JP7573014B2 - Valve gear for a double acting piston compressor - Google Patents

Description

The present invention relates to a double-acting piston compressor for a compressed air supply system in a motor vehicle, such as a truck, a bus or a rail vehicle. The double-acting piston compressor essentially has two regions, namely a cylinder head region in which the valves are arranged and a crankshaft casing with at least one cylinder, which is movable in a working chamber, so that a suction stroke movement and a compression stroke movement occur. The double-acting piston compressor may be configured as a single-stage or multi-stage, in particular as a two-stage.

The valve mechanism that controls the air flow is generally located in correspondence with the cylinder head and has automatically operating intake and discharge valves that are opened and closed by the pressure prevailing in the working chamber based on the stroke motion of the piston.

The intake stroke of the piston creates a negative pressure in the working chamber of each cylinder, which opens the corresponding intake valve and closes the corresponding discharge valve. Air enters or is sucked into the working chamber of the cylinder through the inlet chamber and the inlet passage in the valve support plate.

The compression stroke of the piston creates excess pressure in the working chamber of each cylinder, which closes the corresponding intake valve and opens the corresponding discharge valve, allowing compressed air to be pumped from the working chamber of the cylinder through the pressure passage to the subsequent compressed air system.

As is also known from DE 10 2016 006 358 A1, the intake valve is usually formed as a valve lamella, the valve tongue of which is clamped on one side between the cylinder casing and the cylinder head of the double-acting piston compressor and guided at its free end with at least one tongue into a recess in the cylinder casing. The valve tongue can close an inlet opening in the valve support plate, which connects the intake chamber to the working chamber of the cylinder. Furthermore, the valve lamella is designed in such a way that at least one outlet opening is cut out in the valve support plate, which is arranged between the working chamber of the cylinder and the pressure passage. The discharge valve, which can close the outlet opening, is generally located inside the cylinder head area.

The double-acting piston compressor operates in a pumping mode until the pressure in the main pressure line reaches a preset stop pressure. The compressor is then switched to idling mode, which reduces the power consumption during idling mode. Such a system is also called a pressure relief system or idling system.

From EP 1 650 434 A1, for example, an idling valve is known which opens automatically as soon as the system pressure is reached and the relief valve opens. This eliminates any back pressure in the compressed air system which would keep the idling valve in the closed position. Since the open idling valve connects the working chamber to the inlet chamber, there is no risk of compression during the compression stroke. The advantage of such a piston compressor is that the shutoff is automatic when the target filling pressure is reached in the pressure vessel.

Another idling valve is known, for example, from DE 10 2013 001 147 A1. The idling valve proposed there for a pressure relief system can be held in the closed position by a spring and switched to the open position by selectively applying pressure. Such a system is also called an "external control system".

From EP 0 091 994 an idling valve arrangement is known, which is arranged so as not to extend into the area across the piston of the compressor.

As is common to all idle systems, during idle operation, no or very little compression takes place, since the working chamber is connected to another chamber via a pressure relief passage.

The objective of this invention is to propose a pressure relief system that significantly reduces the energy consumption of a double-acting piston compressor.

This problem is solved according to the invention by the configuration according to claim 1. Further advantageous features of the configuration according to the invention are described in the subclaims.

The configuration according to the present invention is a double-acting piston compressor for a compressed air supply system installed in an automobile, which has a cylinder head incorporating a pressure relief system, and a pressure relief passage provided on a valve support plate of the cylinder head that connects the working chamber of the double-acting piston compressor to a chamber in the cylinder head can be switched via the pressure relief system.

To improve the efficiency of the double-acting piston compressor, it is proposed that the pressure relief system has a switching device and a lamella, which is attached to the valve support plate on the working chamber side and is designed to be liftable from the valve support plate to open the pressure relief passage, and the lifting of the lamella can be performed automatically and/or controlled via the pressure relief system.

The automatic lifting of the thin plate results in an enlarged effective passage cross section, which in turn reduces the resistance to air flow into the working chamber during the intake stroke of the cylinder.

The controlled lifting of the plates allows the compressor to switch to idle operation where no compression takes place.

One preferred embodiment may envisage that the cylinder head has an inlet chamber, which can be connected to the working chamber via a number of inlet passages in the valve support plate and an inlet valve lamella formed as an automatically actuating reed valve, and at least one relief passage is arranged inside the inlet passages. In other words, the at least one relief passage is surrounded by the inlet passages.

In this case, the plate may preferably be configured as a reed valve, by which is meant a plate that is clamped on one side and closes the passage in the inoperative position and opens the flow through the passage in the operative position.

Advantageously, the inlet chamber can be connected to the working chamber via an inlet passage and a pressure relief passage. The inlet chamber is connected to an air inlet, via which, in particular, ambient air flows into the inlet chamber. In the inlet chamber, the air is diverted towards the inlet passages and at least one pressure relief passage, via which it is sucked into the working chamber. The enlarged cross section facilitates the intake stroke movement of the piston, which reduces energy consumption.

Furthermore, the pressure relief system may contain means for limiting the stroke of the lamella in order to support the lamella. In particular, in the case of large air volumes sucked in by the negative pressure occurring during the intake stroke into the working chamber, it may be necessary to limit the lamella movement, as is also necessary with valve lamellas corresponding to the prior art. To limit the stroke of the lamella, for example, a limiting lamella that projects into the working chamber may be used. In order to nevertheless keep the dead space relatively small, the cylinder may have a corresponding recess for the limiting lamella. Alternatively, this recess may be used directly as a limiting means, so that the lamella rests against the recess at least at the beginning of the stroke.

The pressure relief system may further include a pressure relief piston that can return via a spring member, and the pressure relief piston can be operated by the control pressure.

In one alternative configuration, the double-acting piston compressor can be designed as a two-stage compressor with a front stage and a high-pressure stage, in which case a pressure relief system and a connecting passage connecting the pressure relief passage of the high-pressure stage to the inlet chamber are provided in the cylinder head for each stage. In the case of a multi-stage compressor, the pressure relief during the compression stroke of all stages is carried out via a connection that controls and connects the respective working chamber to the inlet chamber via the pressure relief passage. Thus, in the pressure relief position of the lamella, ambient air can flow directly into the working chamber even during the intake stroke of the high-pressure stage.

Unlike the lamellae of the preceding stage, the lamellae of the pressure relief system of the high-pressure stage are designed to remain in the closed position during the intake stroke during operation. That is, the lamellae of the high-pressure stage or the following high-pressure stage are designed in such a way that they can only be actively moved via the piston of the pressure relief system.

Furthermore, a method for operating a double-acting piston compressor for generating compressed air for commercial vehicles is proposed. The double-acting piston compressor has a cylinder head with an integrated pressure relief system, by means of which a pressure relief passage provided in a valve support plate of the cylinder head can be switched, connecting a working chamber of the double-acting piston compressor to a chamber in the cylinder head.

The method is characterized in that during the intake stroke, when a negative pressure is generated in the working chamber, the lamella of the pressure relief system is automatically or, when the pressure relief system is activated, is forced to move to an open position, so that additional air can be sucked into the working chamber via the inlet chamber and the pressure relief passage, or air can be discharged from the working chamber via the pressure relief passage when the pressure relief system is activated. This method is used in a single-stage double-acting piston compressor or in the first or first stage of a multi-stage double-acting piston compressor.

In one configuration of a double-acting piston compressor as a two-stage compressor, the upstream and high-pressure stages are connected in series one behind the other, with a pressure relief system being provided in the cylinder head of each stage. In such a configuration, the lamella of the upstream stage may be designed to be automatically moved to an open position during the intake stroke, and the lamella of the high-pressure stage to remain in a closed position during the intake stroke.

Furthermore, a connecting passage for connecting the pressure relief systems may be provided in the cylinder head of the two-stage compressor, in which case the pressure relief passage of the high-pressure stage is connected to the inlet chamber of the previous stage via a connecting passage, in which case, in order to relieve pressure from the double-acting piston compressor or to switch to idling operation, the pressure relief pistons of both pressure systems are switched, so that the thin plates of both stages are moved to the open position.

The present invention will be explained in more detail below with reference to examples.

FIG. 2 shows the piston side of the valve plate of a two-stage double-acting piston compressor with a pressure relief system. FIG. 2 shows the cylinder head side of the valve plate of a two-stage double-acting piston compressor equipped with a pressure relief system. FIG. 4 is a cross-sectional view showing a pressure relief system of the first compressor stage. FIG. 4 is a cross-sectional view showing a pressure relief system of the second compressor stage.

1 shows the piston side of the valve support plate 4 of a two-stage double-acting piston compressor with a pressure relief system, which is arranged in correspondence with the cylinder head 12. The two compressor stages, the front stage 2 and the high-pressure stage 3, are similarly designed, but differ slightly from each other in terms of size and function. The basic structure is the same. Both compressor stages have inlet valves 5a, b, which are fixed on one side and have stop surfaces on the opposite sides. For the stop surfaces, recesses (not shown here) are provided in the crankshaft casing 11, which limit the opening movement of the inlet valves 5a, b. Inside the outer contour of the inlet valves 5a, b, a number of outlet passages 23 are arranged and extend partially through the recesses into the inlet valves 5a, b. Approximately in the center of the inlet valves 5a, b, i.e. in the center of the working chamber of the cylinder 20a, b in which the inlet valves 5a, b have recesses, are arranged the thin plates 9a, b belonging to the pressure relief system 7a, b. The thin plates 9a, b are also clamped on one side.

Due to the different functions of the pressure relief systems 7a, b, the valves of the front stage 2 and the high pressure stage 3 are also slightly different. Due to the larger air volume that must be sucked in during the intake stroke of the cylinder 20a of the front stage 2, the lamella 9a is designed to open automatically with every intake stroke of the cylinder 20a of the front stage 2. To limit the opening movement, a limiting lamella 22 is provided, which constitutes a stop for the lamella 9a.

Figure 2 shows the cylinder head side of the valve support plate 4 of a two-stage double-acting piston compressor with a pressure relief system. In this view, the passages and chambers of the compressor stages can be clearly seen. Both stages 2, 3 each have an inlet chamber 14a, b and an outlet chamber 15a, b. In the outlet chambers, automatically operating outlet valves 6a, b are arranged, which in the closed position close the outlet passage 23 in the valve support plate and are moved to the open position when a predeterminable pressure in the working chamber is exceeded.

In the region of the inlet chamber 14a of the front stage 2, several passage openings through the valve support plate 4 are shown. Some of these openings, i.e. the outer semicircular parts, are inlet passages 21a arranged corresponding to the inlet valve 5a with the inlet valve lamella 18a. When air is sucked into the working chamber through the inlet passage 21a during the intake stroke, the inlet valve lamella 18a is moved to the open position. During the compression stroke, the inlet valve lamella 18a closes the inlet passage 21a. Inside the semicircular parts of the inlet passage 21a, several pressure relief passages 19a are arranged. The flow section of the pressure relief passage 19a is switched by the lamella 9a of the pressure relief system 7a.

The high-pressure stage is designed slightly differently, in that the pressure relief passage 19b of the pressure relief system 7b is arranged in a separate chamber connected to the inlet chamber 14a of the front stage 2 via a connecting passage 13. A separate passage connection between the outlet chamber 15a of the front stage 2 and the inlet chamber 14b of the high-pressure stage 3 is not shown.

In Fig. 3 and Fig. 4 the pressure relief system 7a of the front stage 2 and the pressure relief system 7b of the high pressure stage 3 are shown in cross-section. The general layered construction of the cylinder head 12 is known from the prior art, so we will continue to look only at the passages and chambers that are important for the invention. The pressure relief system 7a according to the invention for the front stage is shown in Fig. 3, the pressure relief system 7b for the high pressure stage 3 is shown in Fig. 4.

In the case of a single-stage compressor, the pressure relief system 7a of the preceding stage may be used as described above and shown in FIG. 3. In the case of a multistage compressor, i.e. two or more stages, all subsequent stages have a pressure relief system 7b of the high-pressure stage 3, in which case in one preferred configuration, connecting passages may be provided that can connect all stages to the inlet chamber of the preceding stage. Alternatively, each stage may have a separate passage connected to the surrounding environment.

The feature of the pressure relief valve of the first stage 2 is the limiting thin plate 22, which is formed as a solid component and supports the thin plate 9a, so that the thin plate 9a does not bend excessively into the working chamber, which would cause excessive bending stress. The cylinder 20a has a recess on the end face into which the limiting thin plate 22 enters when the cylinder is at top dead center, minimizing dead space. This recess is sized so that the limiting thin plate 22 and the thin plate 9a located above the limiting thin plate 22 in the open state fit within the recess.

Furthermore, a pressure relief piston 10a can be seen, which is guided in the cylinder head 12. In the position shown, the pressure relief piston 10a is in a rest position and is held in this position by a spring. Pressure can be supplied to the pressure relief piston 10a via the illustrated control pressure passage 16, so that the pressure relief piston 10a is moved into the pressure relief position and the lamella 9a is moved into the open position.

The pressure relief system 7b of the high pressure stage 3 shown in FIG. 4 is characterized by the design of the lamella 9b, which is designed with spring stiffness so that it can only move to the open position with the assistance of the pressure relief piston 10b. The intake stroke of the piston 20b of the high pressure stage 3 does not cause the lamella 9b to move automatically to the open position. Both pressure relief pistons 10a,b are supplied with compressed air simultaneously via the control pressure passage 16 shown. The piston 20b also has a recess in which the lamella 9b is located in the open position.

REFERENCE SIGNS LIST 1 double-acting piston compressor 2 front stage 3 high pressure stage 4 valve support plate 5a, b inlet valve 6a, b outlet valve 7a, b pressure relief system 8a, b switching device 9a, b lamella 10a, b pressure relief piston 11 crankshaft casing 12 cylinder head 13 connecting passage 14a, b inlet chamber 15a, b outlet chamber 16 control pressure passage 17 cooling passage 18a, b inlet valve lamella 19a, b pressure relief passage 20a, b piston in working chamber 21a, b inlet passage 22 limiting lamella 23 outlet passage 24 inlet section ambient air

Claims (11)

A double-acting piston compressor (1) for a compressed air supply system to be installed in a motor vehicle, comprising a cylinder head (12) having a valve support plate (4) and an inlet valve lamella (18a) by means of which an inlet chamber (14a, b) can be connected to a working chamber via a plurality of inlet passages (21) provided in the valve support plate (4), and a pressure relief system (7a, b) integrated in the cylinder head (12) through which pressure relief is provided to the valve support plate (4). a pressure relief passage (19a, b) connecting the working chamber to the inlet chamber (14a, b) in the cylinder head (12) can be switched between open and closed states by a switching device (8a, b) , the pressure relief system (7a, b) has the switching device (8a, b) and a thin plate (9a, b), the thin plate (9a, b) is attached to the valve support plate (4) on the working chamber side and can be lifted from the valve support plate (4) to open the pressure relief passage (19a, b),
1. A double-acting piston compressor (1), characterized in that the lifting of the lamellae (9a, b) can take place automatically during suction and in a controlled manner via a pressure relief system. The double-acting piston compressor (1) according to claim 1, wherein the inlet valve lamella (18a, b) has a recess in which at least one pressure relief passage (19a, b) and the lamella (9a, b) are arranged. A double-acting piston compressor (1) according to claim 2, wherein the thin plates (9a, b) are configured as reed valves. The double-acting piston compressor (1) according to claim 2, wherein the pressure relief system (7a, b) includes means for limiting the stroke of the lamellae (9a, b) to support the lamellae (9a, b). The double-acting piston compressor (1) according to claim 4, wherein the means for limiting the stroke of the lamella (9a) is a limiting lamella (22) that projects into the working chamber. The double-acting piston compressor (1) according to claim 1, wherein the pressure relief system (7a, b) has a pressure relief piston (10a, b) that can return via a spring member, and the pressure relief piston (10a, b) can be operated by a control pressure. The double-acting piston compressor (1) is formed as a two-stage compressor with a front stage (2) and a high-pressure stage (3), and the cylinder head (12) is provided with a pressure relief system (7a, b) for each stage and a connecting passage (13) that connects the pressure relief passage (19b) of the high-pressure stage (3) to the inlet chamber (14a) of the front stage (2). The double-acting piston compressor (1) according to claim 1. The double-acting piston compressor (1) according to claim 7, wherein the pressure relief system (7b) of the high-pressure stage (3) has a thin plate (9b) designed to remain in a closed position during the intake stroke during operation. A method for operating a double-acting piston compressor (1) for generating compressed air for a commercial vehicle, the double-acting piston compressor (1) having a cylinder head (12) with two pressure relief systems (7a, b) assembled therein, the open/closed state of pressure relief passages (19a, b) provided in a valve support plate (4) of the cylinder head (12) connecting a working chamber of the double-acting piston compressor (1) to an inlet chamber (14a, b) in the cylinder head (12) can be switched by a switching device (8a, b) via the pressure relief systems (7a, b),
13. A method according to claim 12, wherein during the intake stroke, when a negative pressure is created in the working chamber, a lamella (9a) of the pressure relief system (7a) is automatically and, when the pressure relief system (7a) is activated, is forced to move to an open position, so that additional air is sucked into the working chamber (20a) via the inlet chamber (14a) and the pressure relief passage (19a) , and during the compression stroke, air can be discharged from the working chamber (20a) via the pressure relief passage (19a). The method according to claim 9, wherein the double-acting piston compressor (1) is formed as a two-stage compressor with a front stage (2) and a high-pressure stage (3), a pressure relief system (7a, b) is provided for each stage (2, 3) in the cylinder head (12), and the lamella (9a) of the front stage (2) is automatically moved to an open position during the intake stroke, and the lamella (9b) of the high-pressure stage (3) is designed to remain in a closed position during the intake stroke. 11. The method according to claim 10, further comprising the steps of: providing a connecting passage (13) in the cylinder head (12) of the two-stage compressor (1) for connecting the pressure relief systems (7a, b), the pressure relief passage (19b) of the high-pressure stage (3) being connected to the inlet chamber (14a) of the previous stage (2) via the connecting passage (13); and, in order to relieve the double-acting piston compressor (1), the pressure relief pistons (10a, b) of both pressure relief systems (7a, b ) are switched, whereby the lamellae (9a, b) of both stages (2, 3) are moved into their open position.

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