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

The invention relates to a compressed-air reservoir of a spoked pressure control device according to the preamble of claim 1. Such a pressure control device is known from <patcit id="pcit0001" dnum="EP0644092A"><text>EP0644092A</text></patcit> known.

different kinds are used for brake pressure control actuators in electro-pneumatic brake systems. The actuators in these systems must take both the service brake and the ABS function. The aim is to allow for the service brake function both slow, sensitive pressure changes and in emergency braking or when ABS function rapid pressure changes. are used valves that can either serve both functions, or different valves separately for each function. There are, inter alia for use proportional solenoid valves with and without relay valve, with and without ABS pressure control valves, henceforth double solenoid valves for pilot control of a relay valve, with and without ABS pressure control valves, as well as current-controlled pilot solenoid valves with poppet valves, the latter for both functions.

While attempting to allow precision adjustments of the actuator pressure, pressure regulating devices have been developed are those in which provided in consumer-side monitoring of consumer pressure by a pressure sensor intake and exhaust valves, which cooperate with pilot valves, such that in the course of the electrical drive of the inlet and exhaust valves actuated electromagnets is limited enables a throttled opening of the pilot valves. With increasing excitation of the solenoids, the pilot valves are closed and the actual main valves open large cross sleekly. The desired sensitive supply of consumer pressure is determined in such control equipment through a variety of parameters; there are also intermediate or floating positions of the main valves given, which must be defined as a function of the excitation current. The structural complexity of such pressure control devices is therefore considerable, also function accuracy is required at different temperature and pressure conditions.

A disadvantage of the pressure control device the <patcit id="pcit0002" dnum="EP0644092A"><text>EP0644092A</text></patcit> is the complexity to be considered.

Assuming the object of the invention to provide simple means to design a pressure control device of the generic type so that it can fulfill both service brake and ABS functions and is particularly suited to provide both sensitive pressure changes in service braking as to allow rapid pressure changes when emergency braking or ABS functions so require. Also to be dispensed by the design of such pressure control devices, the use of pilot units.

To achieve this object the features used by the characterizing part of patent claim 1 in conjunction with the features of the preamble of patent claim 1.

By the sensor-dependent activation of the electromagnets of the inlet and outlet valve and a result of the precisely defined contour of the valve piston of inlet and outlet valve at its upstream end, it is stroke-dependent possible to reach any targeted pressure and change in volume for the consumer, which means that stroke-dependent by the change in the available cross-section between the inlet end of the valve piston and inner cross section of the valve piston directly receiving housing, the possibilities of a customized to the respective braking situation pressure course are given. The air flow is thus purposefully metered by a variable over the piston stroke of the intake and / or exhaust flow cross section. This makes it possible that:<ul><li>is made possible in emergency braking the full cross section and thus a rapid increase in pressure;</li><li>can also be carried out at an ABS control with large cross-sections;</li><li>in connection with delicate braking and slow changes small flow cross sections and thus slow pressure changes are made possible;</li><li>the dynamic variation of the brake signal, for example, increase in pressure can be implemented rapidly to about 90% of the brake pressure and then slowly increase pressure, simply by changing the flow cross-section; and that</li><li>the so-called wheel module of the brake pressure gradient for ventilation learned since the downstream volumes of brake hose and brake cylinder after installation remain constant, so that an optimal rules is provided according to the height and especially the time dependence of the brake signal.</li></ul>

Regarding the structural criteria of such pressure control device, substantial advantages are also achieved, ie both the service brake function and the ABS function can be realized with a module that henceforth there air consumption as in current braking systems, ie no increased air consumption clocking valves. It must be accepted, they are silent, as they adversely occur with stroke valves or pulsating valves. It is also of advantage that the device through its current control operates substantially independent of temperature.

Advantageous refinements and developments are specified in further claims.

The invention is explained by means of embodiments with reference to the accompanying drawings.<ul><li><figref idrefs="f0001">Fig. 1</figref> is a schematic view of the pressure control device according to the invention;</li><li><figref idrefs="f0002">FIG. 2</figref> 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><figref idrefs="f0003">Fig. 3</figref> are by means of the contours of the A, B and C <figref idrefs="f0002">figure 2</figref> recoverable flow cross sections Q1-Q3 compared to the stroke S again, being presented with Sr, the control range of available stroke; and</li><li><figref idrefs="f0004">Fig. 4</figref> is one of the <figref idrefs="f0001">Fig. 1</figref> similar schematic view of a pressure control device according to a further embodiment of the invention using a pneumatically-redundant system.</li></ul>

In <figref idrefs="f0001">Fig. 1</figref> The drawing shows a first embodiment of an electro-pneumatic brake system using the pressure control device according to the invention. 1 The pressure control device 1 is located in the illustrated example in switching to a compressed air reservoir 3, a brake cylinder 5 a schematically 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 is composed of two functional units, a schematically represented electronic control unit 11 and valve means 13, which is controlled in the following manner explained by means of the electronic control unit to 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 to control the outside air, in the illustrated embodiment.

The electro-pneumatic braking value transmitter 9 is connected to the electronic control unit 11 with its electrical part via a control line 15 and a connector 17th The electronic control unit 11 is located within a housing 19 which is connected to the underneath in the drawing, housing 21 of the valve means 13; in the housing 19 of the electronic control unit contains an electromagnet 23 with a formed by its armature actuating plunger 25, a further solenoid 27 having an actuating plunger 29 and a 31 to the electronic control unit 11 attached pressure sensor, the two electromagnets 23 and 27 are likewise connected to the electronic the operation of the brake signal transmitter 9 and the pressure sensor implemented, incoming in the electronic control unit 11 variables are controlled control unit 11 connected and subject. In the housing 19 located beneath the housing 21, the valve device 13 is provided with an inlet valve 33 and an exhaust valve 35th The inlet valve monitors the connection between an inlet 37 and a fluid chamber 39, which to the consumer, that is, connected to the brake cylinder 5 via an outlet 41st The outlet valve 35 monitors the connection between the load 5 and a further outlet 43, which is connected to the atmosphere, that forms the actual relief device. In the illustrated embodiment the outlet 43 is by means of a silencer 45 with the outside air. In the illustration of<figref idrefs="f0001">Fig. 1</figref> are the two valves shown in its initial position, that is, the inlet valve 33 closes the connection between the compressed air supply 3 and the load, while the outlet valve releases the connection in the direction of ventilation, that is, the brakes of the vehicle are deflated. 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 is 49 actuated against the force of a spring and conventionally comprises means for pressure relief, ie, in the illustrated embodiment holes which extend through the valve piston, such that at both end surfaces of the valve piston pressure relief consists.

In the invention, the valve piston 47 that is provided in its direct intake area, at its the reservoir pressure end facing with a special contour design, which makes it possible to meter the airflow targeted by a variable above the piston flow cross section. The special shape at the inlet end of the valve piston 47 is a contour at the inlet cross section of the valve housing adapted so that between the valve-housing inner periphery and the outer periphery of the valve piston 47, the aforementioned specific air dosage is provided in accordance with the stroke. In<figref idrefs="f0002">FIG. 2</figref> of the drawing are shown in association with the specifically designed contour of the valve housing various contours at the inlet end of the valve piston 47th <figref idrefs="f0003">Fig. 3</figref> the drawing illustrates in accordance with the in <figref idrefs="f0002">FIG. 2</figref> Contourings shown allowed flow cross-sections in dependence on the stroke of the displaceable by the actuating plunger 25 the valve piston. The flow cross-sections Q1, Q2 and Q3 by<figref idrefs="f0003">Fig. 3</figref> are the contours A, B and C according to <figref idrefs="f0002">FIG. 2</figref> assigned. It can be seen that the contour of A leads to a linearly extending change the flow cross section, while the function of the stroke contour B induces a complete opening of the cross section after preliminary linear cross-sectional enlargement. In the contour C is the profile between the valve piston 47 and the valve housing are of different types, that is, the arc-shaped path at the inlet end of the valve stem in the corresponding<figref idrefs="f0003">Fig. 3</figref> 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 equally valid for contouring and deriving therefrom changes in cross section at the valve piston 50 of the exhaust 35th Also, the actuation of the exhaust valve by the electromagnet 27 may in accordance with in accordance with the detected pressure values ​​and the opening cross section contour predetermining <figref idrefs="f0002">FIG. 2</figref> take place, that is, it is possible in the same way both sensitive as well as a large-volume, rapid venting of the consumer.

The operation of the above described pressure control device is as follows:<ul><li>During a braking operation by a predetermined brake signal transmitter 9 target braking signal via the connector 17 of the electronic control unit 11 is supplied. The electronic control unit closes across the electromagnet 27 and the actuation plunger 29, the exhaust valve 35 (<figref idrefs="f0001">Fig. 1</figref>) 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 applied to the valve piston friction forces so the valve piston is set in motion and opens the existing relative to the housing valve seat 51, so that the supply air of the compressed air supply 3 enters through the inlet 37 and the open intake valve into the pressure medium chamber 39 and from there to the consumer. At the same time building up in the pressure medium chamber 39 pressure is continuously measured by the pressure sensor 31, which passes this pressure value to the built-in electronic control unit 11th The electronic control unit compares the predetermined brake signal with the actual value of the brake pressure, and regulates the intake valve 33 until the latter closes again. The brake pressure is now constant, since the exhaust valve 35 is in the closed position. If the brake pressure to be reduced, this is done in an analogous manner via the outlet valve 35 and the outlet 43 which leads to atmosphere. Using the above-mentioned characteristic of the intake valve querschnittsänderlichen both full cross sections with quick pressure rise, as required for emergency braking, but also small flow cross sections and thus slow pressure changes, as in sensitive braking necessary permits. Accordingly, it is a dynamic variation of the brake signal, such as a rapid increase in pressure to about 90% of the achievable braking pressure, and then a slow increase in pressure, simply by changing the flow cross section, recoverable.</li></ul>

In <figref idrefs="f0004">Fig. 4</figref> is reproduced according to a further embodiment of the invention, a pressure control device. The pressure control device is in this case provided with an additional brake pressure retaining valve 53; This cooperates with an inlet and outlet valves 55, to which the compressed air supply 3 is connected. In case of electrical actuation via the brake signal transmitter 9 and actuation of the intake valve 33 at the same time the inlet and exhaust valve 55 is opened such that the brake pressure retaining valve 53 is held in the closed position on the housing-side valve seat 57, with the forthcoming from the compressed air reservoir 3 reservoir pressure. When intake valve 33 is open, the pressurization of the consumer is given in on that of the brake cylinder 5 with reference<figref idrefs="f0001">Fig. 1</figref> explained manner. For the pressure reduction in intake valve is closed, the exhaust valve 35 is actuated by means of the electromagnet 27, ie the valve piston thereof is directed in the open position downwards (<figref idrefs="f0004">Fig. 4</figref>) Shifted in such a way that the connection between the consumer and the discharge device consists. In a shutdown or failure of the control by the control unit 11 and actuating the brake signal transmitter 9 of the same from the pneumatic transmitter part derived brake pressure is controlled at if it opens brake pressure retaining valve 53 in the direction of the consumer, in the ratio 1: 1. The brake pressure retaining valve 53 in this case assumes the opened position a, since the shut off on the inlet and outlet valves 55 from the compressed air supply 3 prevailing pressure at shutdown of the electro-pneumatic control circuit and the brake pressure retaining valve via the open inlet and outlet valves 55, as shown in<figref idrefs="f0004">Fig. 4</figref> is vented. Ensuring that a brake pressure while driving may not be established, is carried out in the embodiment of<figref idrefs="f0004">Fig. 4</figref> ensured via the brake pressure retaining valve and the pneumatic part of the brake signal transmitter 9 in the form of the foot brake valve, ie, the venting of the consumer is in the driving state of the vehicle always on the pneumatic transmitter part of the brake signal transmitter or its vent port. For this reason, the inlet valve 33 and outlet valve 35 may by in contrast to the embodiment<figref idrefs="f0001">Fig. 1</figref> be configured identically.

LIST OF REFERENCE NUMBERS

<dl id="dl0001" 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>