Valve assembly and charging system for an internal combustion engine with such a valve assembly

Abstract

Valve assembly (12) with at least one spring element (22) and a shut-off body (14) which is movable from a closed position to at least one open position against a spring force applied by the spring element (22), characterized in that the valve assembly (12) has a pressurizable working chamber (34) in which a piston (36) connected to the shut-off body (14) is movably received, by which the working chamber (34) is divided into two working chambers (40, 42) which are fluidically connected via at least one connecting channel (50) opening into each of the working chambers (40, 42), wherein one of the openings (52, 54) can be at least substantially fluidically closed when moved into the open position by the piston (36), wherein the working chamber (34) is formed by a valve body (16) on which the spring element (22) is supported on one side.

Description

[0001] The invention relates to a valve device according to the preamble of claim 1 and a charging device with such a valve device according to claim 5.

[0002] DE 10 2006 020 354 A1 discloses a check valve with a valve seat and a valve disc, which is held on the valve seat against the intended flow direction by means of a closing spring with a predetermined characteristic curve. A characteristic curve is superimposed on the closing spring's characteristic curve by means acting on the valve stem, so that the resulting characteristic curve exhibits a linear increase until the valve opens, subsequently transitioning into a negative characteristic with subsequent saturation. A valve is also known from WO 2008 / 122 311 A1.

[0003] Furthermore, valves are known from the mass production of internal combustion engines. These valves comprise a shut-off element and function based on the existence of different pressures in the fluid being conveyed on two opposite sides of the shut-off element. When a predetermined pressure difference is applied, the shut-off element moves, opening a flow cross-section for the fluid. To close the valve, a force is applied to the shut-off element. This force causes the shut-off element to move and open the flow cross-section only when a predetermined pressure difference is exceeded. However, this force also causes a pressure drop when the fluid flows around the shut-off element in the open state. Only then do the different pressures on the opposite sides occur, generating a force that holds the valve open against this pressure.However, this pressure loss is disadvantageous.

[0004] It is therefore an object of the present invention to provide a valve device and a charging device with such a valve device in which this pressure loss of the fluid is at least reduced.

[0005] This problem is solved by a valve device with the features of claim 1 and by a charging device with the features of claim 5. Advantageous embodiments with expedient and non-trivial further developments of the invention are specified in the dependent claims.

[0006] Such a valve assembly with at least one spring element and a shut-off body, which is movable from a closed position to at least one open position against a force applied by the spring element, is characterized according to the invention in that the valve assembly has a pressurizable working chamber in which a piston connected to the shut-off body is movably received, by which the working chamber is divided into two working chambers. The working chambers are, for example, arranged opposite each other. The working chambers are fluidically connected via at least one connecting channel opening into each working chamber via at least one opening, wherein one of the openings of the connecting channel can be at least substantially fluidically blocked by the piston when it moves into the open position.

[0007] In other words, as the piston moves into the open position, it closes one opening of the connecting channel once it reaches a certain position in the working chamber, thus separating the two working chambers from each other fluidically. One of the working chambers is therefore at least substantially sealed. This chamber is pressurized, acting on the piston and, via the piston, on the shut-off element, thereby assisting the movement of the shut-off element into the open position against the applied force. Advantageously, the other working chamber is pressurized, or a corresponding pressure is applied, which is lower than the pressure in the fluidically sealed working chamber.

[0008] In contrast, the fluidic connection between the two working chambers, when the piston is in a corresponding position within the working chamber, ensures that no additional force acts on the piston or, via the piston, on the shut-off element, opposing the applied force. This creates a self-regulating valve device, in particular a self-regulating check valve, in which the pressure losses of a fluid flowing around the shut-off element, as described above, are at least reduced.

[0009] The working chamber can be pressurized via a channel or similar conduit fluidically connected to the working chamber. This channel or conduit fluidically communicates with the first working chamber and, when the piston is in a corresponding position within the working chamber, also with the second working chamber via the connecting channel. The second working chamber is at least substantially sealed when the piston is in a corresponding position within the working chamber. If the piston moves within the working chamber and blocks the corresponding opening of the connecting channel, the channel is fluidically connected only to one of the working chambers—namely, the working chamber that is not at least substantially sealed. Advantageously, a pressure is then established via the channel in the working chamber fluidly connected to the channel, which is lower than the pressure in the sealed working chamber.

[0010] When the valve device according to the invention is used in or with an internal combustion engine, the channel can, for example, be fluidically connected to a suitable location of the internal combustion engine, such as a location of an air supply device for supplying the internal combustion engine with air, so that a suitable pressure can be drawn from this location and applied to the corresponding working chamber. Thus, from the moment the orifice is blocked by the piston, a force can be exerted on the piston, which assists in moving the shut-off element into the open position against the force exerted on the shut-off element by the fluid flowing around it.

[0011] The point where the channel is fluidically connected is advantageously a point where a pressure drop occurs or where a correspondingly lower pressure prevails than in the sealed working chamber, even if moving the shut-off element into the open position is desirable and advantageous.

[0012] In the invention, the working space is formed by a valve body on which the spring element is supported on one side.

[0013] The invention also includes a charging device for an internal combustion engine with at least two exhaust gas turbochargers connected in series, wherein, in the direction of exhaust gas flow through a respective turbine, the first exhaust gas turbocharger is designed as a high-pressure exhaust gas turbocharger and the second exhaust gas turbocharger as a low-pressure exhaust gas turbocharger, and with at least one valve arrangement according to the invention. In such a two-stage and, in particular, controlled exhaust gas turbocharging of the internal combustion engine by the charging device, it is advantageous to bypass a compressor of the high-pressure exhaust gas turbocharger in certain operating conditions of the internal combustion engine by means of a bypass device, which is referred to as bypassing, so that the compressor of the high-pressure exhaust gas turbocharger does not further compress the air supplied to the internal combustion engine that has already been pre-compressed by a compressor of the low-pressure exhaust gas turbocharger.This is advantageous because the compressor of the high-pressure exhaust gas turbocharger is usually small in terms of its dimensions and would otherwise adversely limit the airflow of the internal combustion engine.

[0014] This bypassing is advantageously always performed at a substantially constant airflow rate and at least substantially independent of the boost pressure or load currently applied to the internal combustion engine. Therefore, it is advantageous to use as the control variable or control pressure for the open working chamber of the combustion chamber, which is to be pressurized via the channel, a pressure that prevails in the direction of airflow through the compressor of the high-pressure exhaust gas turbocharger and through the compressor of the low-pressure exhaust gas turbocharger upstream of the compressor of the low-pressure exhaust gas turbocharger, or in the direction of exhaust gas flow through the respective turbine of the exhaust gas turbochargers downstream of the turbine of the low-pressure exhaust gas turbocharger. The channel is then to be fluidically connected to the corresponding points.

[0015] Further features, advantages, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, are not limited to the combinations specified or can be used individually without departing from the scope of the invention.

[0016] The drawing shows in: Fig. 1 a schematic sectional view of a valve device with a piston movably arranged in a receiving space, which assists in moving a shut-off element of the valve device from a closed position to at least one open position, wherein the shut-off element is in the closed position; Fig. 2 a schematic longitudinal sectional view of the valve assembly according to Fig. 1, wherein the shut-off body is in an open position; Fig. 3 a schematic longitudinal sectional view of the valve assembly according to the preceding figures, wherein the shut-off element is in a further open position; and Fig. 4 A schematic longitudinal sectional view of the valve assembly according to the preceding figures, wherein the shut-off element is in a further open position.

[0017] The Fig. Figures 1 to 4 show a line 10, which is designed, for example, as a bypass line for a bypass device of a charging system of an internal combustion engine. The charging system comprises, for example, two exhaust gas turbochargers connected in series, each having a turbine through which exhaust gas from the internal combustion engine flows and a compressor through which air drawn in by the internal combustion engine flows. The exhaust gas turbocharger with the turbine through which the exhaust gas flows first is called a high-pressure exhaust gas turbocharger, since the exhaust gas has a very high pressure and is expanded by the turbine to a comparatively lower pressure level. The exhaust gas turbocharger with the turbine through which the exhaust gas flows second is called a high-pressure exhaust gas turbocharger.The turbine through which the exhaust gas flows is called a low-pressure exhaust gas turbocharger, since the exhaust gas flows into the turbine of the low-pressure exhaust gas turbocharger at a lower pressure than into the upstream turbine of the high-pressure exhaust gas turbocharger.

[0018] In such a two-stage turbocharging system of the internal combustion engine with two exhaust gas turbochargers, it is advantageous at certain operating points of the engine to bypass the compressor of the high-pressure exhaust gas turbocharger using the bypass device. The compressor of the high-pressure exhaust gas turbocharger is arranged downstream of the compressor of the low-pressure exhaust gas turbocharger in the direction of airflow. This bypass of the compressor of the high-pressure exhaust gas turbocharger via line 10 is advantageous, for example, because the compressor, and in particular one compressor wheel of the compressor of the high-pressure exhaust gas turbocharger, is small in its dimensions and smaller than the compressor of the low-pressure exhaust gas turbocharger, and would otherwise undesirably limit the airflow of the internal combustion engine at the corresponding operating points.At other operating points, such bypassing is undesirable and disadvantageous.

[0019] To effect or cancel this bypass, a valve assembly 12 is provided, which comprises a shut-off element 14 and a valve body 16 that is at least substantially cylindrical. The shut-off element 14 is located between a Fig. 1 shown closed position and several open positions, of which in the Fig. Figures 2 to 4 are shown, and the valve is movable. In the closed position, the shut-off element 14 sits on a corresponding valve seat 18 and fluidically blocks the line 10, so that the air cannot flow through the line 10 in the direction of arrow 20 and bypass the compressor of the low-pressure exhaust gas turbocharger. In the open positions, the shut-off element 14 is lifted from the valve seat 18, and the air can flow through the line 10 in the direction of arrow 20 and bypass the compressor of the low-pressure exhaust gas turbocharger.

[0020] How the Fig. As can be seen from Figures 1 to 4, the valve assembly 12 further comprises a spring element 22, which is supported at one end on the valve body 16 and at the other end on the shut-off element 14. By means of the spring element 22, the shut-off element 14 is subjected to spring force and is pressed onto its valve seat 18 in the direction indicated by a directional arrow 24.

[0021] A pressure p prevailing in the line 10 acts from one side 26 of the shut-off body 14. ND on the shut-off body 14, resulting in a force that pushes the shut-off body 14 in the direction indicated by a directional arrow 28. Likewise, a pressure p prevailing in the line 10 acts on the shut-off body 14 from one side 30 of the shut-off body 14 opposite side 26. HD , from which a force results that acts on the barrier body 14 in the direction according to a direction arrow 32.

[0022] A receiving chamber 34 is formed by the valve body 16, which is fixed relative to the line 10. A piston 36 of the valve assembly 12 is received in this receiving chamber 34. The piston 36 is translationally movable relative to the valve body 16 in the receiving chamber 14 in the direction indicated by an arrow 38, thus dividing the receiving chamber 34 into a first working chamber 40 and a second working chamber 42. Furthermore, the piston 36 is connected to the shut-off element 14 via a piston rod 44, so that the piston 36 and the shut-off element 14 can move together. The piston 36 applies an additional force to the shut-off element 14, beyond the spring force, thereby allowing the shut-off element to open further against the spring force. This additional force can arise because, depending on the pressure conditions in the working chambers 40 and 42, different pressures can act on the piston or on the corresponding working surfaces 46 and 48 of the piston.

[0023] In one of the Fig. In the initial state of the valve assembly shown in Figure 1, the valve assembly 12 is closed and the shut-off element 14 is seated on its valve seat 18. The working chambers 40 and 42 are fluidically connected to each other by means of a connecting channel 50, the connecting channel 50 opening into the working chamber 40 via a first opening 52 and into the second working chamber 42 via a second opening 54. Furthermore, the working space 34 is supplied with a control pressure p via a channel 56. SteuerThe channel 56 can be acted upon according to a directional arrow 58, wherein the channel 56 communicates fluidically, for example, with a point which is arranged upstream of the compressor of the low-pressure exhaust gas turbocharger in the direction of air flow or downstream of the turbine of the low-pressure exhaust gas turbocharger in the direction of exhaust gas flow. In other words, the same pressure prevails in the channel 56 as upstream of the compressor of the low-pressure exhaust gas turbocharger or as downstream of the turbine of the low-pressure exhaust gas turbocharger.

[0024] Again Fig. As can be seen from Figure 1, the piston 36 releases both openings 52 and 54, so that the control pressure p Steuer in the channel 56, in the working chamber 40, in the connecting channel 50, and in the working chamber 42, and thus on both sides of the piston 36. In this, in the Fig. In the initial position of the valve assembly 12 shown in Figure 1, no additional force is exerted by the piston 36 via the piston rod 44 on the shut-off element 14. The piston is free of force. This is the case, for example, under partial load of the internal combustion engine.

[0025] However, if the pressure p increases ND On side 26 of the shut-off body 14, the force acting on the shut-off body 14 from side 26 also increases, and the shut-off body 14, and thus the piston 36, move relative to the valve body 16, which is fixed relative to the line 10, in the direction of the opening 52 of the connecting channel 50. The valve assembly 12 begins to open, as can be seen from the Fig. 2 is shown.

[0026] In the Fig. In the open position shown in Figure 2, however, the piston 36 still exposes both openings 52 and 54, so that the piston 36 is still force-free and no additional force acts on the shut-off element 14. If the valve assembly 12 opens further in a self-regulating manner, as shown in Figure 2, the piston 36 is still free of force and no additional force acts on the shut-off element 14. Fig. 3 and Fig. As shown in Figure 4, the piston 36 eventually passes over the opening 52 and closes it fluidically, so that the working chamber 42 no longer communicates fluidically with the working chamber 40 and the working chamber 42 is at least substantially sealed fluidically. The pressure in the working chamber 42 then remains at least substantially constant. A sufficiently large compensation volume must be provided for the now sealed working chamber 42 so that, with further movement of the piston 36 away from the opening 54 and the resulting increase in the volume of the working chamber 42, the pressure prevailing in the working chamber 42 actually remains at least substantially constant and does not drop undesirably sharply as a result of the volume increase.

[0027] Since the channel 56 and thus the working chamber 40 are fluidically connected to a suitable point on the internal combustion engine, a suitable pressure prevails in the channel 56 and in the working chamber 40, and thus on the side of the effective surface 46 of the piston 36 (which is lower than the pressure prevailing in the working chamber 42), causing a suitable force to act on the piston 36 and thus on the shut-off element 14 from the moment the orifice 52 is fluidically blocked. This force assists the opening of the valve assembly 12 beyond the extent caused by flow forces on the shut-off element 14. Fig. Figure 3 shows the sealed working chamber 42. Each further reduction of the control pressure p Steuer This results in a further force effect that supports the movement of the barrier body 14 into the open position.

[0028] The Fig. Figure 4 shows the shut-off element 14 in its maximum open position. The pressure difference between the working chamber 40 and the working chamber 42, i.e., on both sides of the piston 36, is at its maximum.

[0029] The valve assembly 12 allows the shut-off element 14 to be lifted further from its valve seat 18, thus enabling a larger flow cross-section to be opened than if the shut-off element 14 were only subjected to the flow forces resulting from the air flowing around it. The pressure losses occurring in conventional check valves are at least reduced by the valve assembly 12, which, in the closed state, functions like a conventional check valve that receives no supporting force from the piston 36.

[0030] When a certain air flow rate of the internal combustion engine is reached, the valve assembly 12 opens automatically, as the shut-off element 14 opens due to the pressures p acting on sides 26 and 30. ND or p HD The piston 36 lifts itself independently from its valve seat 18. Initially, the piston 36 is still without force. Only after a particularly short distance traveled within the valve body 16 does the piston 36 sweep over and close the opening 52. From this point on, the pressure on the side of the effective surface 48 remains at least essentially constant. If the air flow rate of the internal combustion engine increases further, the control pressure p drops. Steuer (Pressure on the side of the effective surface 36) successively until the point in the Fig. The maximum opening shown in Figure 4 is further reduced. This is particularly the case when the control pressure p is used. SteuerThe pressure upstream of the compressor of the low-pressure exhaust gas turbocharger is used. This results in an increasing force that assists the opening of the valve assembly 12 or the movement of the shut-off element 14 into the open position.

[0031] If the airflow through the internal combustion engine decreases again, this support effect also diminishes until the shut-off element 14 either remains open or closes without any additional force assistance, solely due to the flow forces resulting from the airflow (depending on the prevailing pressures p). HD and P ND ).

Claims

[1] Valve assembly (12) comprising at least one spring element (22) and a shut-off element (14) which is movable from a closed position to at least one open position against a spring force applied by the spring element (22), characterized by , that the valve assembly (12) has a pressurizable working chamber (34) in which a piston (36) connected to the shut-off body (14) is movably received, by which the working chamber (34) is divided into two working chambers (40, 42) which are fluidically connected via at least one connecting channel (50) opening into the working chambers (40, 42), wherein one of the openings (52, 54) can be at least substantially fluidically closed when moved into the open position by the piston (36), wherein the working chamber (34) is formed by a valve body (16) on which the spring element (22) is supported on one side. [2] Valve assembly (12) according to claim 1, characterized by, that a movement into the open position can be supported by means of the piston (36). [3] Valve assembly (12) according to one of claims 1 or 2, characterized by , that the rear of the openings (52, 54) of the connecting channel (50) in the direction of movement from the closed position to the open position can be blocked by means of the piston (36). [4] Valve assembly (12) according to any one of the preceding claims, characterized by , that a compensation volume is provided by means of which a pressure in the working chamber (40, 42) which is closed when the mouth (52, 54) is blocked, is to be kept at least essentially constant when the piston (36) moves into the open position. [5] Charging device for an internal combustion engine with at least two exhaust gas turbochargers connected in series and with at least one valve assembly (12) according to one of the preceding claims.

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