Pressure control device for electro-pneumatic vehicle braking systems, especially commercial vehicles

The invention relates to a pressure control device according to the preamble of Claim 1.

In electro-pneumatic braking systems for brake pressure control Actuators of various kinds used. The actuators in these systems must take both the service brake and the ABS function. there apply it for the service brake function both slow, sensitive pressure changes and emergency braking or when ABS function rapid pressure changes to enable. are used valves, which either fulfill both functions may or different valves separately for each function. It come under others apply proportional solenoid valves with and without relay valve, with and without ABS pressure control valves, henceforth double solenoid valves Pilot control of a relay valve, with and without ABS pressure control valves, and current controlled pilot solenoid valves with poppet valves, the latter for both Functions.

While attempting to allow precision adjustments of consumer pressure, Pressure regulating devices have been developed in which at consumer-side Monitoring the consumer pressure by a pressure sensor inlet and Exhaust valves are provided, which cooperate with pilot valves, such that in the course of the electrical drive of the inlet and Exhaust valves actuated electromagnets limited throttled Opening of the pilot valves is possible. With increasing excitation of the Solenoids, the pilot valves are closed and the actual Main valves open large cross sleekly. The desired feed of sensitive Consumer pressure is in such control equipment through a variety of Parameters determined; there are also intermediate or floating positions of where main valves, which may be defined as a function of the excitation current have to. The structural complexity of such pressure control devices is therefore significantly, also function accuracy is at different temperature and Pressure ratios required.

Assuming the object of the invention to provide a Pressure control device of the generic type by simple means so to design to satisfy both service brake and ABS functions can, and is particularly suitable for both sensitive pressure changes in to provide service braking and rapid pressure changes to permit when emergency braking or ABS functions require. Also intended by the design of such pressure control devices using Pilot units be dispensable.

To achieve this object the features used by the characterizing part of Claim 1.

By sensor-dependent activation of the electromagnets of intake and Exhaust and as a result of the precisely defined contouring of the valve piston of Intake and exhaust valves at their upstream end, it is depending on the stroke possible to achieve any specific pressure and volume change to the consumer, ie that by the stroke-dependent change in the available cross-section between The inlet end of the valve piston and inner cross section of the valve piston directly housing receiving the capabilities of the respective braking situation adjusted pressure profile are given. The Luffstrom is therefore targeted by a variable over the piston stroke of the intake and / or exhaust valve Flow cross section to dose. This makes it possible that:<sl><li>in emergency braking the full cross section and thus a rapid increase in pressure is made possible; </li><li>also worked at an ABS control with large cross-sections can;</li><li>small in sensitive braking and slow changes Flow cross sections and thus slow pressure changes are made possible;</li><li>the dynamic variation of the brake signal, for example, rapid increase in pressure to about 90% of the brake pressure and then slowly increase pressure, solely by the Changing the flow cross-section can be realized; and that</li><li>the so-called wheel module of the brake pressure gradient for loading and Vent learned since the downstream volumes of brake hose and Brake cylinder according to the installation will remain constant, so that according to the height and in particular the time dependence of the brake signal an optimum rules is made possible.</li></sl>

Regarding the structural criteria of such pressure control device, so are likewise significant advantages achievable, ie both the service brake function as the ABS function can be realized with a module that henceforth there Air consumption as in current braking systems, ie no increased air consumption by clocking valves. It must be accepted, they are silent, as in occur stroke valves or pulsating valves adversely. It is also advantageous that the device by its current control substantially temperature-independent working.

Advantageous refinements and developments are in another Claims listed.

The invention is described below with reference to exemplary embodiments Reference to the accompanying drawings explained.<sl><li>Fig. 1 is a schematic view of the pressure control device according to the invention; </li><li>FIG. 2 are enlarged sectional views of three different contours, formed between the inlet end of the valve piston and the inner cross-section of the Valve end of the female housing, again;</li><li>Fig. 3 shows the achievable by means of the contours A, B and C according to Figure 2 Flow cross sections Q1-Q3 compared to the stroke S again, said with Sr Control range of available stroke is shown; and</li><li>Fig. 4 is a FIG. 1 similar schematic view of a Pressure control device according to a further embodiment of the invention, under Using a pneumatically-redundant system.</li></sl>

In Fig. 1 of the drawings is a first embodiment of an electropneumatic Brake system using the pressure control device 1 shown. The pressure control device 1 is located in manner shown in Switching to a compressed air supply 3, a brake cylinder 5 for a schematic reproduced wheel 7 of the vehicle and an electro-pneumatic Brake signal transmitter 9 in the form of a foot brake. The pressure control device 1 consists of two functional units, a schematically reproduced, electronic control unit 11, and a valve device 13, which in below the manner explained controlled by the electronic control unit is to make the connection between the pressure medium source, so the compressed air supply 3, and the consumer, ie, the brake cylinder 5, and the connection between the brake cylinder 5 and the pressure relief, ie in the illustrated Embodiment with the outside air to control.

The electro-pneumatic brake signal transmitter 9 with its electrical part on a control line 15 and a connector 17 to the electronic control unit 11 connected. The electronic control unit 11 is located within a Housing 19, which with the housing underneath the drawing 21 the valve device 13 is connected; in the housing 19 of the electronic Control unit are an electromagnet 23 with one of its anchor formed actuating ram 25, another electromagnet 27 with a Actuating plunger 29 and a connected to the electronic control unit 11 Pressure sensor 31. The two electromagnets 23 and 27 are also the are electronic control unit 11 is connected, and in accordance with the Actuating the brake signal transmitter 9 and converted by the pressure sensor, in the electronic control unit 11 incoming variables controlled. In below the Housing 19 located housing 21 is the valve means 13 with a Inlet valve 33 and an exhaust valve 35 is provided. The inlet valve monitors the Communication between an inlet 37 and a fluid chamber 39, which via an outlet 41 to the consumer, that is connected to the brake cylinder 5 is. The outlet valve 35 monitors the connection between the load 5 and a further outlet 43, which is connected to the atmosphere, ie the actual relief device forms. is in the embodiment shown the outlet 43 with the outside air via a muffler 45 compound. In the representation of FIG. 1, the two valves in their initial position reproduced, that is, the inlet valve 33 closes the connection between the Compressed air supply 3 and the load, while the outlet valve in the connection Direction vent releases, ie, the brakes of the vehicle are vented. The two electromagnets are de-energized, the retracted position of the Actuating plunger 25 and the extended position of the actuating plunger 29 as are brought under spring action.

The inlet valve 33 is provided with a valve piston 47, which against the force a spring 49 and can be actuated in a conventional manner means for pressure relief which means in the embodiment shown holes, which by itself the valve piston extends, in such a way that on both end sides of the valve piston Pressure relief is.

In the inventive manner, the valve piston 47 is in its immediate Inlet region, ie at its end facing the supply pressure of a special contour design provided, which allows the air flow targeted to dose by a variable piston stroke over the flow cross section. The special shape of the inlet end of the valve piston 47 is a adapted contouring at the inlet cross section of the valve casing, so that between Valve housing inner periphery and outer periphery of the valve piston 47, the aforementioned specific air dosage is provided in accordance with the stroke. FIG. 2 the drawing are various contours at the inlet end of the valve piston 47 in Assignment to specially designed contour of the valve housing reproduced. illustrates Fig. 3 of the drawing, in accordance with that shown in Fig. 2 contourings illustrated enabled flow cross sections depending the stroke of the slide from the actuating plunger 25 the valve piston. The Flow cross-sections Q1, Q2, and Q3 of Fig. 3 are the contours A, B and C assigned in FIG. 2. It can be seen that the contour of A to a linear extending change in the flow cross-section leads, while the contour B function of the stroke a complete opening of the cross section with the prior linear cross-sectional enlargement triggers. If the contour C the profile is between Valve piston 47 and the valve housing of different types, ie the arcuate profile at the inlet end of the valve stem corresponds to that in Fig. 3 reproduced arcuate course of the flow cross section, which is formed between the valve body and the inlet end of the valve piston.

The above explanation regarding the changes in cross section at the valve piston 47 of the intake valve 33 are in the same way for contouring and viewed deriving therefrom changes in cross section at the valve piston 50 of the exhaust valve 35 valid. Also, the actuation of the exhaust valve by the electromagnet 27, after With the determined pressure values ​​and the opening cross section predetermining contour according to FIG. 2 take place, that it is in the same way both sensitive and a large-volume, rapid venting of the consumer possible.

The operation of the above described pressure control device is as follows: When braking is a given from the brake signal transmitter 9 target braking signal supplied via the connector 17 of the electronic control unit eleventh The electronic control unit closes across the electromagnet 27 and its Actuating plunger 29, the exhaust valve 35 (Fig. 1) and activated by means of the Electromagnet 23, the inlet valve 33 exceeds the magnetic force of the Electromagnet 23, the spring force of the spring 49 and on the valve piston applied frictional forces so the valve piston starts moving and opens the relative to the housing existing valve seat 51, so that the supply air of the Compressed air supply 3 through the inlet 37 and the open inlet valve in the Pressure means chamber 39 and from there to the consumer. Simultaneously, the which builds up in the fluid chamber 39 pressure continuously by the pressure sensor 31 measured the pressure constant at the built-in electronic control unit 11 passes. The electronic control unit compares the predetermined brake signal with the actual value of the brake pressure and regulates the inlet valve 33 until this again closes. The brake pressure is now constant, since the exhaust valve 35 in closed position is. If the brake pressure will be reduced, as happens this via the outlet valve 35 and the outlet 43, which analogously to Atmosphere leads. With the aid of the above-described querschnittsänderlichen Characteristic of the intake valve are both full cross sections with rapid Pressure rise as needed for emergency braking, but also small Flow cross sections and thus slow pressure changes, as in sensitive Braking required permits. Accordingly, it is a dynamic history the brake signal, for example a rapid pressure rise to approximately 90% of the recoverable Brake pressure, and then a slow increase in pressure, solely by the Change the flow cross section, can be achieved.

In FIG. 4, a pressure control device according to a further embodiment of the Invention reproduced. The pressure control device is in this case with a additional brake pressure retaining valve 53 is provided; This interacts with a single and Exhaust valve 55 together, at which the compressed air supply 3 is connected. at electrical control via the brake signal transmitter 9 and operation of the Intake valve 33, the inlet and outlet valves 55 is simultaneously opened such that represented by the forthcoming from the compressed air reservoir 3 reservoir pressure Brake pressure retaining valve 53 in the closed position on a housing-side valve seat held 57th When intake valve 33 is open, the pressure takes the Consumer, ie, the brake cylinder 5 in. With reference to FIG 1 explained manner. For the pressure reduction when the intake valve is closed, the Exhaust valve 35 is actuated by means of the electromagnet 27, ie the valve piston thereof is moved to the open position downwards (Fig. 4), such that the connection between the consumer and the pressure-relief device consists. In a shutdown or failure of the scheme by the Control unit 11 and actuating the brake signal transmitter 9 is of the pneumatic Encoder portion thereof originating in brake pressure if it opens brake pressure retaining valve 53 through controlled in the direction of the consumer, in the Ratio 1: 1. The brake pressure retaining valve 53 in this case assumes the opened Location a, since the over the inlet and outlet valves 55 from the compressed air reservoir 3 pressure prevailing in shutdown of the electro-pneumatic control loop shut off and the brake pressure retaining valve via the opened inlet and Exhaust valve 55 is vented as shown in Fig. 4. Ensuring that a brake pressure while driving may not be established, is carried out at the Embodiment of Fig. 4 by the brake pressure retaining valve and the pneumatic part of the brake signal transmitter 9 in the form of the foot brake valve, ie, Venting of the load is in the driving state of the vehicle always on the pneumatic transducer portion of the brake signal transmitter or its vent port ensured. For this reason, the intake valve 33 and exhaust valve 35 may in Unlike the embodiment of FIG. 1 are identical in design.

LIST OF REFERENCE NUMBERS

<dl tsize="3" compact="compact"><dt>1</dt><dd>Pressure control device</dd><dt>3</dt><dd>Compressed air reservoir</dd><dt>5</dt><dd>brake cylinder</dd><dt>7</dt><dd>wheel</dd><dt>9</dt><dd>electropneumatic brake signal transmitter</dd><dt>11</dt><dd>electronic control unit</dd><dt>13</dt><dd>valve means</dd><dt>15</dt><dd>control line</dd><dt>17</dt><dd>plug</dd><dt>19</dt><dd>housing</dd><dt>21</dt><dd>housing</dd><dt>23</dt><dd>electromagnet</dd><dt>25</dt><dd>actuating ram</dd><dt>27</dt><dd>electromagnet</dd><dt>29</dt><dd>actuating ram</dd><dt>31</dt><dd>pressure sensor</dd><dt>33</dt><dd>intake valve</dd><dt>35</dt><dd>Outlet valve</dd><dt>37</dt><dd>Inlet</dd><dt>39</dt><dd>Fluid chamber</dd><dt>41</dt><dd>outlet</dd><dt>43</dt><dd>outlet</dd><dt>45</dt><dd>silencer</dd><dt>47</dt><dd>plunger</dd><dt>49</dt><dd>feather</dd><dt>50</dt><dd>plunger </dd><dt>51</dt><dd>valve seat</dd><dt>53</dt><dd>Brake pressure retaining valve</dd><dt>55</dt><dd>Inlet and outlet valves</dd><dt>57</dt><dd>valve seat</dd></dl>