High-pressure pump

Abstract

High-pressure pump (1) comprising a housing (2) with a pump cylinder (13) in which a pump piston (16) is arranged to move translationally up and down for conveying a pumped medium, wherein the pump piston (16) interacts directly or indirectly with a drive shaft (5) and at least one bearing of the drive shaft (5) is lubricated by means of a lubricant supplied through a line (21) and which is different from the pumped medium, wherein a control device (3) for maintaining a constant quantity of lubricant supplied to the high-pressure pump (1) is integrated into the line (21), wherein the lubricant is oil, wherein the control device (3) comprises a control throttle (40) actuated by a diaphragm (34), wherein the diaphragm (34) has a first lubricant-exposed pressure side with pressure surface A1 adjacent to a pressure chamber V1 and a second lubricant-exposed pressure side with pressure surface A2 adjacent to a pressure chamber V2,characterized in that the second printing side has a button (37) functioning as a control throttle (40) with the printing surface A3 interacting with a seat (38), wherein the button (37) interacts with the seat (38) comprising a discharge line (39) interacting with the line (21).

Description

[0001] The invention relates to a high-pressure pump comprising a housing with a pump cylinder in which a pump piston is arranged to move translationally up and down for conveying a pumped medium, wherein the pump piston interacts directly or indirectly with a drive shaft and at least one bearing of the drive shaft is lubricated by means of lubricant supplied through a line. State of the art

[0002] Such a high-pressure pump is known from DE 10 2012 218 083 A1. This high-pressure pump is specifically designed as a high-pressure fuel pump and has a housing that is designed as a universal housing for mounting on the crankcase of an internal combustion engine. The components of the high-pressure pump are arranged in the housing, in particular a pump cylinder in which a pump piston is arranged to move translationally up and down, as well as a drive shaft for generating the up and down movement of the pump piston. The drive shaft is rotatably mounted in a bearing located in the housing, and a lubricant in the form of oil is supplied to this bearing via a line. The lubricant is introduced directly from a crankcase line into the line in the housing.

[0003] The patent application DE 197 39 653 A1 discloses a method for producing and supplying fuel under high pressure, wherein part of the fuel delivered by a low-pressure pump is used to lubricate the high-pressure pump.

[0004] From the patent application DE 196 18 707 A1, a method and a device are known in which a fuel flow supplied by a feed pump of a high-pressure pump of an injection system is regulated as a function of a fuel volume flow.

[0005] German patent application DE 15 50 293 A discloses a fluid pressure regulator with a valve closure in a main flow path between inlet and outlet and with a diaphragm that carries the closure and is subjected to pressure in the outlet.

[0006] The invention is based on the objective of providing a high-pressure pump in which, for example, the lubrication of a drive shaft bearing is improved. Disclosure of the invention

[0007] This task is accomplished by incorporating a control device in the line to maintain a constant quantity of lubricant supplied to the high-pressure pump. This design is based on the understanding that using a lubricant different from the pumped medium allows for the specific lubrication requirements of the high-pressure pump's components to be addressed. A key aspect is that the bearings of the high-pressure pump's drive shaft are specifically lubricated, and the lubricant level in the pump's drive shaft housing is maintained at such a level that the drive shaft, or parts thereof, do not splash into the lubricant.It is important to consider that the lubricant supplied by the high-pressure pump must be discharged in a suitable manner so that it can then be pumped back into the line, for example, by a feed pump. However, due to changes in the lubricant's viscosity (e.g., temperature-dependent changes) and / or the quantity of lubricant supplied (e.g., at different operating speeds of the high-pressure pump and / or the feed pump), different quantities of lubricant may be supplied to the high-pressure pump via the line. By installing a control device in the line to maintain a constant quantity of lubricant supplied to the high-pressure pump, the disadvantages of an unregulated lubricant supply, as described above, are avoided. In particular, this prevents the high-pressure pump from receiving too little or too much lubricant.

[0008] Furthermore, the lubricant is oil. This oil can be supplied, in particular, by a machine to which the high-pressure pump is attached, so that no separate supply system with lubricating oil reservoir, oil pump and oil filter is necessary for the high-pressure pump.

[0009] Furthermore, the control device features a diaphragm-actuated control throttle. By adjusting the control throttle accordingly, a constant or at least nearly constant amount of oil is always supplied to the high-pressure pump, regardless of the viscosity or the flow rate.

[0010] Furthermore, the diaphragm has a first lubricated pressure side with a pressure surface A1 adjacent to a pressure chamber V1, and a second lubricated pressure side with a pressure surface A2 adjacent to a pressure chamber V2. Both pressure sides or pressure surfaces A1 and A2 interact with the associated pressure chambers V1 and V2, which in turn are appropriately connected to the line.

[0011] According to the invention, the second pressure side has a button functioning as a control throttle with the pressure surface A3, which in turn is further connected to a seat surface around a discharge line that interacts with the line leading to the high-pressure pump.

[0012] In one embodiment, a constant throttle, for example a laminar throttle, is provided in a supply line to the second pressure chamber V2, which interacts with the second pressure side of the membrane.

[0013] The control device trained in this way functions as follows: The line to the control unit is branched so that both pressure chambers V1 and V2 are filled with lubricant, allowing the lubricant pressure to act on both pressure surfaces A1 and A2 of the diaphragm. The first pressure surface A1 is directly connected to the line, ensuring that the unaffected inlet pressure prevailing in the line is maintained there. The second partial flow is routed through the constant throttle, thus limiting the lubricant flow to pressure surface A2 in pressure chamber V2. The lubricating oil flowing into pressure chamber V2 is then discharged from the control unit through the variable cross-section A3 of the control throttle, which is determined by the diaphragm. The constant throttle and the control throttle act as pressure dividers, ensuring that the pressure on the underside of the diaphragm in pressure chamber V2 is always lower than the pressure in the opposite pressure chamber V1.If, starting from a steady state, the rotational speed of a lubricating oil pump is increased, the delivery rate rises almost proportionally to the pump's rotational speed. This increases the pressure in pressure chamber V1 acting on pressure surface A1. The pressure on the underside of the diaphragm, with pressure surface A2 in pressure chamber V2, also increases. Since both pressure surface A2 and the pressure acting there are lower due to the pressure divider (smaller), the diaphragm is deflected downwards. This reduces the flow cross-section of the control throttle, so that the inflow rate into the discharge line leading to the high-pressure pump does not increase, or increases less than it would without the control device.

[0014] Conversely, as the rotational speed decreases, the diaphragm is deflected upwards, so that the cross-section A3 of the control throttle opens and the supply flow to the discharge line, and thus to the high-pressure pump, is reduced less or not at all than would be the case without a control device. Consequently, the control device designed according to the invention can significantly reduce or completely eliminate the dependence of the lubricant supply flow on the rotational speed of, for example, the lubricant pump, as well as on the viscosity of the lubricant. As a result, the lubricant level in the high-pressure pump or in a drive chamber of the high-pressure pump can be kept almost constant. The control device can be installed in various locations. One possibility is mounting it on the housing of the high-pressure pump or even integrating it into the housing of the high-pressure pump.Another option is to mount the control unit on the machine housing of the machine on which the high-pressure pump is installed. Alternatively, the control unit can be designed as a separate component and installed anywhere between the machine and the high-pressure pump. Mounting it near the lubricant pump is advisable.

[0015] In a further development of the invention, the membrane is a membrane spring. The membrane or membrane spring is made of an elastic material, for example a rubber-elastic material or a correspondingly flexible metallic material.

[0016] In a further development of the invention, the high-pressure pump is a high-pressure fuel pump of an internal combustion engine. This is the preferred embodiment and application, although other applications are also possible within the scope of the invention. If the high-pressure pump is a high-pressure fuel pump, it is designed to pump fuel required for the operation of the internal combustion engine. The high-pressure fuel pump, with its housing, is, for example, mounted on a crankcase of the internal combustion engine, and the drive shaft is driven directly by the engine. The lubricant in this case can be the engine oil required for its lubrication and cooling, with the oil being supplied by an engine oil pump to the various lubrication points of the engine and into the aforementioned line leading to the high-pressure fuel pump.The discharge line from the high-pressure fuel pump is then, for example, led directly into an oil sump of the internal combustion engine.

[0017] Further advantageous embodiments of the invention can be found in the drawing description, in which an embodiment of the invention shown in the figures is described in more detail.

[0018] They show: Fig. 1 a sectional view of a high-pressure pump, Fig. 2 a simplified representation of the system structure, in particular the lubrication supply of a high-pressure pump and Fig. 3 A view of the basic structure of a control device for maintaining a constant quantity of lubricant supplied to a high-pressure pump.

[0019] Fig. Figure 1 shows a sectional view of a high-pressure fuel pump 1 with a housing 2. The high-pressure fuel pump can be mounted directly to the crankcase of an internal combustion engine or operate separately from it in a suitable manner. The internal combustion engine is designed as a compression-ignition or spark-ignition engine and can therefore be operated, for example, with either diesel fuel or gasoline. When mounted to the crankcase, the crankcase has, for example, a cylindrical opening into which a drive shaft 5 of the high-pressure pump 1 projects. A drive mechanism for the drive shaft 5 is provided in the crankcase, extending from the opening 4. This drive mechanism can be, for example, a gearbox that connects the drive shaft 5 to a camshaft or other shaft of the internal combustion engine.In this embodiment, the drive shaft 5 is designed as a camshaft and has at least one cam 6. The drive shaft 5 is supported on both sides of the cam 6 in a bearing arrangement, for example, in the form of ball bearings 7a, 7b. The housing 2 is provided, for example, with a mounting flange 8, and the flange 8 has an annular groove 9 into which a round sealing ring 10 is inserted to seal the housing 2 against the environment.

[0020] Furthermore, the housing 2 of the high-pressure pump 1 has a mounting opening 11 into which a roller tappet 12 and a pump cylinder head 17 of the high-pressure pump 1, which includes a pump cylinder 13, are inserted. The roller tappet 12 has a tappet body 14 which carries a roller 15. The roller 15 rolls on the cam 6 of the drive shaft 5 and, during the rotation of the drive shaft 5, converts its rotational movement into a translational up-and-down movement of the roller tappet 12. A pump piston 16, which is movable up and down in the pump cylinder 13, interacts with the tappet body 14. During an upward movement, the pump piston 16 pumps fuel, which is located in a working chamber arranged in the pump cylinder head 17, via a lateral high-pressure outlet 18 and a high-pressure line, for example, into a high-pressure accumulator.

[0021] The plunger body 14 is pressed against the cam 6 of the drive shaft 5 by a spring 19, which is supported on the opposite side by the pump cylinder head 17. To prevent fuel from the pump working chamber from reaching oil-lubricated parts of the roller plunger 12 or the ball bearings 7a, 7b along the pump piston 16, the pump piston 16 is sealed against the pump cylinder 13 by means of a sealing element 20.

[0022] The ball bearings 7a, 7b and the roller tappet 12, which form the bearing of the drive shaft 5, are lubricated by a lubricant, for example, the oil of the internal combustion engine. The oil is supplied via a line 21, which branches into corresponding line sections within the housing 2 to the parts to be lubricated. A control device 3 is provided outside the housing 2, on the housing 2, or integrated into the housing 2. This device keeps the quantity of oil supplied constant, independent of the rotational speed of an oil pump 4, which could, for example, be the oil pump 4 of the internal combustion engine.

[0023] The housing 2 contains a motor chamber 22, into which the cam 6 of the drive shaft 5 projects. The motor chamber 22 is connected to a drain line 23, through which the oil collecting in the motor chamber 22 is drained and, for example, fed to the oil sump of the internal combustion engine.

[0024] Fig. Figure 2 shows the system structure of the high-pressure pump 1, including the fuel supply and oil supply, and incorporating the control unit 3. Fuel is supplied to the high-pressure pump 1 from a fuel tank 24 by a pre-supply pump 25, via a metering unit 26 and an inlet valve 27, into the aforementioned working chamber. During the upward movement of the pump piston 16, the fuel is conveyed through the high-pressure outlet 18 and an outlet valve 28 into a high-pressure accumulator 29. From there, the stored fuel is drawn for injection into the combustion chambers of the internal combustion engine. For example, the oil pump 4 delivers oil from the oil sump 30 or a dry sump reservoir of the internal combustion engine through line 21 to the high-pressure pump 1. The control unit 3, which will be described below, is installed in this line 21.The engine room 22 of the high-pressure pump 1 is connected to the discharge line 23, which in turn leads into the oil sump 30.

[0025] Fig. Figure 3 shows the structure of the control device 3, which comprises a control device lower part 32 and a control device upper part 33. A diaphragm 34 is tightly clamped between the control device lower part 32 and the control device upper part 33. A pressure chamber V1 is located in the control device upper part 33, and a pressure chamber V2 is located in the control device lower part 32. Both pressure chambers V1 and V2 border corresponding pressure surfaces A1 and A2 of the diaphragm 34. The pressure chamber V1 is directly connected to line 21 via a supply line 35a, while the pressure chamber V2 is connected to line 21 via a supply line 35b with an integrated constant throttle 36. Contrary to the illustration in Figure 3, the supply lines 35a and 35b can be connected in different ways. Fig.3 be completely embedded in the lower part 32 and the upper part 33 of the control device. Likewise, the constant throttle 36 can also be embedded in the lower part 32 of the control device.

[0026] The diaphragm 34 has a button 37 with a pressure surface A3 on the side of the pressure surface A2 in the pressure chamber V2, which interacts with a seat 38 in the control unit base 32. The seat 38 surrounds a discharge line 39 in the control unit base 32, the discharge line 39 being connected to the downstream line 21 to the oil supply of the high-pressure pump 1. In particular, the button 37 with the pressure surface A3, together with the seat 38, forms a control throttle 40, which is actuated by the diaphragm 34. The function of the control unit 3 is described in detail in the general section of the description.

Claims

[1] High-pressure pump (1) comprising a housing (2) with a pump cylinder (13) in which a pump piston (16) is arranged to move translationally up and down for conveying a pumped medium, wherein the pump piston (16) interacts directly or indirectly with a drive shaft (5) and at least one bearing of the drive shaft (5) is lubricated by means of a lubricant supplied by a line (21) and which is different from the pumped medium, wherein a control device (3) for maintaining a constant quantity of lubricant supplied to the high-pressure pump (1) is integrated into the line (21), wherein the lubricant is oil, wherein the control device (3) comprises a control throttle (40) actuated by a diaphragm (34), wherein the diaphragm (34) has a first lubricant-exposed pressure side with pressure surface A1 adjacent to a pressure chamber V1 and a second lubricant-exposed pressure side with pressure surface A2 adjacent to a pressure chamber V2,characterized by , that the second printing side has a button (37) acting as a control throttle (40) with the printing surface A3 interacting with a seat (38), wherein the button (37) interacts with the seat (38) comprising a discharge line (39) interacting with the line (21). [2] High pressure pump (1) according to claim 1, characterized by , that a supply line (35b) cooperating with the line (21) to the pressure chamber V2 has a constant throttle (36). [3] High pressure pump (1) according to one of claims 1 or 2, characterized by , that the diaphragm (34) is a diaphragm spring. [4] High-pressure pump (1) according to any one of the preceding claims, characterized by that the high-pressure pump is a high-pressure fuel pump of an internal combustion engine.

Images