System for monitoring tire status

• US 6,304,802 B1
• Filed: 09/21/1999
• Issued: 10/16/2001
• Est. Priority Date: 03/22/1997
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Stuible, Ewald, Berger, Walter, Pfau, Martin
• Primary Examiner(s): Nguyen, Tan
• Assistant Examiner(s): TRAN, DALENA
• Application Number:
  US09/381,459
• Time in Patent Office: 756 Days
• Field of Search: 701/75, 701/76, 701/92, 303/122, 303/122.01, 303/122.03, 303/169, 340/442, 340/444
• US Class Current: 701/29
• CPC Class Codes: B60C 23/061 by monitoring wheel speed measuring distance traversed on the ground by vehicles G01C22/00
• CPC Class Codes: B60T 2240/08 Spare wheel detection; Adjusting brake control in case of spare wheel use
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence

Abstract

The invention proceeds from a system for detecting a condition of the wheels of a motor vehicle. For this purpose, means are provided for generating rpm signals, which represent the rotational movements of the wheels, and evaluation means, by means of which a signal is outputted in dependence upon the generated signals, which signal represents the display-relevant condition. The essence of the invention is that the evaluation means are so configured that, first, and dependent upon the generated rpm signals, first difference values are formed for the rpm differences of at least two vehicle wheels on the two sides of the vehicle. Depending upon a first comparison of the formed difference values to each other and/or to pregivable first threshold values, the signal, which represents a display-relevant condition, is outputted. With the invention, one obtains a very simple and cost-effective wheel condition detection (emergency wheel detection, tire air loss detection) which operates correctly also when the vehicle drives through a curve.

Claims

1. A system for outputting a signal representing a condition of the wheels of a motor vehicle, the system comprising:

means for generating rpm signals (Nij) representing the rotational movements of the wheels; and

,

evaluation means functioning to;

form first difference values (Δ

r, Δ

l) for the rpm differences of at least two vehicle wheels on the two sides of the vehicle in dependence upon said generated rpm signals (Nij);

compare the first difference value (Δ

r) of one side of said vehicle to a first adequately large threshold value (SW1);

compare the first difference value (Δ

l) of the other side of said vehicle to a first small threshold value (SW2); and

,

output a signal (S;

Sij) when all of the following conditions are satisfied;

(a) the first difference value (Δ

r) of said one side of said vehicle exceeds said first adequately large threshold value (SW1);

(b) the first difference value (Δ

l) of said other side of said vehicle is less than said first small threshold value (SW2); and

, (c) said first difference value (Δ

r) exceeds said first adequately large threshold value (SWl) simultaneously with said first difference value (Δ

l) being less than said first small threshold value (SW2).

2. The system of claim 1, wherein the evaluation means is so configured that, in dependence upon the generated rpm signals (Nij), second difference values (Δ

h, Δ

v) for the rpm differences of at least two vehicle wheels in the rearward and the forward vehicle region are formed; and

, the signal (S;

Sij) is only outputted when the difference (Δ

vh) of the second difference values is located within a band determined by pregivable second threshold values (Δ

vh_min, Δ

vh_max).

3. The system of claim 2, wherein the evaluation means is so configured that, in dependence upon the generated rpm signals (Nij), second difference values (Δ

h, Δ

v) are formed for the rpm differences of at least two vehicle wheels in the rearward and forward vehicle region; and

, the signal (S;

Sij) is only outputted when the difference (Δ

vh) of the second difference values is located within a band, which is determined by pregivable second threshold values (Δ

vh_min, Δ

vh_max) with the signal (Sij) further being dependent upon;

a third comparison of the rpm signals (Nij) of the wheels on the right vehicle side and a third comparison of the rpm signals (Nij) of the wheels on the left vehicle side; and

,

a fourth comparison of the second difference values (Δ

h, Δ

v) to each other.

4. The system of claim 2, wherein the signal (S;

Sij) is only outputted when the display-relevant condition is detected for the duration of a pregiven time span.

5. The system of claim 2, wherein said evaluation means is so configured that the signal (S;

Sij) is outputted when the formed first difference values (Δ

r, Δ

l) both exceed a pregivable third threshold value (SW3).

6. The system of claim 5, wherein at least one of said first, second and third threshold values are pregiven in dependence upon a value representing the vehicle longitudinal speed.

7. The system of claim 2, further comprising at least one of the following:

display means for displaying a display-relevant condition to the driver of said vehicle by driving the display means with said signal (S;

Sij); and

, a braking system and/or a drive control system having an operating state changed in dependence upon said outputted signal (S;

Sij).

8. The system of claim 1, wherein said condition includes at least one of the following:

a first condition wherein a wheel has a lesser diameter than the remaining wheels and a second condition wherein a loss of air has occurred in a tire of a wheel.