DESC:SYSTEM FOR MONITORING AUTOMOTIVE SUSPENSION
Field of the invention:
The present invention relates to an automotive suspension and more particularly, to a system for monitoring the automotive suspension.
Background of the invention:
A shock absorber is a ride control system used in an automobile vehicle which absorbs spring stored energy and dissipate into heat, hence control the spring oscillation and provides a better ride control and comfort to the rider and/or passenger. The process of converting spring energy to heat energy is called damping. Widely in automobile industries hydraulic shock absorbers are used, where the damping is created by flow control of a hydraulic fluid inside the damper. This type of damping is called viscous damping where fluid viscosity is a dominant factor in deciding the damping forces.
However, in case of the hydraulic damper, any change in flow path due to tear and wear or change in properties of oil due to high operating temperature and pressure will result in loss of the damping property that ultimately affects the ride quality of the vehicle. An excessive drop in the damping characteristics may cause the vehicle to lose the control and eventually creates potential risk of accidents.
It is very critical to monitor the health of shock absorber periodically to make sure that the suspension is performing well. Unfortunately, there are not many testing devices available in the market which can check the suspension health on the vehicle level. Mostly, the shock absorbers are tested as subjective feedback from a driver or technician and may result in inaccurate results.
Though there are some systems available in the market which studies the decay rate of sprung mass system to help to measure the system oscillations decay rate but these systems may not give the desired result for light weight vehicles, over damped systems, and those suspension systems where frictional forces are significant for example, motor cycle and entry segment passenger cars.
Alternatively, the shock absorber is removed from the vehicle and to put into a dyno machine for testing the damping force. However, this process is very time consuming and cost of dyno machines are so high and a normal service center cannot afford the price.
Accordingly, there exists need to provide a system for monitoring an automotive suspension that overcomes the above mentioned drawbacks in the prior art.
Object of the invention:
An object of the present invention is to provide a portable and affordable system that is useful to evaluate the suspension health on a vehicle level.
Summary of the invention
The present invention discloses a system for evaluating suspension health of an automotive vehicle. The system comprises a sensor box having an accelerometer mounted therein, a controller and an electronic computing device. The sensor box is mounted on a vehicle sprung mass just above a vehicle wheel center with which a suspension under test is associated. The accelerometer is a DC single axis accelerometer that detects a compression acceleration and a rebound acceleration of the sprung mass. The controller is in connection with the sensor box for supplying and controlling power supply to the accelerometer. The controller is having a processor configured therein for receiving a signal data from the accelerometer and processing the signal data to convert into a digital format. The signal data includes a compression acceleration data and a rebound acceleration data. The electronic computing device is operably connected to the controller. The electronic computing device includes a processing module, a memory unit and a user display. The processing module is configured to receive the signal data from the controller and evaluate the suspension health. The processing module is adapted to process the compression acceleration data to estimate a Calculated rebound velocity (CRV) corresponding to a master sample, process the rebound acceleration data to estimate an actual rebound velocity (ARV) of the suspension under test, and compare the calculated rebound velocity (CRV) with the actual rebound velocity (ARV) to evaluate the suspension health.
Brief description of the drawings:
The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein
Figure 1 shows a block diagram of a system for monitoring automotive suspension, in accordance with the present invention;
Figure 2 shows sensor box of the system for monitoring automotive suspension, mounted on a test vehicle, in accordance with the present invention;
Figure 3 is a graphical representation of compression stroke vs. rebound velocity, in accordance with an exemplary embodiment the present invention;
Figure 4 is a graphical representation of displacement vs. rebound velocity of two samples, in accordance with an exemplary embodiment the present invention;
Figure 5 and 6 are the observations and graphical representation of displacement vs. rebound velocity of two samples, in accordance with an exemplary embodiment the present invention;
Detailed description of the invention:
The foregoing objects of the invention are accomplished, and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiments.
The present invention provides a system for monitoring automotive suspension. Being portable and affordable, the system is useful to evaluate the suspension health on a vehicle level. The system of the present invention utilizes hardware component that is easily used / mounted on the automobile / vehicle and software component for monitoring shock absorber characteristics and for health checkup thereof.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description and in the table below.
Table:
Ref. No. Component name Ref. No. Component name
10 Accelerometer 40 Controller
20 Sensor box 50 Electronic computing device
30 Processor 60 User display
Referring to figure 1, a system (100) for evaluating health of a suspension of an automotive vehicle, in accordance with the present invention is shown. The system (100) comprises a sensor box (20), a controller (40) and an electronic computing device (50).
The sensor box (20) includes an accelerometer (10) mounted therein. The sensor box (20) is mounted on a vehicle sprung mass just above a wheel center for measuring the sprung mass movement during testing. The sensor box (20) is mounted above the wheel center with which a suspension under test is associated. The accelerometer (10) detects a compression acceleration and a rebound acceleration of the sprung mass on which it is mounted.
The controller (40) is connected to the sensor box (20) for supplying and controlling power supply to the accelerometer (10). The controller (40) includes a processor (30) configured therein for receiving the signal measurement data from the accelerometer (10) in the sensor box (20) and processing the data to convert into a digital format. The signal measurement data includes a compression acceleration data and a rebound acceleration data.
The electronic computing device (50) is operably connected to the controller (40) for receiving the signal measurement data therefrom. The electronic computing device (50) includes a processing module (not shown), a memory unit (not shown) and a display unit (not shown). The memory unit stores a plurality of processing instructions therein. The processing module is configured to receive the signal data from the controller (40) and disposed in communication with the memory unit and configured to issue a plurality of processing instructions stored in the memory unit and evaluate the suspension health. The processing module is adapted to process the compression acceleration data to estimate a calculated rebound velocity (CRV) corresponding to a master sample, process the rebound acceleration data to estimate an actual rebound velocity (ARV) of the suspension under test, and compare the calculated rebound velocity (CRV) with the actual rebound velocity (ARV) to evaluate the suspension health.
The processing module processes the data received from the controller (40), compares the data with a standard value stored in a database and provides the results of comparison. The processing module captures the peak and converts the data into a useful format. Specifically, the output of the algorithm processing includes, but is not limiting to, calculated rebound velocity, measured rebound velocity, results and like. The result is displayed on the display unit (60) of the electronic computing device (50). In an embodiment, the electronic computing device (50) includes any one of desktop computer, laptop, a mobile phone and other devices known in the art. However, it is understood here that any device with a small computing system and a display can also be used in other alternative embodiments of the present invention.
Again referring to figure 1, in an operation, the controller (40) and the electronic device (50) are connected. The sensor box (20) gets powered and starts recording the data. For performing a manual hand press test on the vehicle to measure the suspension response, the vehicle sprung mass of interest is pressed down by hand and released in a predefined time causing the sprung mass to return (rebound) naturally. The return (rebound) of the sprung mass depends on few suspension parameters such as spring stiffness, spring pre-compression, rebound damping force and the like. Also the speed of rebound is more relative to the amount of compression, but not to the speed of compression because rebound is resulted from the spring stored energy during compression. Thereafter, the accelerometer (10) connected to the sprung mass captures the acceleration data, both compression and rebound on the sprung masses. The acceleration data is processed in the electronic device (50) to study the suspension response.
In accordance with the present invention, the data of interest is selected. In the compression stroke, the processing module detects the peak and chooses the span of -0.5 sec to +0.5 sec of the peak data for post processing, and rest of the data is discarded. The processing module thereafter detects the compression stroke by detecting the sign of signal, for example, + ve acceleration for compression and -ve acceleration for rebound. The processing module then performs double integration on the compression stroke acceleration to find maximum displacement of the sprung mass.
In accordance with the present invention, velocity from the acceleration data is expressed as:
v(t)=?a(t)dt+C1
In accordance with the present invention, displacement from derived velocity data is expressed as:
x(t)=?v(t)dt+C2
wherein, a = acceleration, v = velocity, x = displacement, t = time, C1 and C2 considering zero as initial velocity and displacement considering as zero.
Now using derived displacement data, rebound velocity is calculated using the following formula:
y = mx+c
wherein, y = calculated rebound velocity
x = derived compression displacement
m = Slope of linearity curve derived from a master sample testing
c = Offset of linearity curve derived from a master sample testing
m and c are slope and offset respectively of linearity curve derived from a master sample testing. This is defined by a shock absorber manufacturer for model to model and y is displayed as “calculated rebound velocity (CRV)” which will correspond to the master sample data.
In accordance with the present invention, in the rebound stroke, the acceleration value is recorded and a single integration is performed on the data to find the rebound velocity of the sprung mass. Figure 3 shows graphical representation of compression stroke vs. rebound velocity, in accordance with the present invention.
In accordance with the present invention, the velocity from acceleration data is expressed as:
v(t)=?a(t)dt+C1
This is the actual rebound velocity corresponding to the shock absorber mounted on the vehicle and referred as “actual rebound velocity (ARV)”.
In accordance with the present invention, after calculation of Calculated Rebound Velocity (CRV) which corresponds to the master sample or master spec, and Actual Rebound Velocity (ARV) corresponding to the testing sample characteristics, the decision factor is applied as follows:
1. ARV> (1+C) x CRV system is under damped
2. ARV<(1-C) x CRV system is over damped
(C is tolerance factor, for eg: ±15% tolerance range C=0.15)
Experimental data
For the validation purpose, two rear shock absorbers of the Suzuki Gixxer vehicle were selected, details of the shock absorber are as follows,
1. Sample 1: damping force for the sample is close to the mean spec
2. Sample 2: Damping force for the sample is 80% drop in 0.1 m/s and 40% drop in 0.3 m/s velocity from the mean specification
Velocity (m/s) Rebound Damping force
Drawing spec Sample 1 % variation Sample 2 % variation
0.1 1282 1390 8 257 -80
0.3 3369 3351 -1 2025 -40

Referring to figures 5 and 6, the test was conducted on vehicle with different level of input compression for sample 1 and sample 2 respectively. Both the sample data show R2 value above 75% and it’s a good correlation value for the linear equation.
Here difference in measured rebound velocity of sample 1 and sample 2 is clearly seen in all the different shock absorber compression levels. From sample 1 and sample 2 data, a linear equation is created as follows:
Y (velocity)= Mx+C (x=displacement)
M (slope of equation) C (offset)
Sample 1 3.5714 108.66
Sample 2 7.3172 159.73
Thus, the user is able to differentiate a good sample (sample 1) and a bad sample (sample 2) on vehicle level with the system (100). Test results are not affected by the kind of testing, as any amount of compression, system is able to differentiate good and bad sample. Test results have a very good confidence level as R2 value is above 0.75 with multiple testing. For the above testing the damper was considered as single damping coefficeint, however it is understood that the test can be carried out for any system having multiple coefficient for different velocity. Particular M and C can be changed accordingly.
Advantages of the invention:
1. Being portable and affordable, the system is useful to evaluate the suspension health on a vehicle level.
2. The system utilizes hardware component that is easily used on the automobile/vehicle and software components for monitoring shock absorber characteristics and for health checkup thereof.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the scope of the claims of the present invention.
,CLAIMS:We claim:
1. A system (100) for evaluating health of a suspension of an automotive vehicle, the system (100) comprising:
a sensor box (20) having an accelerometer (10) mounted therein, the sensor box (20) being mounted on a vehicle sprung mass just above a vehicle wheel center with which a suspension under test is associated, wherein the accelerometer (10) is adapted for detecting a compression acceleration and a rebound acceleration of the sprung mass when the sprung mass is hand pressed to measure the suspension response;
a controller (40) in connection with the sensor box (20) for supplying and controlling power supply to the accelerometer (10), the controller (40) having a processor (30) configured therein for receiving a signal data from the accelerometer (10) and processing the signal data to convert into a digital format, wherein the signal data includes a compression acceleration data and a rebound acceleration data;
an electronic computing device (50) operably connected to the controller (40), the electronic computing device (50) including a processing module, a memory unit and a user display (60) in communication with each other, the processing module configured to receive the signal data from the controller (40) and evaluate the suspension health, wherein the processing module is adapted to process the compression acceleration data to estimate a calculated rebound velocity (CRV) corresponding to a master sample, process the rebound acceleration data to estimate an actual rebound velocity (ARV) of the suspension under test, and compare the calculated rebound velocity (CRV) with the actual rebound velocity (ARV) to evaluate the suspension health.
2. The system (100) as claimed in claim 1, wherein the accelerometer (10) is a DC single axis accelerometer.
3. The system (100) as claimed in claim 1, wherein the electronic computing and device (50) is any one of a wired and wireless electronic computing and device (50) including a computer, a laptop, a mobile phone.
Dated this on 8th day of March, 2022

Ashwini Kelkar
(Agent for the applicant)
(IN/PA-2461)