Method for regulating a tyre inflating device.

The invention relates to a method according to the preamble of claim 1. Such a method is known from EP 0 019 463 A2. With this method, the air is supplied step by step in constant predetermined time steps until the desired target pressure in the tire is reached. This method has the disadvantage that it may take a relatively long time to reach the desired pressure in the tire to be inflated.

Proceeding from this, the object of the invention is to create a control method in which the time required for filling the tire can be significantly reduced. The aim is to get by with about 2 - 3 filling processes if possible.

This object is achieved by a control method with the features according to the characterizing part of claim 1.

According to this teaching, a so-called test filling process is carried out in a first step and then by comparing the measured pressure increase in the tire with the total pressure increase required, the time interval for the following filling process is determined in such a way that the target pressure theory should already be achieved with the second filling process. In the event that the target pressure should in reality not yet be reached with the second or further filling processes, the next filling process is carried out according to the same principle, but with the initial values ​​after the previous filling process.

Appropriate security measures for the control method according to the invention are the subject of the subclaims.

The safety measure according to claim 2 is about the fact that overfilling of the tire is excluded in the event of a failure of the control device. This is brought about by a retriggerable monoflop, which only allows the closed closure valve at the outlet of the tire inflation device to be opened if it is constantly excited by pulses at predetermined intervals. The time intervals can be set arbitrarily, for example one to two seconds.

The safety measure according to claim 2 is intended to avoid that when the air actually enters the tire from the tire inflation device, if this is not registered due to a defect in the pressure value recording or transmission by the control device, the tire is overfilled.

According to claim 4, this safety measure is refined by the fact that the tire inflation device is also put out of operation if, in the second inflation process, in which the desired target pressure is to be approximately achieved, a change in pressure not at least by the control device of 50-80 K of the value that would be mathematically required to achieve the target pressure is registered.

The measure according to claim 5 provides that in the event of an inadvertently preselected target pressure at a smaller tire which is unsuitable for such pressures, such as, for example, bicycle tires, the tire inflation device is also put out of operation.

An embodiment is shown in the drawing. Show it<ul id="ul0001" list-style="none"><li>Fig. 1 shows the schematic structure of the device required to carry out the control method</li><li>Fig. 2 is a diagram for the geometric representation of the mathematical law of education to determine the time intervals of the tire inflation</li></ul>

In the case of the safety measures described above, it may also be sufficient in some cases that a warning display first appears instead of the tire inflation device being taken out of operation.

1 shows the tire as a controlled system and 2 shows a control device designed as a programmed microprocessor. The tire inflation device 3 is connected to the tire 1 via a closure valve 4 equipped with solenoid valves. The air pressure 5 from a compressed air supply container is applied to the tire inflation device 3. The actual pressure 6 prevailing in the tire 1 is detected by a measuring means 7 and converted into a digital signal of the control device as a variable 8. The actual value on the tire inflation device 3 can also be fed to an actual value display 10 via a line 9. The desired target tire pressure 11 is entered via a target value input device 12 of the control device 2 in addition to the actual tire pressure 6 (size 8).

When the tire inflation device 3 is started up after connection to the tire 1, a first filling process is initiated by the control device 2 by a start signal to be triggered by the operator, while the values ​​for the actual tire pressure 6 and the target pressure 11 are simultaneously from the control device 2 be included. The period for the first filling process is in the control device 2 with dt_O= const permanently stored. For Δ t_OFor example, a value of 500 ms can be specified. The control device 2 determines the time intervals for the following filling processes according to the teaching specified in the characterizing part of patent claim 1. For this purpose, the following educational law has been entered into the control device as a computer program:<maths id="math0001" num=""><img file="EP0133482A2_D0001.tif" /></maths>with i = 1.2₁ ---------- ,<maths id="math0002" num=""><img file="EP0133482A2_D0002.tif" /></maths><maths id="math0003" num=""><img file="EP0133482A2_D0003.tif" /></maths>

The diagram in FIG. 2 illustrates the control steps resulting from the application of the programmed education law, in which the tire pressure p is plotted over the filling time t. The point A at (i-1) indicates the initial condition of the tire after the tire inflator has been connected. The first filling process, a so-called trial shot, takes place in a fixed time interval t = const. It causes an increase in pressure in the tire to point B with the coordinates i. For the second filling process, the control device now uses the law of education to determine the time interval at which the theoretical pressure should theoretically have already been reached with this filling process if the pressure increase per unit of time remains constant. This results in the following time interval<maths id="math0004" num=""><img file="EP0133482A2_D0004.tif" /></maths>In the event that the pressure is actually at the value C with the ordinate p_should the tire is completed. However, this is after Δ t_i in reality not yet given, but rather only the one under p_should If point D is reached, the following new time interval is determined and set for the next filling process<maths id="math0005" num=""><img file="EP0133482A2_D0005.tif" /></maths>

After the following third filling process carried out with this time interval, the pressure value then measured now has the target pressure value p_should reached, the tire is again filled. If the target pressure is still not reached, further filling processes are carried out according to the described pattern until the target pressure is finally reached. As a rule, the target tire pressure is reached after about 2-3 filling processes within the specified accuracy. For example, a tolerance of +/- 0.5 K of the maximum adjustable target pressure can be specified as the tolerance range. The particular advantage of the method according to the invention consists in being able to determine in advance the theoretically required total filling time per filling unit of time with constant pressure increase and to be able to set it for the next filling process. This makes it possible to get by with a minimum of filling processes, which in turn means very quick filling.

The education law described above only applies if the feed pressure is kept constant. If the feed pressure is not constant, as is the case when emptying a relatively small storage container without using a reducing valve, other, non-linear educational laws apply. However, the control procedure is basically the same.

Only the case is described above in which a tire to be inflated has too little pressure and must therefore be inflated . The control procedure naturally also applies to cases in which the tires are to be brought from a high actual pressure to a lower target pressure. In these cases, the first filling process is simply replaced by a first draining process with a predetermined time interval. The following drainage processes are determined by the programmed education law in an analogous way to filling. The only difference is that fill and drain times are not set and set.

The retriggerable monoflop according to claim 2 is entered in Fig. 1 of the drawing under the reference number 13.