Method for monitoring a state of wear of a damping device

Abstract

The invention relates to a method for monitoring a state of wear of a damping device within a system. The system includes a vehicle seat having a first portion which is movably mounted in at least one direction with respect to a second portion, a damping device for damping oscillations is arranged between the first portion and the second portion, and a first sensor that determines an instantaneous relative position of the first portion with respect to the second portion. A displacement function in relation to the relative position of the first portion with respect to the second portion is defined as a function of time, and a current value of the displacement function is determined at selected intervals and summed. The sum is compared with a predetermined first limit.

Claims

1. A method for monitoring a state of wear of a damping device within a system, the system comprising: a vehicle seat having a first portion, which is mounted movably in at least one direction relative to a second portion; a damping device, wherein the damping device is arranged between the first portion and the second portions; a first sensor, wherein the first sensor determines an instantaneous position of the first portion relative to the second portion, wherein the method includes: using the first sensor, obtaining a position value for the position of the first portion with respect to the second portion at different points in time; determining a sum of all of the obtained position values; comparing the sum with a predetermined first limit; and in response to determining that the sum is greater than the predetermined first limit, outputting a message recommending replacement of the damping device.

2. The method according to claim 1, wherein a displacement function is selected from a relative position, a velocity, a product of the relative position and the velocity and an acceleration in each case of the first portion relative to the second portion.

3. The method according to claim 1, wherein a second sensor in the form of a temperature sensor is provided, wherein the method further comprises: detecting a current temperature of the damping device, comparing the current temperature of the damping device with a predetermined temperature limit, if the comparison results in the temperature being higher than the predetermined temperature limit: determining a respective quotient of the predetermined first limit and a predetermined correction factor with a value greater than 1, and setting the determined quotient as the predetermined first limit for the comparison.

4. The method according to claim 1, wherein the message is output as a visual message via a display.

5. The method according to claim 1, wherein the message is output as an acoustic message.

6. The method according to claim 1, wherein the message is output as a fault code provided to a vehicle control unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Advantages and expediencies can be found in the following description in conjunction with the drawings.

(2) In the drawings:

(3) FIG. 1a is a perspective view of a vehicle seat;

(4) FIG. 1b is a schematic representation of a scissor frame of the vehicle seat according to FIG. 1a;

(5) FIG. 2a is a graph showing an exemplary course of the displacement function;

(6) FIG. 2b is a section of another graph showing an exemplary course of the displacement function;

(7) FIG. 3 is a flowchart showing a preferred sequence of the method.

(8) FIG. 1a shows a system S and more precisely a vehicle seat 1 having a backrest RL, a seat portion ST and an armrest AL. A first portion 2 (upper portion) of the vehicle seat 1 is oscillatory mounted with respect to a second portion 3 (lower portion) of the vehicle seat 1 by means of a vertical oscillation arrangement in the form of a scissor frame 6.

(9) FIG. 1b schematically shows the system based on this scissor frame 6, on which a pneumatic spring 7 and a damping device 4 in the form of a hydraulic damper are arranged in each case between the first 2 and the second portion 3. In this case, a first part 41 of the damping device 4 in the form of a piston is attached to the first part 2 of the vehicle seat 1 and a second part 42 of the damping device 4 in the form of a cylinder is attached to the second part 3 of the vehicle seat 1, wherein the first part 41 and the second part 42 of the damping device 4 are arranged so as to be movable relative to one another.

(10) In the present case, the system S thus comprises the vehicle seat 1 having a first portion 2, which is movably mounted with respect to a second portion 3 in at least one direction 1z, wherein the damping device 4 is arranged for damping oscillations between the first portion 2 and the second portion 3, and further a first sensor 5 for determining an instantaneous relative position (see also FIG. 2b) of the first portion 2 with respect to the second portion 3 in relation to a predetermined initial relative position x0.

(11) In the present case, the first sensor 5 is configured by a rotation angle sensor arranged at the central pivot point 60 of the scissor frame 6.

(12) In the present case, the initial relative position x0 is defined as the distance in direction 1z between the first portion 2 and the second portion 3 in an undeflected position of the scissor frame, which may be defined, for example, in that the guide rollers of the floating bearings 81 (see FIG. 1b, arranged in each case on the left of the first portion 2 and the second portion 3) being in a central position in relation to a width direction 1y. In addition, locating bearings 82 are arranged in each case on the right of the first portion 2 and the second portion 3.

(13) In the present case, a higher-level control unit CU is provided, which carries out the determination of the data, the comparison and a message. It receives the data from the first 5 and also from the second sensor 51 and, if necessary, forwards a signal to a display device 9, whereupon the display device 9 transmits a visual and/or acoustic message to the driver.

(14) The second sensor 51 is arranged in the present case on the outside of the damping device 4 and is configured in the form of a temperature sensor.

(15) FIGS. 2a and 2b show by way of example the course of a displacement function x, v, xv, a of the first portion 2 with respect to the second portion 3 over time t. Since the graph shown could represent all the possible displacement functions x, v, xv, a, all the displacement functions x, v, xv, a are marked. Relevant for the present method 100 is the determination of the hatched area, i.e. the integral of the displacement function x, v, xv, a over the time t. This integral corresponds to one of the sums Σ1, Σ2, Σ3 or Σ4.

(16) FIG. 2b again illustrates the basic idea of integral calculus using the example of arbitrarily selected points in time t1 to t6, according to which the hatched area between the function graph and the t-axis can be divided into a large number of narrow rectangles, as is well known, wherein the bases of all the rectangles lie on the t-axis and the heights of the rectangles are given by the current values x1 to x6 at the respective points t1 to t6. In this case, a base has a value of the predetermined time integral Δt. While the values x1 to x5 are positive, the value x6 is negative, so that the amount |x6|, which is included in the calculation of the sum Σ1, is also illustrated here.

(17) FIG. 3 shows a preferred sequence of the method 100 for monitoring a state of wear of the damping device 4 within the system S. The method 100 is described in the present case on the basis of the section of the displacement function x (see also FIG. 2b), which describes the relative position x1-x6 of the first portion 2 with respect to the second portion 3 as a function of time t in the time period from t1 to t6. The method 100 has the following method steps:

(18) (101) defining a displacement function x in relation to the relative position x of the first portion 2 with respect to the second portion 3 as a function of time t,

(19) (102) determining a current value x1 of the displacement function x at a first point in time t1,

(20) (103) determining an amount |x1| of the current value x1 of the displacement function x,

(21) (104) repeating the steps (102) and (103) in each case after a certain time interval Δt up to a predeterminable last point in time t6 and thus determining the amounts (|x1|, |x2|, . . . , |x6|) at each point in time (t1, . . . , t6),

(22) (105) determining a sum Σ1 of all the amounts (|x1|, |x2|, . . . , |x6|),

(23) (106) comparing the sum Σ1 with a predetermined first limit xg.

(24) If in step (106) it is noticed that the sum Σ1 is equal to or greater than a predetermined first limit xg, a message is sent to the driver according to step (106b), which may result in replacement of the damping device 4.

(25) If this is not the case, the method 100 in the present example continues at step (102).

(26) Alternatively, the method 100 may comprise further steps after step (106):

(27) (107) detecting a current temperature T of the damping device 4,

(28) (108) comparing the current temperature T of the damping device 4 with a predetermined temperature limit Tg,

(29) (109) if the comparison according to step (109) results in the temperature T being higher than the predetermined temperature limit Tg: determining a respective quotient from the predetermined first limit xg and a predetermined correction factor having a value greater than 1, and setting the determined quotient as the predetermined first limit for the comparison according to step (106).

(30) All the features disclosed in the application documents are claimed as being essential to the invention, either individually or in combination, provided that they are novel over prior art.

LIST OF REFERENCE SIGNS

(31) 1 vehicle seat

(32) 1y width direction

(33) 1z vertical direction

(34) 2, 3 portion

(35) 4 damping device

(36) 5, 51 sensor

(37) 6 scissor frame

(38) 7 spring

(39) 9 display device

(40) 41, 42 part

(41) 81 floating bearing

(42) 82 locating bearing

(43) 100, 200, 300, 400 method

(44) 101, 102, . . . , 109 method step

(45) xg limit

(46) CU control device

(47) S system

(48) t1, . . . , t6 point in time

(49) x0 initial relative position

(50) x1, x2, . . . , x6 relative position

(51) AL armrest

(52) RL backrest

(53) ST seat portion

(54) |x1|, |x2|, . . . , |x6| amount

(55) Σ1, Σ2, Σ3, Σ4 sum