )

[0023] Height of each level = Maximum height span / Total number of adjustment levels

[0024] Temporary target height = H ± n * Height of each level

[0025] 1 <= n <= Total number of adjustment levels.

[0026] As a supplement to this technical solution, after calculating the temporary target height, further discuss the relationship between the temporary target height and the heights of the front and rear axles to ensure that the adjustment of the current level cannot adjust a certain axle in the reverse direction.

[0027] Beneficial effects: The present invention relates to a method for step-by-step height adjustment of an air suspension based on a two-axle vehicle. By discussing the relationship between the initial states of the front and rear axle heights and the target height, various initial states are summarized, and an algorithm for the temporary target height of each level of step-by-step adjustment of the suspension height under different initial conditions is given, so that the algorithm can cover all initial height states and target heights of the front and rear axles and can be applied to different vehicle models; this patent makes up for the lack in the existing technology of calculating the step-by-step target height based on the initial height state and discussing the adjustment sequence of the front and rear axles. Description of the Drawings

[0028] Figure 1 is the flowchart of the present invention. Detailed Embodiments

[0029] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0030] An embodiment of the present invention relates to a method for gradually adjusting the height based on a two-axis vehicle air suspension, including the following specific steps:

[0031] S1: First, record that the height difference between the front and rear axles during the adjustment process shall not be greater than the threshold T 跨度 , to meet the height adjustment principle. Generally speaking, when rising, the rear axle should be raised first and then the front axle, and when descending, the front axle should be lowered first and then the rear axle. There may be some special initial height states that do not meet the normal front and rear axle adjustment sequence;

[0032] S2: Read the values of the height sensors of the four suspensions in real time, and calculate the heights of the front axle and the rear axle respectively through the following formula:

[0033] H 前轴 =(h 左前 +h 右前 ) / 2

[0034] H 后轴 =(h 左后 +h 右后 ) / 2

[0035] S3: When a new target height is received, before performing height adjustment, compare the relationship between the front axle height, the rear axle height and the target height. For the sake of simplicity in the following description, denote the target height as H 目标 . H 前轴 , H 后轴 and H 目标 can be arranged in 6 cases, respectively corresponding to different calculation methods for gradually adjusting the target height:

[0036] S3: When a new target height is received, before performing height adjustment, compare the relationship between the front axle height, the rear axle height and the target height. For the sake of simplicity in the following description, denote the target height as H 目标 . H 前轴 , H 后轴 and H 目标 can be arranged in 6 cases, respectively corresponding to different calculation methods for gradually adjusting the target height:

[0037] When H 前轴 >H 目标 >H 后轴When this is the case, it is equivalent to the initial heights of the front and rear axles being on both sides of the target height. To adjust the two axles to the target height, they need to be adjusted in opposite directions. During the adjustment process, the height difference between the front and rear axles will decrease. Therefore, there is no need for step-by-step adjustment, that is, one adjustment is sufficient to reach the position.

[0038] When H 后轴 >H 目标 >H 前轴 When this is the case, it is equivalent to the initial heights of the front and rear axles being on both sides of the target height. Similar to the first case, there is no need for step-by-step adjustment either.

[0039] When H 后轴 >H 前轴 >H 目标 When this is the case, first, calculate the total number of adjustment levels required using the following formula: Total adjustment levels = Ceil(Maximum height span / T 跨度 ), where the maximum height span in this case is equal to (H 后轴 - H 目标 ), and Ceil is the ceiling function for division to ensure that the height adjustment for each level is less than T 跨度 . Then, calculate the height adjustment for each level using the following formula: Height per level = Maximum height span / Total adjustment levels. Thus, the formula for the temporary target height at the nth level is as follows: Temporary target height = H 后轴 - n * Height per level, where 1 <= n <= Total adjustment levels. Next, it is necessary to further discuss the special initial height state, that is, whether it satisfies: Temporary target height > H 前轴 . If the above inequality is satisfied, in order not to adjust in the opposite direction, the height adjustment for the current level should only lower the rear axle, and there is no action instruction for the front axle. If the above inequality is not satisfied, then according to the three principles of air suspension height adjustment, the front axle should be lowered first and then the rear axle for the current level to reach the temporary target height. Repeat the above adjustment method until both the front and rear axles are adjusted to H 目标 ;

[0040] When H 前轴 >H 后轴 >H 目标 When this is the case, generally, the calculation method and height adjustment method are similar to those in the third case. The differences are as follows: Difference one: The maximum height span is (H 前轴 - H 目标 ); Difference two: The temporary target height at the nth level is: Temporary target height = H 前轴 - n * Height per level. Difference three: Discuss whether the initial height state satisfies: Temporary target height > H 后轴, if the above inequality is satisfied, in order not to adjust in the reverse direction, the height adjustment of the current stage should only lower the front axle, and there is no action instruction for the rear axle; if the above inequality is not satisfied, then according to the three principles of air suspension height adjustment, the current stage should first lower the front axle and then lower the rear axle to reach the temporary target height;

[0041] When H 目标 >H 后轴 >H 前轴 , generally, the calculation method and height adjustment method are similar to the third case, and the differences are as follows: Difference 1: The maximum height span is (H 目标 -H 前轴 ); Difference 2: The temporary target height of the nth stage is: Temporary target height = H 前轴 +n * height of each stage; Difference 3: Discuss whether the initial height state satisfies: Temporary target height < H 后轴 , if the above inequality is satisfied, in order not to adjust in the reverse direction, the height adjustment of the current stage should only raise the front axle, and there is no action instruction for the rear axle; if the above inequality is not satisfied, then according to the three principles of air suspension height adjustment, the current stage should first raise the rear axle and then raise the front axle to reach the temporary target height;

[0042] When H 目标 >H 前轴 >H 后轴 , generally, the calculation method and height adjustment method are similar to the third case, and the differences are as follows. Difference 1: The maximum height span is (H 目标 -H 后轴 ); Difference 2: The temporary target height of the nth stage is: Temporary target height = H 后轴 +n * height of each stage, Difference 3: Discuss whether the initial height state satisfies: Temporary target height < H 前轴 , if the above inequality is satisfied, in order not to adjust in the reverse direction, the height adjustment of the current stage should only raise the rear axle, and there is no action instruction for the front axle; if the above inequality is not satisfied, then according to the three principles of air suspension height adjustment, the current stage should first raise the rear axle and then raise the front axle to reach the temporary target height.

[0043] As a supplement to this technical solution, the discussion of the six initial height states all uses ">", without "=", because the signals received by the software are of floating-point type, and the equal sign judgment is meaningless. However, in the process of software writing, it is also okay to add "=" to some judgment conditions.

[0044] As a supplement to this technical solution, the temporary target height of each stage of step-by-step adjustment is calculated according to the following formula:

[0045] Total number of adjustment stages = Ceil(Maximum height span / T跨度 )

[0046] Height of each level = Maximum height span / Total number of adjustment levels

[0047] Temporary target height = H ± n * Height of each level

[0048] 1 <= n <= Total number of adjustment levels.

[0049] As a supplement to this technical solution, after calculating the temporary target height, further discuss the relationship between the temporary target height and the front and rear axle heights to ensure that the adjustment of the current level cannot adjust a certain axle in the opposite direction.

Claims

1. A method for adjusting the height of a two-axle automobile air suspension step by step, characterized in that: The specific steps include: S1: First, remember that the height difference between the front and rear axles cannot be greater than the threshold value T during the adjustment process. 跨度 ,To meet the height adjustment principle, generally speaking, when rising, the rear axle should be raised first and then the front axle, and when descending, the front axle should be lowered first and then the rear axle. There are some special initial height states that may not meet the usual front and rear axle adjustment order; S2: Read the values ​​of the height sensors of the four suspensions in real time, and calculate the heights of the front and rear axles respectively using the following formula: H 前轴 =(h 左前 +h 右前 ) / 2 S3: When receiving a new target height, before adjusting the height, compare the relationship between the front axle height, the rear axle height and the target height. For the convenience of the following description, the target height is recorded as H 目标 .H 前轴 , H 后轴 and H 目标 The arrangement can be divided into 6 cases, corresponding to different calculation methods of step-by-step adjustment of target height: When H 前轴 >H 目标 >H 后轴 When the front and rear axles are at the same height, the initial heights are on both sides of the target height. The two axles need to be adjusted in opposite directions to reach the target height. During the adjustment process, the height difference between the front and rear axles will decrease. Therefore, there is no need to adjust step by step. One adjustment will be enough. When H 后轴 >H 目标 >H 前轴 This situation is equivalent to the initial height of the front and rear axles being on both sides of the target height, which is similar to the first situation and does not require step-by-step adjustment; When H 后轴 >H 前轴 >H 目标 First, calculate the total number of levels that need to be adjusted using the following formula: Total number of adjustment levels = Ceil (maximum height span / T 跨度 ), where the maximum height span in this case is equal to (H 后轴 -H 目标 ), Ceil is the division operation rounded up to ensure that each level of adjustment height is less than T 跨度 , then the average height of each level of adjustment is calculated by the following formula: Each level height = maximum height span / total number of adjustment levels, so the calculation formula for the temporary target height of the nth level is as follows: Temporary target height = H 后轴 -n*each level of height, 1<=n<=total number of adjustment levels. Next, we need to further discuss the special initial height state, that is, whether it satisfies: temporary target height>H 前轴 If the above inequality is satisfied, in order not to adjust in the opposite direction, the current level of height adjustment should only lower the rear axle, and the front axle has no action command; if the above inequality is not satisfied, then according to the three principles of air suspension height adjustment, the current level should first lower the front axle and then the rear axle to reach the temporary target height, and repeat the above adjustment method until both the front and rear axles are adjusted to H. 目标 ; When H 前轴 >H 后轴 >H 目标 When the calculation method and height adjustment method are generally similar to the third case, the differences are as follows: Difference 1: The maximum height span is (H 前轴 -H 目标 ); Difference 2: The temporary target height of the nth level is: temporary target height = H 前轴 -n*Each level of height, difference three: discuss whether the initial height state satisfies: temporary target height>H 后轴 , if the above inequality is satisfied, in order not to adjust in the opposite direction, the current level of height adjustment should only lower the front axle, and the rear axle has no action command; if the above inequality is not satisfied, then according to the three principles of air suspension height adjustment, the current level should first lower the front axle and then lower the rear axle to reach the temporary target height; When H 目标 >H 后轴 >H 前轴 When the calculation method and height adjustment method are generally similar to the third case, the differences are as follows: Difference 1: The maximum height span is (H 目标 -H 前轴 ); Difference 2: The temporary target height of the nth level is: temporary target height = H 前轴 +n*each level height; Difference 3: Discuss whether the initial height state meets: temporary target height <H 后轴 , if the above inequality is satisfied, in order not to adjust in the opposite direction, the current level of height adjustment should only raise the front axle, and the rear axle has no action command; if the above inequality is not satisfied, then according to the three principles of air suspension height adjustment, the current level should first raise the rear axle and then the front axle to reach the temporary target height; When H 目标 >H 前轴 >H 后轴 When the calculation method and height adjustment method are similar to the third case, the differences are as follows: Difference 1: The maximum height span is (H 目标 -H 后轴 ); Difference 2: The temporary target height of the nth level is: temporary target height = H 后轴 +n*Each level of height, difference three: discuss whether the initial height state meets: temporary target height <H 前轴 If the above inequality is satisfied, in order not to adjust in the opposite direction, the current level of height adjustment should only raise the rear axle, and the front axle has no action command; if the above inequality is not satisfied, then according to the three principles of air suspension height adjustment, the current level should first raise the rear axle and then the front axle to reach the temporary target height.

2. A step-by-step height adjustment method based on a two-axle automobile air suspension according to claim 1, characterized in that: The discussion of the six initial altitude states all uses ">" instead of "=" because the signal received by the software is of floating point type and the equal sign judgment is meaningless. However, when writing software, there is no problem in adding "=" to some judgment conditions.

3. The method for adjusting the height step by step based on the air suspension of a two-axle vehicle according to claim 1, characterized in that: Height adjustment is based on three principles: the height of the front and rear axles cannot be adjusted at the same time, the front axle is not higher than the rear axle, and the height difference between the front and rear axles should not be too large.

4. The method for adjusting the height step by step based on the air suspension of a two-axle vehicle according to claim 1 is characterized in that: The temporary target height of each step-by-step adjustment is calculated according to the following formula: Total adjustment level = Ceil (maximum height span / T 跨度 ) Each level height = maximum height span / total number of adjustment levels Temporary target altitude = H ± n * each level altitude 1<=n<=total number of adjustment levels.

5. The method for adjusting the height step by step based on the air suspension of a two-axle vehicle according to claim 1, characterized in that: After calculating the temporary target height, we further discuss the relationship between the temporary target height and the height of the front and rear axles to ensure that the current level of adjustment cannot adjust a certain axis in the opposite direction.

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