JP5881981B2 - Passive volume control valve - Google Patents

Description

  The present invention relates to a passive volume limiting valve for a large diesel engine. The invention further relates to a large diesel engine having such a passive amount limiting valve.

  Large diesel engines can be configured as 2-stroke engines or 4-stroke engines and are frequently used as drive units for ships, or fixed operation, for example to drive large generators for generating electrical energy Even used.

  A common rail system is established in this respect for fuel supply in current large diesel engines. In this respect, the fuel is transported by a high-pressure pump into a pressure storage unit also called an accumulator or a rail. The fuel injection nozzles of all cylinders that inject fuel into the respective cylinders are then supplied with pressurized fuel from the pressure reservoir.

  In this regard, it is known to provide each passive type amount limiting valve between the pressure storage unit and each fuel injection nozzle. This passive volume limiting valve automatically establishes communication between the pressure reservoir and each fuel injection nozzle as soon as a pre-settable amount of fuel flows from the pressure reservoir to the fuel injection nozzle in each work cycle. Has a close purpose. This can prevent the fuel from leaving in an uncontrolled or undesired manner in the event of a leak or other type of damage. Furthermore, for example for maintenance work, when the engine is turned off and the fuel is circulated at a relatively low pressure (eg 2 to 20 bar), ie to avoid clogging of the fuel system, the storage tank and pressure reservoir are When circulated through, it is possible to remove the connection line between the pressure reservoir and the fuel injection nozzle.

DE 10 2005 012165 A1

  Due to the very high fuel pressure of 1600 to 2000 bar, the passive volume limiting valve needs to have a very good and reliable sealing function.

  The problem with known passive volume limiting valves in large diesel engines arises in particular from temperature-induced fuel viscosity fluctuations. Heavy oil is usually used as fuel for large diesel engines and is typically heated to temperatures above 100 degrees due to its very high viscosity in order to be fully flowable or injectable There is a need. Furthermore, however, marine diesel oil with a sufficiently low viscosity is also used, whereby the engine is normally started and turned off. Typically, the engine is operated with marine diesel oil, particularly during the movement of the ship in the port area, and the transition is then made continuously to the operation of open sea fuel oil. However, operation with marine diesel oil typically occurs at a lower temperature in the fuel delivery system than operation with heavy oil. In addition, the viscosity of the fuel varies due to these temperature variations. However, these changes in viscosity affect the amount of fuel passing after the amount limiting valve is closed. For example, if the volume limiting valve is set to a specific amount relative to the first viscosity, the volume limiting valve will only be after a smaller amount of fuel or after a larger amount of fuel at other viscosities. May already close.

  The present invention is to provide a countermeasure against this undesirable effect. Accordingly, it is an object of the present invention to propose a passive volume limiting valve for large diesel engines in which the amount of passage after the valve automatically closes does not substantially depend on the viscosity of the medium.

  The subject matter of the present invention that satisfies these objectives is characterized by the features of the independent claims.

In accordance with the present invention, a passive volume limiting valve for a large diesel engine comprising:
A valve housing having an inlet and an outlet for the fluid medium and having a valve chamber disposed between the inlet and the outlet;
Valve bodies each having a closing element between the inlet side and the outlet side are arranged in the valve chamber, and the closing elements are configured to perform sealing in cooperation with the valve seats on the inlet side and the outlet side, respectively. And
The closing element on the inlet side is biased toward the valve seat on the inlet side by a spring,
A passive quantity limiting valve is proposed which has a piston provided in the valve body, and the outside of the piston is slidably guided through the wall of the valve chamber. At least one passage hole through which a fluid medium can flow is provided in the end face of the piston.

  The valve chamber is divided by a piston into a front chamber and a rear chamber, and at least one passage hole in the end face of the piston defines communication between the front chamber and the rear chamber. Since the passage hole is provided in the end face of the piston, it can be configured very short and therefore its flow resistance is substantially independent of the viscosity of the medium. Thereby, the passing amount after the amount limiting valve is automatically closed becomes independent of the viscosity of the medium.

  Independence from the viscosity is particularly ensured when the ratio of the length of the passage hole to the diameter of the passage hole is 4 or less for each passage hole.

  A particularly good sealing function is achieved by using a quantity limiting valve according to the invention when the closing element on the inlet side is configured to be in line contact with the valve seat on the inlet side.

  For the same reason, preferably the outlet-side closure element is configured to be in line contact with the outlet-side valve seat.

  Line contact can be easily realized, in particular, by the closure element on the inlet side or outlet side having a spherical surface that cooperates with the valve seat on the inlet side or outlet side.

  In this configuration, a preferred measure is that the center of curvature of the spherical surface is eccentric with respect to the longitudinal axis of the valve body. A smaller curvature of the sphere can be achieved in this way, thereby increasing the length of the line contact. The opening pressure, more precisely the pressure difference required to open, can be set to a smaller value.

  In a preferred embodiment, the valve seat on the inlet side or outlet side has a conical surface. A particularly good sealing action can thereby be achieved.

  If the closing elements on the inlet side and the outlet side are of the same design, it is preferable for the automatic centering of the two closing elements or of the valve body.

  According to a preferred embodiment, the valve body extends inside the spring. This is a particularly simple design structure.

  In an actual situation, it is effective that each passage hole is arranged outside the spring in the radial direction.

  It has proven to be effective in practice when the pressure difference for opening the communication between the valve seat on the inlet side and the closing element on the inlet side is between 2 and 20 bar. This is because the volume limiting valve should remain closed when fuel is circulated between the storage vessel and the pressure reservoir in a circulating operation. The pressure in the pressure storage is usually 2 to 20 bar, for example 10 bar, in a circulating operation. At this time, the pressure difference for opening the communication between the valve seat on the inlet side and the closing element on the inlet side is somewhat higher, for example set to 15 bar, so that no opening action occurs in the circulation operation. .

  In production, the piston is preferably configured as a separate part and connected to the valve body.

  More effectively, the spring is supported on the end face of the piston.

  A large diesel engine with a quantity limiting valve according to the invention is further proposed by the invention.

  The quantity limiting valve is preferably arranged between the high pressure reservoir for fuel and the fuel injection nozzle.

  Further effective measures and preferred embodiments of the invention are derived from the dependent claims.

1 is a longitudinal sectional view of an embodiment of a quantity limiting valve according to the present invention. Schematic of a common rail system for a large diesel engine. The figure of the valve body of the Example of FIG. FIG. 2 is a view of the valve body of the embodiment of FIG.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, it is not according to the dimension but is shown by the schematic diagram partially in a section.

  FIG. 1 shows an embodiment of a volume-limiting valve according to the invention, indicated in the longitudinal section by the reference numeral 1 as a whole. The cross section is made along the longitudinal axis A of the quantity limiting valve 1.

  The quantity limiting valve 1 is a passive valve, meaning that it is not actively controlled or actuated by a control signal, for example, rather it opens and closes itself or automatically depending on the governing pressure difference.

  The passive quantity limiting valve 1 comprises a valve housing 2, which is here composed of two parts and includes a lower part 21 and a cover or upper part 22. The upper part 22 and the lower part 21 are fixed to each other by a plurality of screws 23. The valve housing 2 has an inlet 3 and an outlet 4 for a fluid medium. A valve chamber 5 in which a valve body 6 extending in the direction of the longitudinal axis A is arranged is provided in the valve housing 2 between the inlet 3 and the outlet 4.

  FIG. 3 shows another schematic view of the valve body 6 for better understanding. The two shaft ends are formed by two closing elements 63, 64, namely an inlet-side closing element 63 and an outlet-side closing element 64. These closing elements 63 and 64 are configured to perform sealing in cooperation with the valve seat 31 on the inlet side and the valve seat 41 on the outlet side, respectively. Both valve seats 31 and 41 are provided in the valve housing 2, that is, at the end of the valve chamber 5 on the outlet side or the end of the valve chamber 5 on the inlet side. The valve seats 31, 41 can be formed directly in the valve housing 2, or manufactured as a separate part and inserted into corresponding notches in the valve housing 2, for example by contraction, there Fixed. Manufacturing the valve seats 31 and 41 as separate parts is more effective depending on the application, because this gives rise to higher flexibility regarding the material. At this time, the valve seats 31 and 41 can be manufactured from a material different from that of the valve housing 2.

  In this embodiment, both the inlet and outlet valve seats 31 and 41 have conical surfaces 32 and 42, respectively. The conical surfaces 32 and 42 are on the inlet and outlet sides, respectively. Cooperates with the closure elements 63,64.

  The piston 7 is provided in the valve body 6 and is dimensioned such that its outer diameter is slidably guided through the wall of the valve chamber 5 with respect to its outer diameter. A slight gap is provided between the outside of the piston 7 and the wall of the valve chamber 5. FIG. 4 shows a view of the valve body 6 with the piston 7 for better understanding. The piston 7 is configured in a substantially cylindrical shape, and is arranged so that its cylinder axis coincides with the longitudinal axis A. The piston 7 has an end surface 71 on the side facing the inlet 3, and the other axial end of the piston 7 is open.

  The valve body 6 and the piston 7 can be constituted by one piece. However, it is usually more preferable from the viewpoint of technical production to manufacture the valve body 6 and the piston 7 as two separate components and subsequently connect them. The piston 7 can be manufactured, for example, from one or more parts of different materials, in order to ideally adapt its properties to the respective application or simplify manufacturing.

  In the embodiment described here, the end face 71 of the piston 7 is provided with a central hole 72 which serves to receive the valve body 6. The valve body 6 has a flange-shaped protrusion 65 that functions as a contact portion with respect to the end surface 71. The valve body 6 is pushed from the inside through the center hole 72 of the end surface 71 until the flange-shaped protrusion 65 abuts against the end surface 71 from the inside. In this respect, the dimensions are adapted to each other, so that the closing element 63 of the valve body 6 on the inlet side projects completely beyond the end face 71 of the piston 7 (see FIG. 4). In the embodiment described here, the piston 7 is contracted onto the valve body 6.

  According to the invention, at least one passage hole 73 extending in the axial direction through the end face 71 and parallel to the longitudinal axis A is provided in the end face 71 of the piston. In the present embodiment, a plurality of passage holes 73 are provided.

  Each passage hole 73 has a diameter d and a length L, which means the diameter that is decisive for the flow resistance, ie generally the smallest diameter of the passage hole 73.

  In addition, a plurality of holes 74 are provided in the jacket surface of the piston 7 and each extend radially through the wall of the piston 7. In this respect, the radial direction means a direction perpendicular to the axial direction, and the axial direction is determined by the longitudinal axis A. The fluid medium can exit through the hole 74 and reach the wall of the valve chamber 5, for example to provide lubrication of the piston 7.

  In particular, as shown in FIG. 1, the valve body 6 is biased toward the inlet side valve seat 31 by the spring 8 so that the inlet side closing element 63 is pressed against the inlet side valve seat 31. The spring 8 extends in the axial direction and is coaxial with the valve body 6, and the valve body 6 extends inside the spring 8. The spring 8 is supported around the valve seat 41 on the outlet side in the valve housing 2, and supported on the inner side at the end face of the piston 7.

  Before describing further details, the mode of operation of the volume limiting valve 1 should first be described. The quantity limiting valve 1 is suitable for a common rail system of a large diesel engine. In modern large diesel engines, there are usually multiple common rail systems, for example for fuel injection, gas exchange or auxiliary systems. In the following, reference is made to fuel injection applications. Large diesel engines are usually operated with heavy oil as fuel, ie the fluid medium is heavy oil in this case. As an additional fuel, marine diesel oil is often used, especially for engine operation in harbors, i.e. large diesel engines are typical when the ship sails before leaving the harbor or in the harbor area. It is operated with marine diesel oil. The operating temperature of fuel when operating with marine diesel oil is typically significantly lower than when operating with heavy oil. Variations in fuel viscosity will continue to occur.

  The quantity limiting valve 1 according to the present invention is suitable for heavy oil and can therefore be used in the fuel injection common rail system of large diesel engines. FIG. 2 shows a schematic diagram of a common rail system of such a large diesel engine. The system includes a high pressure pump 50 whereby fuel, or heavy oil, is conveyed into a pressure reservoir 51, also called an accumulator or rail. The pressure reservoir 51 is typically configured as a tubular component that extends along the engine at approximately the cylinder head level. The line 52 branches from the pressure storage unit, reaches the fuel injection nozzle 53, and supplies heavy oil to them. In FIG. 2, only one such line 52 and one fuel injection nozzle 53 is shown for reasons sufficient for understanding. The heavy oil in the pressure storage unit is a pressure that substantially corresponds to the injection pressure. This pressure is for example 1600 bar, but can also be higher, for example up to 2000 bar. For example, the quantity limiting valve 1 attached directly to or on the pressure storage unit 51 is provided between the pressure storage unit 51 and the line 52. The quantity limiting valve 1 is arranged such that its inlet 3 communicates with the pressure storage 51 and its outlet 4 communicates with the line 52.

  As long as the fuel injection nozzle 53 is not still injecting fuel into the cylinder, the amount limiting valve 1 is in the closed position shown in FIG. 1. In this case, the closing element 63 on the inlet side is connected to the valve seat 31 on the inlet side. Cooperate and seal to prevent heavy oil from passing through the volume limiting valve 1. In this state, substantially the same fluid pressure exists at the outlet 4 and the inlet 3 via heavy oil. The spring 8 biases the closing element 63 on the inlet side in a manner of sealing into the valve seat 31 on the inlet side.

  As soon as the fuel injection nozzle 53 begins to inject heavy oil into the combustion space of the cylinder, the pressure in the line 52 drops. This has the result that the valve body 6 moves upwards with the piston 7 in accordance with the illustration (FIG. 1), so that the inlet-side closing element 63 rises away from the inlet-side valve seat 31, and thus the pressure The heavy oil from the storage unit 51 can pass through the passage hole 73 and the amount limiting valve 1 and can flow into the line 52. The pressure difference required to open the communication at the valve seat 31 on the inlet side can be set by different measures, further explained below. This pressure difference is effectively set to a value from 2 bar to 20 bar. The pressure difference is set to a pressure larger than the pressure in the pressure storage unit 51 during the circulation operation.

  When the valve connection at the valve seat 31 on the inlet side is open, the stroke of the piston 7 depends on the amount of heavy oil injected and is at least approximately proportional. As soon as the injection process is finished, i.e. as soon as the fuel injection nozzle 53 is closed, the pressure in the line 52 rises again. As a result, the piston 7 moves and moves downward according to the drawing (FIG. 1) via the tension of the spring 8, and heavy oil can flow out through the passage hole 73. This movement ends when the inlet-side closure element 63 is urged in such a manner that it again seals into the inlet-side valve seat 31.

  The piston 7 reaches the maximum stroke when the amount of heavy oil determined as the maximum passes through the amount limiting valve 1. In a quantity limiting valve 1, during a normal or normal injection process, the maximum stroke of the piston 7 is usually insufficient to bias the outlet side closure element 64 into the outlet side valve seat 41 in a sealing manner. is there.

  For example, when the fuel injection nozzle 53 leaks or malfunctions downstream of the amount limiting valve 1, more heavy oil flows through the amount limiting valve 1 than in a normal injection process. This has the result that the piston continues its upward movement according to the illustration (FIG. 1) until the outlet-side closure element 64 is urged in a sealing manner into the outlet-side valve seat 41. As soon as this is done, no further heavy oil can flow through the volume limiting valve 1 into the line 52.

  For example, it may be desirable to disassemble the fuel injection nozzle 53 or the line 52 in the course of maintenance work. Large diesel engines are turned off for this purpose. Since the fuel does not cool and is therefore very viscous or almost solid and plugs the fuel supply system, it is usually circulated from the fuel container through the backflow line and the pressure reservoir 51 not shown in FIG. It is. This circulation operation usually occurs only with a roughing pump (not shown), i.e. the high-pressure pump 50 is not activated in this circulation operation. In the circulation operation, the pressure in the pressure storage unit 51 is typically 2 bar to 20 bar, for example 10 bar.

  If the pressure in pressure reservoir 51 drops to this value, line 62 can be depressurized and then disassembled. The pressure at the outlet 4 of the quantity limiting valve 1 thereby drops. However, the pressure difference for opening the communication between the valve seat 31 on the inlet side and the closing element 63 on the inlet side is set to be larger than the pressure during the circulation operation. In this example, the pressure difference is Since it is set at about 15 bar, the piston does not move, but rather the piston remains in the closed position shown in FIG.

  In order to simplify the disassembly of such a line 52 as much as possible, the pressure difference for opening the communication between the valve seat 31 on the inlet side and the closing element 63 on the inlet side is effectively between 2 and 20 bar. That is, it is set to a value larger than the pressure of the pressure storage unit 51 during the circulation operation. Thereby, heavy oil can be recirculated in a simple manner. The pressure difference of 2 bar to 20 bar means that the closing element 63 on the inlet side has a pressure on the end face 71 side of the bottom part as shown in FIG. Open only if this value between 2 and 20 bar is small.

  The main aspect of the quantity limiting valve 1 according to the present invention is that at least one passage hole 73 is provided in the end face 71 of the piston 7. Due to this measure, each passage hole 73 through which the fuel flows (or returned in the opposite direction) can be kept very short, so that the hydrodynamic flow resistance of the passage hole 73 is reduced. Independent of viscosity. Therefore, it is guaranteed that the amount of fuel for which the amount limiting valve is set is maintained constant even when the viscosity of the fuel fluctuates. Therefore, when the amount limiting valve 1 is set to a specific maximum amount, when the viscosity of the fuel changes or the viscosity changes, the amount of fuel that reaches this maximum value is also constant. This independence from viscosity means that a very accurate and invariant fuel limit for a particular value can be achieved, and this value is also not subject to any change when the viscosity varies.

  The hydrodynamic flow resistance of the passage hole is independent of the viscosity of the medium flowing therethrough and is particularly effective when the ratio of the length L of the passage hole 73 to the diameter d of the passage hole 73 is at most 4. Proved to be In this respect, the diameter d means the diameter d that is decisive for the flow resistance, and is generally the smallest diameter when the diameter varies over the length L.

  The operating pressure in the pressure storage 51 is very high, for example up to 1600 bar or 2000 bar, so that a very good sealing action is between the valve seat 31 on the inlet side and the closing element 63 on the inlet side or on the outlet side. It is inevitably important to be achieved between the valve seat 41 and the outlet-side closure element 64. For this purpose, the inlet-side closure element 63 or the outlet-side closure element 64, in particular both the inlet-side closure element 63 and the outlet-side closure element 64, are either the inlet-side valve seat 31 or the outlet-side valve seat. It has proved to be particularly effective to be configured to be in line contact with each of 41. Such line contact between the related is very efficient and is not particularly leaky. Furthermore, the line contact is very tolerable with respect to the rotation of the piston 7, i.e. a high sealing action is ensured even with a slight rotation of the piston or an error in the orientation.

  In this embodiment, the line contact is realized by both the valve seat 31 on the inlet side and the valve seat 41 on the outlet side, and each of the closing element 63 on the inlet side and the closing element 64 on the outlet side is the inlet side or the outlet side. Each of the valve seats 31, 41 has a spherical surface 631 or 641 which cooperates with the respective conical surface 32 or 42, respectively.

  The position of the line contact in the axial direction influences the pressure difference required to open the respective communication. For example, in the valve seat 31 on the inlet side, when the length of the line contact measured over the entire outer periphery becomes longer, the line contact becomes higher in the axial direction with respect to the picture in FIG. The greater the length of the line contact, the smaller the pressure difference required to open the communication. The pressure difference at which each communication is opened can therefore be set over the position of the line contact of the spherical surface 631 or 641, respectively.

  Since the preferred pressure differential is relatively small from 2 bar to 20 bar, it is desirable that the length of the line contact be large. This can be particularly ensured in that the center of curvature M of the spherical surface 631 or 641 is eccentric with respect to the longitudinal axis A of the valve body 6, respectively. This means that the center of curvature M, here the center of the sphere with the spherical surface 631 or 641, respectively, is on a straight line K parallel to the longitudinal axis A and spaced from the longitudinal axis A. A much smaller curvature can be achieved with this measure than when the center of curvature is on the longitudinal axis A.

  In many cases, the curvature is relatively small under actual performance aspects, but should effectively be large enough to ensure line contact between spherical surfaces 631 and 641 and conical surfaces 32 and 42, respectively. The length of each line contact and the pressure difference required to open it can be set via the magnitude of the spacing e at a given curvature.

  A further means that can be influenced or set with respect to the pressure difference required to open the respective communication is the selection of the elastic properties, in particular the elastic modulus of the spring 8.

  It is a further effective measure that the inlet side closing element 63 and the outlet side closing element 64 are at least identically configured with respect to the surfaces cooperating with the respective valve seats 31, 41. The automatic centering action of the valve body 6 can be realized by this symmetry. Simple centering of the valve body 6 is achieved by a slight gap between the jacket surface of the piston 7 and the wall of the valve chamber 5.

  Line contact between the inlet side valve seat 31 and the inlet side closure element 63 and between the outlet side valve seat 41 and the outlet side closure element 64 is another geometrical implementation of the cooperating surface, respectively. It can also be realized by example. For example, both of the cooperating surfaces can each be configured as a spherical surface, or both of the cooperating surfaces are each configured as a conical surface, particularly with a different cone angle.

  As mentioned above, all the passage holes 73 are preferably outside the spring 8 with respect to the axial direction, i.e. the distance between the central axis of the passage hole 73 and the longitudinal axis A is for each passage hole. It is larger than the radius of each passage hole 73 on the outer surface of the end surface 71 plus half of the outer diameter of the spring 8.

1 valve for limiting amount 2 valve housing 3 inlet 4 outlet 5 valve chamber 6 valve body 7 piston 8 spring 31, 41 valve seat 51 pressure storage 63, 64 closing element 71 end face 73 passage hole

Claims (14)

It is a passive volume control valve for large diesel engines,
A valve housing having an inlet and an outlet for the fluid medium and having a valve chamber disposed between the inlet and the outlet;
Valve bodies each having a closing element between the inlet side and the outlet side are arranged in the valve chamber, and the closing elements are configured to perform sealing in cooperation with the valve seats on the inlet side and the outlet side, respectively. And
The closing element on the inlet side is biased toward the valve seat on the inlet side by a spring,
Having a piston provided in the valve body, the outside of the piston is slidably guided through the wall of the valve chamber;
At least one passage hole through which a fluid medium can flow is provided in the end face of the piston ;
The valve of claim 3, wherein the valve body extends into the spring .   The quantity limiting valve of claim 1, wherein the ratio of the length of the passage hole to the diameter of the passage hole is 4 or less for each passage hole.   3. A quantity limiting valve according to claim 1 or 2, wherein the inlet side closure element is configured to be in line contact with the valve seat on the inlet side.   The amount limiting valve according to any one of claims 1 to 3, wherein the closing element on the outlet side is configured to be in line contact with the valve seat on the outlet side.   5. The quantity limiting valve according to claim 1, wherein the closing element on the inlet side or the outlet side has a spherical surface that cooperates with the valve seat on the inlet side or the outlet side.   The amount limiting valve according to claim 5, wherein a center of curvature of the spherical surface is eccentric with respect to a longitudinal axis of the valve body.   The amount limiting valve according to any one of claims 1 to 6, wherein the valve seat on the inlet side or the outlet side has a conical surface.   The quantity limiting valve according to any one of claims 1 to 7, wherein the closing elements on the inlet side and the outlet side have the same design. Said passage hole is arranged outside of the spring in the radial direction, the amount restriction valve according to any one of claims 1-8. Pressure differential to open the communication between the closure element of the valve seat and the inlet side of the inlet side is 20 bar 2 bar, the amount of according to any one of claims 1-9 Limit valve. It said piston is constructed as a separate component, the connected to the valve body, the amount restriction valve according to any one of claims 1-10. Said spring, said is supported by the end surface of the piston, the amount restriction valve according to any one of claims 1 to 11. A large diesel engine having the amount limiting valve according to any one of claims 1 to 12 . The large-sized diesel engine according to claim 13 , wherein the amount limiting valve is disposed between a high-pressure storage for fuel and a fuel injection nozzle.

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