KR20140034195A - Hydraulic system and operating method - Google Patents

Abstract

The hydraulic system includes a first subsystem (23) that operates within a first pressure range, and a second subsystem (24) that operates within a second pressure range, wherein the upper limit of the second pressure range 1 higher than the upper limit of the pressure range. The hydraulic system includes a pump 2 for supplying hydraulic fluid to the hydraulic system, and a first booster 10 and a second booster 10 'for increasing the pressure of the second subsystem. The booster (10, 10 ') is a piston-type booster with at least two alternative incremental rates. The present invention also relates to a method of operating a hydraulic system.

Description

HYDRAULIC SYSTEM AND OPERATING METHOD [0001]

The present invention relates to a hydraulic system according to the preamble of claim 1. The present invention also relates to a method of operating a hydraulic system.

Efficiency and low component cost are important features of hydraulic systems. Many different machines, such as large internal combustion engines, may include several hydraulic circuits with different pressure and flow requirements. Often this means that several pumps are needed to create a hydraulic fluid flow at different pressure levels, which increases the cost of the system. Another problem is that pumps capable of producing high pressures and flow are often of low efficiency. Although highly efficient pumps can be used, they are much more expensive. In addition to having several hydraulic circuits with different pressure requirements, it is also common for certain hydraulic circuits to require different pressures and flows in different operating modes, which makes the system more complex.

It is an object of the present invention to provide an improved hydraulic system. The characteristic function of the system according to the invention is given in the characterizing part of claim 1. It is another object of the present invention to provide an improved method of operating a hydraulic system. The characteristic function of the method is given in the characterizing part of another independent claim.

The hydraulic system according to the invention comprises at least a first subsystem operating in a first pressure range and a second subsystem operating in a second pressure range. The upper limit of the second pressure range is higher than the upper limit of the first pressure range. The hydraulic system further includes a pump for supplying hydraulic fluid to the system at a first pressure level and two boosters for increasing the pressure of the second subsystem to a second pressure level. The booster is a piston-type booster with at least two alternative rates of increase.

With the hydraulic system according to the invention, the same pump can be used to supply hydraulic fluid to the two subsystems with different pressure requirements. The maximum output pressure of the pump can be selected according to the lower pressure requirements, which reduces the cost of the system. Due to the two boosters having an alternative rate of increase, the second subsystem can be supplied with a stable flow at different pressures.

The method according to the invention relates to the operation of a hydraulic system, said hydraulic system comprising at least a first subsystem operating in a first pressure range and a second subsystem operating in a second pressure range, wherein The upper limit of the second pressure range is higher than the upper limit of the first pressure range. The method includes at least a first operating mode comprising a first step wherein in the first step the plunger of the first booster is moved to pressurize the fluid in the second chamber of the first booster and pressurize the pressurized fluid The hydraulic fluid is introduced into the first chamber of the first booster and the plunger of the second booster is moved to empty the first and third chambers of the second booster A hydraulic fluid is introduced into the second chamber of the second booster. Wherein the first operating mode further comprises a second step wherein in the second step the plunger of the second booster is moved to pressurize the fluid in the second chamber of the second booster and pressurize the pressurized fluid to the second sub- A hydraulic fluid is introduced into the first chamber of the second booster and a hydraulic fluid is introduced into the first chamber to move the plunger of the first booster to empty the first and third chambers of the first booster. And introduced into the second chamber of the first booster.

In the method according to the invention, the plunger of one of the plumes of the two booster is always used to supply fluid to the second subsystem, unless the booster is in bypass mode, so that stable flow at constant pressure May be supplied to the second subsystem. The evacuation steps of the first chamber and the third chamber may be used for reloading the thickener or for supplying fluid from the third chamber to the second subsystem.

According to an embodiment of the present invention, each pressure intensifier in the system has a plunger including a first pressure side, a second pressure side, and a third pressure side. The first pressure surface and the third pressure surface are on the same side of the plunger in the direction of movement of the plunger. The wall of the intensifier defines a first chamber having a first pressure surface, a second chamber having a second pressure surface, and a third chamber having a third pressure surface. Each chamber may be connected to an outlet of a pump for receiving hydraulic fluid. The second chamber and the third chamber are further connected to the second subsystem to supply the hydraulic fluid to the second subsystem.

According to another embodiment of the present invention, the ratio between the area of the first pressure surface and the area of the second pressure surface is at most 2% different from the ratio between the area of the second pressure surface and the area of the third pressure surface. With this option, the movement of the plunger in both directions can be used to create a flow at essentially the same pressure level.

According to another embodiment of the present invention, the ratio between the combined area of the first pressure surface and the third pressure surface and the area of the second pressure surface is greater than the ratio between the area of the second pressure surface and the area of the third pressure surface Up to 2% different.

According to another embodiment of the present invention, the system includes means for opening and closing fluid communication between the first chamber of the booster and the pump, and means for opening and closing the fluid interlock between the third chamber and the pump.

According to another embodiment of the present invention, the first subsystem and the second subsystem comprise parts of an internal combustion engine. In another embodiment of the invention, the first subsystem comprises a gas exchange valve of an internal combustion engine and the second subsystem comprises a fuel injector of an internal combustion engine.

According to another embodiment of the present invention, the pump is a variable displacement pump.

According to an embodiment of the present invention, the method includes a second mode of operation. The second mode of operation includes the first step, wherein in the first step, the plunger of the first booster is moved to pressurize the fluid in the second chamber of the first booster and pressurize the pressurized fluid in the first mode of operation Hydraulic fluid is introduced into the first chamber and the third chamber of the first booster and the second chamber of the second booster is evacuated to emptify the first chamber and the third chamber of the second booster, Hydraulic fluid is introduced into the second chamber of the second booster to move the plunger of the second booster. The second mode of operation further includes a second step wherein in the second step the plunger of the second booster is moved to pressurize the fluid in the second chamber of the second booster and pressurize the pressurized fluid to the first operation Mode hydraulic fluid is introduced into the first and third chambers of the second booster and the first and third chambers of the first booster are emptied, Hydraulic fluid is introduced into the second chamber of the first booster to move the plunger of the first booster.

According to another embodiment of the present invention, in the second operating mode, the third chamber is filled and emptied through the same line. When the fluid is not discharged to the tank through the return line, the energy stored by the fluid in the third chamber can be recovered.

1 shows a hydraulic system according to an embodiment of the present invention.
Figures 2a-2e illustrate a portion of the system of Figure 1 in different stages of the operating cycle.
3 shows a hydraulic system according to another embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

1 shows a hydraulic system according to an embodiment of the present invention. The hydraulic system is used to operate a large-scale internal combustion engine, for example a main or auxiliary engine of a ship, a gas exchange valve and a fuel injector of an engine or to generate electricity in a power plant. The hydraulic system includes a tank (1) for storing hydraulic fluid and a pump (2) for pressurizing the hydraulic fluid and supplying the pressurized fluid to the hydraulic circuit. The pump 2 is a variable displacement pump capable of controlling the flow. The system is also equipped with a first accumulator (4) for reducing pressure fluctuations in the circuit and thus helping to maintain a stable pressure in the system. In addition, there is a pressure relief valve 3 in the system to prevent overpressure.

The gas exchange valve forms a first subsystem 23 requiring a first pressure range, i.e., 235 to 350 bar. Thereafter, the required flow may be about 64 l / min. The fuel injector forms a second subsystem 24 requiring a second pressure range, i.e., 250 to 700 bar. Thus, the upper limit of the pressure range required by the second subsystem 24 is higher than the upper limit of the pressure range required by the first subsystem 23. The average flow required for the second subsystem 24 may be about 36 l / min. The pump 2 is selected to satisfy the pressure requirements of the first subsystem 23 and the flow requirements of the entire hydraulic system.

In order to increase the pressure of the hydraulic fluid towards the second subsystem 24, the system is provided with a first booster 10 and a second booster 10 '. The hydraulic fluid is directed from the output pressure of the pump 2 to the first subsystem 23. Each of the pressure intensifiers 10, 10 'includes a reciprocating plunger 11, 11'. The walls of the intensifiers 10 and 10 'and the plungers 11 and 11' define the first chambers 12a and 12a ', the second chambers 12b and 12b' and the third chambers 12c and 12c ' do. The first chambers 12a and 12a 'and the third chambers 12c and 12c' are on the same side of the plungers 11 and 11 'in the moving direction of the plungers 11 and 11'. The second chamber 12b, 12b 'is on the opposite side. Fluid ports 10a, 10a ', 10b, 10b', 10c, 10c 'for introducing fluid into and out of the chamber are provided in each of the chambers 12a, 12a', 12b, 12b ', 12c, 12c' / RTI > The first pressure lines 18 and 18 'on which the first on-off valves 6 and 6' are mounted connect the first chambers 12a and 12a 'to the pump 2. The first chambers 12a and 12a 'are also connected to the tank 1 by a first return line 19 and 19' on which the second on-off valves 7 and 7 'are mounted. The second chambers 12b and 12b 'are connected to the pump 2 by second pressure lines 20 and 20' on which the first check valves 13 and 13 'are mounted. The third chamber 12c, 12c 'is connected to the pump 2 by a third pressure line 21, 21' comprising a third on-off valve 8, 8 '. The third return line 22, 22 'connects the third chamber 12c, 12c' to the tank 1. In addition, the intensifier 10, 10 'includes a fourth chamber 12d, 12d' which is opposite to the first chamber 12a, 12a '. In the embodiment described herein, the fourth chamber 12d, 12d 'is not used for pressure increase. However, in the fourth chamber 12d, 12d ', a pressure line may be mounted if a further alternative rate of increase is required. Leak lines 17 and 17 'connect the fourth chambers 12d and 12d' to the tank 1.

The second check valve 14, 14 'is disposed in the line 28, 28' leading from the second chamber 12b, 12b 'to the fuel injector and the third check valve 15, 15' (29, 29 ') leading from the fuel injector (12c, 12c') to the fuel injector. The fourth check valve 16, 16 'is disposed between the third chamber 12c, 12c' and the third on-off valve 8, 8 '.

The plungers 11, 11 'have three separate pressure surfaces. The first pressure surfaces A1, A1 'are in contact with the fluid in the first chamber 12a, 12a'. The second pressure surfaces A2 and A2 'are in contact with the fluid in the second chambers 12b and 12b' and the third pressure surfaces A3 and A3 'are in fluid contact with the fluid in the third chambers 12c and 12c' As shown in Fig. The size of the pressure surface is such that the area of the first pressure surface A1 divided by the area of the second pressure surface A2 is less than the second pressure divided by the area of the third pressure surface A3 within the manufacturing tolerance Is equal to the area of the surface A2, that is, A1 / A2 = A2 / A3. The allowable difference depends on the application. In the embodiment described herein, the difference between ratios A1 / A2 and A2 / A3 should be at most 2%, more preferably less than 1%, most preferably less than 0.5%.

The operating principle of the hydraulic system is described in more detail with reference to Figures 2a to 2e.

Figure 2A shows a situation in which the plunger 11 of the first booster 10 moves upward, i.e. towards the second fluid port 10b. The term "upward" refers only to the figures here, and the actual intensifier 10 can be arranged to operate in any direction. The pump 2 supplies the hydraulic fluid from the tank 1 to the hydraulic circuit at a constant pressure. In this embodiment, the pressure is in the range of 235 to 350 bar. The first on-off valve 6 of the pressure line 18 of the first chamber 12a is opened to allow flow into the pressure vessel 10. [ The fluid enters the first chamber 12a of the pressure vessel 10 through the first fluid port 10a. The second on-off valve 7, which is disposed in the return line 19 of the first chamber 12a, is kept closed to prevent fluid from flowing directly into the tank 1. In addition, the third on-off valve 8 of the pressure line 21 of the third chamber 12c is closed and held. The fourth on-off valve 9 of the return line 22 of the third chamber 12c is adapted to remove fluid from the tank 1 to fill the void space created by the upward movement of the plunger 11. [ 3 chamber 12c. ≪ / RTI > Apart from the embodiment shown in the figures, the fluid source to which the fluid is supplied to the third chamber 12c may be different from the tank 1. For example, in an internal combustion engine, the fluid source may be a fluid line connected to a lubricating pump. The pressurized hydraulic fluid in the first chamber 12a pushes the plunger 11 upward. Correspondingly, the pressure in the second chamber 12b increases. The ratio between the pressure in the first chamber 12a and the pressure in the second chamber 12b is inversely proportional to the ratio between the area of the first pressure surface A1 and the area of the second pressure surface A2. In this embodiment, the pressure rises theoretically to a level of 341 to 508 bar. The first check valve 13 prevents the fluid at a pressure higher than the pressure produced by the pump 2 from flowing to the pump 2. The second check valve 14 allows fluid to flow into the fuel injector.

2B shows a situation in which the plunger 11 moves downward, that is, toward the third fluid port 10c. The first on-off valve 6 is closed to prevent flow in the pressure line 18 of the first chamber 12a. In addition, the third on-off valve 8 is closed to prevent the flow in the pressure line 21 of the third chamber 12c. The first check valve 13 allows fluid flow to the second chamber 12b through the second pressure line 20 and the second fluid port 10b. The fluid in the second chamber 12b pushes the plunger 11 downward. The second on-off valve 7 in the return line 19 of the first chamber 12a is kept open to allow fluid to flow freely from the first chamber 12a to the tank 1 . Therefore, the pressure level in the first chamber 12a is equal to the pressure of the tank 1, i.e., the ambient pressure. The fourth on-off valve 9 of the return line 22 of the third chamber 12c is closed to prevent fluid flow from the third chamber 12c to the tank 1. Thus, the fluid in the third chamber 12c flows through the third check valve 15 to the fuel injector. The fourth check valve 16 protects the third on-off valve 8 from the high pressure of the booster 10. Thus, the third on-off valve 9 can have a lower permitted maximum pressure, which reduces the cost of the hydraulic system. Since the ratio between the area of the first pressure face and the area of the second pressure face A1, A2 is equal to the ratio between the area of the second pressure face and the area of the third pressure face A2, A3, As shown in Fig. 2A and 2B, the pressure builder 10 operates in a medium pressure mode. In the medium pressure mode, the intensifier 10, 10 'acts as a bi-directional intensifier that supplies the pressurized fluid to the system in both directions of movement.

2C shows a situation in which the plunger 11 moves upward. Both the first on-off valve 6 in the pressure line 18 of the first chamber 12a and the third on-off valve 8 in the pressure line 21 of the third chamber 12c Lt; / RTI > Thus, the hydraulic fluid from the pump 2 can flow into the first chamber 12a and the third chamber 12c. The second on-off valve 7 of the return line 19 of the first chamber 12a and the fourth on-off valve 9 of the return line 22 of the third chamber 12c are fluid Is closed to prevent direct flow to the tank (1). The fluid in the first chamber 12a and the third chamber 12c pushes the plunger 11 upward. Thus, the pressure in the second chamber 12b is increased. The pressure increase is proportional to the ratio between the combined area of the first pressure surface and the third pressure surface (A1, A3) and the area of the second pressure surface (A2). Therefore, the pressure is higher than in the situation of FIGS. 2A and 2B, and in this embodiment is 503 to 749 bar. The first check valve 13 prevents flow from the second chamber 12b to the pump 2 and thus the fluid flows through the second check valve 14 to the fuel injector.

Fig. 2D shows a situation in which the plunger 11 moves downward. The first on-off valve 6 in the pressure line 18 of the first chamber 12a and the third on-off valve 8 in the pressure line 21 of the third chamber 12c Lt; / RTI > The fluid thus flows from the pump 2 to the second chamber 12b and pushes the plunger 11 downward. The second on-off valve 7 in the return line 19 of the first chamber 12a and the fourth on-off valve 9 in the return line 22 of the third chamber are kept open , So that the fluid can freely flow from the first chamber 12a and the third chamber 12c to the tank 1. This is a reloading phase, during which the booster 10 does not produce any pressure on the fuel injector. Operation of the pressure vessel 10 of Figures 2c and 2d forms a high pressure mode. In the high pressure mode, the intensifiers 10, 10 'act as unidirectional boosters, which supply the pressurized fluid to the system only in one direction of movement and the other direction of movement of the plungers 11, 11' 10, 10 ').

2E, the plunger 11 is at the bottom of the plunger, i.e. at the end where the third fluid port 10c is located. The first on-off valve 6 is closed to prevent flow to the first chamber 12a. The third on-off valve 8 may be open to allow flow to the third chamber 12c, but fluid may flow through the first check valve 13 into the second chamber 12b, 2 Because the area of the pressure surface A2 is larger than the area of the third pressure surface A3, the plunger 11 is not moved upward. The fourth on-off valve 9 prevents fluid from flowing from the pressure line 21 of the third chamber 12c to the tank 1 through the return line 22 of the third chamber 12c Is closed. The fluid thus flows through the two paths, namely through the first check valve and the second check valve 13, 14 and through the third on-off valve 8 and the fourth check valve and the third check valve 16 , 15) to the fuel injector. The third on-off valve 8 can also be closed. In this case, the fluid may only flow through the first check valve and the second check valve (13, 14). The second on-off valve 7 can also be opened. If the pressure loss in the system is neglected, this is the bypass mode in which the pressure in the fuel injector is equal to the pressure in the pump 2. When the first on-off valve 6 is not opened after the downward movement of the plunger 11, the upward movement of the plunger 11 is prevented and the pressure vessel 10 is switched to the bypass mode.

Only the function of the first booster 10 has been described above. The second booster 10 'operates in the same way, but it is arranged to operate in a different phase than the first booster 10. When a medium-high pressure is required in the fuel injector, the pressure builder 10, 10 'operates in the operating mode of FIGS. 2A and 2B. When the pressure line 18 to the first chamber 12a of the first booster 10 is open and the plunger 11 moves upwardly, the first and second chambers of the second booster 10 ' The pressure lines 18 ', 21' to the first and second pressure boosters 12a ', 12c' are closed and the plunger 11 'of the second booster 10' moves downward. And the return line 22 'of the third chamber 12c' of the second booster 10 'is closed. Both the pressure intensifiers 10 and 10 'supply fluid to the fuel injector at the same pressure. The second booster 10 'may also be operated in the manner described in Figure 2D. In this case, the return line 22 'of the third chamber 12c' of the second booster 10 'may be open and the second booster 10' may generate any pressure on the fuel injector Can not. When the plunger 11, 11 'reaches its end position, the associated valves are switched to another position to change the direction of movement of the plunger 11, 11'. Due to the second accumulator 5, the plungers 11, 11 'of the first and second co-intensifiers 10, 10' can be in opposite stages and can simultaneously change their direction of movement. The second accumulator (5) ensures that the fluid supply to the second subsystem (24) is not interrupted. However, the intensifiers 10, 10 'can be arranged and operated such that the plungers 11, 11' do not reach their end positions at the same time. In this way, the interruption of the fluid supply caused by the change of the moving direction of the plunger 11, 11 'can be avoided.

When a high pressure is required for the fuel injector, the pressure builder 10, 10 'operates in the operating mode of Figures 2c and 2d. The pressure lines 18 and 21 of the first and third chambers 12a and 12c of the first booster 10 are opened and the plunger 11 of the first booster 10 is opened to the high pressure The second booster 10 'is in the reloading phase of Figure 2d. Therefore, the pressure lines 18 ', 21' to the first and third chambers 12a ', 12c' of the second booster 10 'are closed and the plunger 11' of the second booster 10 ' ') Moves downward. When the position of the associated valve is switched, the moving direction of the plunger 11, 11 'is also changed. The change from the pressure supply step to the reloading step can be done when the plunger 11, 11 'reaches its end position. The period of the reloading step is shorter than the period of the pressure supply step so that the plunger 11, 11 'is reloaded until the other plunger 11, 11' in the pressure supply step reaches its end position Step < / RTI > mode of FIG. 2E. The booster 10, 10 'may be equipped with a position sensor which is used to determine the appropriate time for switching the position of the associated on-off valve.

If no pressure intensifier is required, the plungers 11, 11 'of both the pressure vessels 10, 10' can be operated in the bypass mode of FIG. 2e.

The second accumulator 5 is disposed upstream from the fuel injector between the first booster 10 and the second booster 10 '. The purpose of the second accumulator 5 is to reduce the pressure fluctuations and to prevent the interruption of the fluid supply when the plungers 11, 11 'of the pressure builders 10, 10' change their direction of movement.

The embodiment shown in Fig. 3 operates in the same manner as the embodiment shown in Figs. 1 to 2E. Although the first accumulator 4 and the pressure relief valve 3 are not shown in Fig. 3, these devices may also be provided in this embodiment. The main difference between the embodiments is that the return line 22, 22 'from the third chamber 12c, 12c' in the system of Figure 3 is provided with a fifth check valve 25 , 25 'are mounted. Thus, when the plunger 11, 11 'is driven upward by introducing fluid into the first chamber 12a, 12a', only the return line 22, 22 ' It is used to suck. Therefore, the fourth on-off valve 9, 9 'is not required. In the reloading phase, the third chamber 12c, 12c 'is emptied through the third pressure line 21, 21'. An advantage of this arrangement is that the energy stored by the fluid in the third chambers 12c, 12c 'is recovered. Since the third pressure line 21, 21 'must permit flow in both directions, a fourth check valve 16 (16') is provided between the third on-off valve 8, 8 'and the pressure- , 16 'are not mounted. Instead, there is a sixth check valve 26, 26 'on the other side of the third on-off valve 8, 8'. The throttle valves 27 and 27 'are arranged in parallel with the sixth check valves 26 and 26' in order to equalize the flow from the pump 2 to all of the plungers 11 and 11 '. The function of the throttle valve 27, 27 'prevents the situation where most of the pump flow is directed only to one of the plungers 11, 11'. The sixth check valve 26, 26 'allows flow from the pump 2 to the pressurizer 10, 10', but not in the other direction. When the third chamber 12c, 12c 'is emptied during the reloading phase, the fluid flows through the throttle valve 27, 27'.

According to a further embodiment of the present invention the size of the pressure surface is such that the combined area of the first pressure surface A1 and the third pressure surface A3 divided by the second pressure surface A2 is within the manufacturing tolerance Is equal to the area of the second pressure surface A2 divided by the area of the third pressure surface A3, that is, (A1 + A3) / A2 = A2 / A3. With this option, the pressure intensifier 10, 10 'can supply fluid at high pressure to the fluid injector 24 during both upward and downward movement of the plunger 11, 11'. The medium pressure fluid is supplied to the fluid injector 24 when the fluid is introduced into the first chamber 12a, 12a 'of the pressure builder 10, 10'. Thus, Figures 2b and 2c may show the high pressure mode of the pressure vessel 10, and Figures 2a and 2d may show the medium pressure mode. In this embodiment, the booster 10, 10 'operates as a bidirectional booster in the high pressure mode and as a unidirectional booster in the medium pressure mode.

It will be apparent to those skilled in the art that the present invention is not limited to the embodiments described above, but may vary within the scope of the appended claims. For example, the hydraulic system need not be used in an internal combustion engine, but can be used to operate any hydraulic device that requires different pressure levels. Also, it is possible to select the area of the pressure surface differently from the above-described manner. Thus, it is possible to obtain more than two different rates of increase.

Claims (12)

As a hydraulic system,
- a first subsystem (23) operating in a first pressure range, and
- at least a second subsystem (24) operating within a second pressure range,
Wherein the upper limit of the second pressure range is higher than the upper limit of the first pressure range,
The hydraulic system
A pump (2) for supplying hydraulic fluid to the hydraulic system at a first pressure level; And
- a first booster (10) and a second booster (10 ') for increasing the pressure of said second subsystem to a second pressure level,
Characterized in that the first booster (10) and the second booster (10 ') are piston-type booster with at least two alternative rates of increase. The method according to claim 1,
Each pressure intensifier 10, 10 'includes a plunger 11, 11'
The plunger 11, 11 '
The first pressure face (A1, A1 '),
- a second pressure face (A2, A2 '), and
- a third pressure surface (A3, A3 '),
The first pressure surfaces A1 and A1 'and the third pressure surfaces A3 and A3' are on the same side of the plunger 11 and 11 'in the moving direction of the plunger 11 and 11'
The wall of the booster 10, 10 '
- a first chamber (12a, 12a ') with said first pressure surface (A1, A1'),
- a second chamber (12b, 12b ') with said second pressure surface (A2, A2'), and
- defining a third chamber (12c, 12c ') with said third pressure surface (A3, A3'),
Each of the chambers 12a, 12a ', 12b, 12b', 12c and 12c 'can be connected to the outlet of the pump 2 for receiving hydraulic fluid and the second chamber 12b, 12b' And the third chamber (12c, 12c ') is further connected to the second subsystem (24) for supplying hydraulic fluid to the second subsystem (24). 3. The method of claim 2,
Wherein the ratio between the area of the first pressure surface (A1, A1 ') and the area of the second pressure surface (A2, A2') is greater than the area of the second pressure surface (A2, A2 ' Is different from the ratio between the areas of the surfaces (A3, A3 ') by at most 2%. 3. The method of claim 2,
The ratio between the combined area of the first pressure surface (A1, A1 ') and the third pressure surface (A3, A3') and the area of the second pressure surface (A2, A2 ' Is at most 2% different from the ratio of the area of the surfaces (A2, A2 ') to the area of the third pressure surfaces (A3, A3'). 5. The method according to any one of claims 2 to 4,
The hydraulic system comprises means (6, 6 ') for opening and closing fluid communication between the first chamber (10a, 10a') of the booster (10, 10 ') and the pump (2) And means (8, 8 ') for opening and closing fluid communication between the chamber (10c, 10c') and the pump (2). 6. The method according to any one of claims 1 to 5,
Wherein said first subsystem and said second subsystem (23, 24) comprise parts of an internal combustion engine. The method according to claim 6,
Characterized in that said first subsystem (23) comprises a gas exchange valve of said internal combustion engine and said second subsystem (24) comprises a fuel injector of said internal combustion engine. 8. The method according to any one of claims 1 to 7,
Characterized in that the pump (2) is a variable displacement pump. A method of operating a hydraulic system,
The hydraulic system
- a first subsystem (23) operating in a first pressure range, and
- at least a second subsystem (24) operating within a second pressure range,
Wherein the upper limit of the second pressure range is higher than the upper limit of the first pressure range,
The method includes at least a first operating mode having a first phase,
In the first step,
- moving the plunger (11) of the first booster (10) to pressurize the fluid in the second chamber (12b) of the first booster (10) and apply the pressurized fluid to the second subsystem A hydraulic fluid is introduced into the first chamber 12a of the first booster 10,
A hydraulic fluid (not shown) to move the plunger 11 'of the second booster 10' to empty the first chamber 12a 'and the third chamber 12c' of the second booster 10 ' Is introduced into the second chamber 12b 'of the second booster 10'
Wherein the first mode of operation further comprises a second step,
In the second step,
- moving the plunger (11 ') of the second booster (10') to pressurize the fluid in the second chamber (12b ') of the second booster (10' 2 subsystem 24, hydraulic fluid is introduced into the first chamber 12a 'of the second booster 10'
Hydraulic fluid is introduced into the first chamber (12) to move the plunger (11) of the first booster (10) to empty the first chamber (12a) and the third chamber (12c) Is introduced into the second chamber (12b) of the first booster (10). 10. The method of claim 9,
Movement of the plunger 11, 11 ', which empties the first chamber 12a, 12a' and the third chamber 12c, 12c ', causes fluid in the third chamber 12c, 12c' And to supply the pressurized fluid to the second subsystem (24). 10. The method of claim 9,
The method comprising a second mode of operation comprising a first step,
In the first step
- moving the plunger (11) of the first booster (10) to pressurize the fluid in the second chamber (12b) of the first booster (10) and pressurize the pressurized fluid in the first operating mode Hydraulic fluid is introduced into said first chamber (12a) and said third chamber (12c) of said first booster (10) to supply said second subsystem (24)
- moving said plunger (11 ') of said second booster (10') to empty said first chamber (12a ') and said third chamber (12c') of said second booster (10 ' A hydraulic fluid is introduced into the second chamber 12b 'of the second booster 10'
The second mode of operation further comprises a second step,
In the second step
- moving the plunger (11 ') of the second booster (10') to pressurize the fluid in the second chamber (12b ') of the second booster (10' Hydraulic fluid is supplied to the first chamber 12a 'of the second booster 10' and the third chamber 12a 'of the second booster 10' to supply the second sub-system 24 with a higher pressure than in the first operating mode. 12c '
A hydraulic fluid is supplied to move the plunger (11) of the first booster (10) to empty the first chamber (12a) and the third chamber (12c) of the first booster Is introduced into said second chamber (12b) of said first booster (10). 12. The method of claim 11,
In the second operating mode, the third chamber (12c, 12c ') is filled and emptied through the same line (21, 21').

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