Successive turbocharged engine crankcase pressure control device, engine and method

Abstract

This invention relates to a crankcase pressure control device, engine, and method for turbocharged engines, belonging to the field of engine technology. It solves the defects of existing crankcase control devices, such as long vacuum pump operating time and susceptibility to damage. The invention includes an oil-gas separator, with its outlet connected in parallel to a first branch and a second branch. A first electric valve is installed on the first branch, and a second electric valve and a vacuum pump are connected in series on the second branch. The first electric valve, the second electric valve, and the vacuum pump are connected to a controller to operate under its control. The control device and method of this invention shorten the vacuum pump's operating time, resulting in better vacuum pump reliability.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and more specifically to a crankcase pressure control device, engine, and method for a turbocharged engine. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] In a sequentially turbocharged engine, multiple turbochargers will work in sequence according to different operating conditions. For non-operating turbochargers, if the crankcase pressure is high, the return oil from the turbocharger to the crankcase will not be smooth due to the pressure, which may cause the turbocharger to leak oil.

[0004] Currently, in crankcase pressure control devices, such as Figure 1 As shown, the inlet of the oil-gas separator 1 is connected to the crankcase 2, and the outlet of the oil-gas separator 1 is directly connected to the vacuum pump 3. The vacuum pump 3 is connected to the air filter 4 or directly connected to the external atmospheric environment. The vacuum pump 3 is connected to the motor 5, and its operation is controlled by the motor 5. The crankcase pressure requirement is set, and the crankcase pressure is monitored by the pressure sensor 6. When the pressure is higher than the set pressure, the ECU 7 controls the vacuum pump 3 to start continuously pumping air. The vacuum pump 3 works continuously to keep the pressure within the set range.

[0005] The existing technology has the following technical defects:

[0006] 1. When a turbocharger is not working, the pressure in the crankcase is high due to the resistance of the vacuum pump itself (about 2 kPa). This is especially true for open-type breathing systems (where the oil and gas in the crankcase are directly vented to the atmosphere after separation). This causes the vacuum pump to start at a low load and run for a long time.

[0007] 2. The vacuum pump controller needs to be set to adjustable speed, and the speed of the vacuum pump needs to be calibrated in advance according to the engine speed. The calibration process is complicated, has poor adaptability to actual working conditions, and the vacuum pump speed changes frequently during engine operation, making it very easy to be damaged.

[0008] 3. Directly controlling the start-up process of the vacuum pump by the crankcase pressure in a closed loop means that the vacuum pump needs to be on almost continuously. This is especially problematic for open-loop breathing systems (where the oil and gas in the crankcase are directly vented to the atmosphere after separation), which can easily damage the vacuum pump. Summary of the Invention

[0009] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a crankcase pressure control device for a turbocharged engine, which overcomes the defects of existing crankcase pressure control devices.

[0010] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0011] In a first aspect, embodiments of the present invention provide a crankcase pressure control device for a turbocharged engine, including an oil-gas separator. The outlet end of the oil-gas separator is connected to a first branch and a second branch arranged in parallel. A first electric valve is installed on the first branch. A second electric valve and a vacuum pump are connected in series on the second branch. The first electric valve, the second electric valve, and the vacuum pump are connected to a controller to operate under the control of the controller.

[0012] Optionally, an air filter can be connected after the ends of the first and second branches merge.

[0013] Optionally, the controller is an ECU.

[0014] Secondly, embodiments of the present invention provide a turbocharged engine, which is equipped with the turbocharged engine crankcase pressure control device described in the first aspect, and an oil-gas separator is connected to the crankcase.

[0015] Thirdly, embodiments of the present invention provide a method for operating the crankcase pressure control device for a sequentially turbocharged engine described in the first aspect:

[0016] When only one or two turbochargers are working after the engine starts: if the crankcase pressure is not greater than the set value, the first electric valve opens, the second electric valve closes, and the vacuum pump does not work; if the crankcase pressure is greater than the set value, the first electric valve closes, the second electric valve opens, and the vacuum pump works simultaneously.

[0017] When the engine is running: if it is determined that not all turbochargers are working, the first electric valve remains closed, the second electric valve remains open, and the vacuum pump works simultaneously; if it is determined that all turbochargers are working, the second electric valve closes and the vacuum pump stops working.

[0018] Optionally, the first electric valve opens when all boosters are in operation.

[0019] Optionally, the setting value is 1.5kPa-2.5kPa, preferably 2kPa.

[0020] Optionally, the crankcase pressure value can be obtained based on the engine speed and engine load parameters, or based on a crankcase pressure sensor.

[0021] Optionally, engine load parameters include engine power and torque.

[0022] Optionally, the vacuum pump operates at a constant speed during operation.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. The pressure control device and method of the present invention, through the parallel connection of a first branch and a second branch, as well as a first electric valve and a second electric valve after the oil-gas separator, realizes the bypass function of the vacuum pump. After the engine starts, the first branch has the function of reducing the crankcase pressure. The vacuum pump is only turned on when the crankcase pressure is greater than the set value. The vacuum pump works according to the turbocharger engagement and the crankcase pressure. The vacuum pump will not be turned on continuously, avoiding the problem of high crankcase pressure caused by the high self-resistance of the conventional vacuum pump directly connected in series with the oil-gas separator, which leads to premature start-up, long running time, and easy damage.

[0025] 2. The pressure control device and method of the present invention allow the vacuum pump to operate at a constant speed, without frequent changes due to engine speed variations, making the operation more reliable. Furthermore, the calibration process is simpler, and it has strong adaptability to actual working conditions. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0027] Figure 1 This is a schematic diagram of the existing crankcase pressure control device.

[0028] Figure 2 This is a schematic diagram of the crankcase pressure control device according to Embodiment 1 of the present invention;

[0029] Figure 3 This is a schematic diagram of the working process of the pressure control device in Embodiment 3 of the present invention;

[0030] Among them, 1. oil-gas separator, 2. crankcase, 3. vacuum pump, 4. air filter, 5. motor, 6. pressure sensor, 7. ECU, 8. first branch, 9. second branch, 10. first electric valve, 11. second electric valve. Detailed Implementation

[0031] In this embodiment, a sequential turbocharger engine refers to an engine that uses multiple turbochargers. The multiple turbochargers will engage in operation in sequence according to different operating conditions. At low load, one or more turbochargers will not work, while at high load, all turbochargers will be engaged.

[0032] Example 1

[0033] This embodiment provides a crankcase pressure control device for a sequentially turbocharged engine, such as... Figure 2As shown, it includes an oil-gas separator 1 for connection with crankcase 2. The inlet end of the oil-gas separator 1 is used for connection with crankcase 2. Existing equipment can be used for the oil-gas separator 1, and its specific structure will not be described in detail here. The outlet end of the oil-gas separator 1 is connected to a first branch 8 and a second branch 9 arranged in parallel. The ends of the first branch 8 and the second branch 9 that are connected to the outlet end of the oil-gas separator 1 are the beginning ends, and the other ends are the end ends.

[0034] The ends of the first branch 8 and the second branch 9 converge and are connected to the air filter 4, or the ends of the first branch 8 and the second branch 9 converge and are directly connected to the external atmospheric environment.

[0035] The first branch 8 is equipped with a first electric valve 10, which can be an electric ball valve or an electric butterfly valve, etc., and can be configured according to actual needs by those skilled in the art.

[0036] The second branch 6 is connected in series with a second electric valve 11 and a vacuum pump 3. The second electric valve 11 is located close to the oil-gas separator 1. The second electric valve 11 is an electric ball valve or an electric butterfly valve, etc., which can be set according to actual needs by those skilled in the art.

[0037] The first electric valve 10, the second electric valve 11, and the vacuum pump 3 are all connected to the controller, which controls their operation. In this embodiment, the controller can be ECU7, and there is no need to set up an additional controller. ECU7 is connected to the first electric valve 10, the second electric valve 11, and the vacuum pump 3, and can control the operation of the first electric valve 10, the second electric valve 11, and the vacuum pump 3.

[0038] Example 2:

[0039] This embodiment provides a turbocharged engine equipped with the crankcase pressure control device described in Embodiment 1. The inlet end of the oil-gas separator 1 is connected to the crankcase 2, using existing connection methods, which will not be described in detail here. A pressure sensor is installed inside the crankcase 2 and is connected to an ECU 7. The pressure sensor can collect gas pressure information from the crankcase 2 and transmit it to the ECU 7. The ECU 7 is also connected to a speed sensor on the engine output shaft, which can receive the collected speed information. The ECU 7 can record the engine load parameters, including the engine power and torque. The above technology can be achieved using existing technology and will not be described in detail here.

[0040] The other components of the engine can be the same as those of existing turbocharged engines, and will not be described in further detail here.

[0041] Example 3

[0042] This embodiment provides a method for controlling crankcase pressure in a sequentially turbocharged engine as described in Embodiment 1:

[0043] like Figure 3 As shown, after the engine is started, ECU7 is powered on, and ECU7 controls the first electric valve 10 of the first branch 8 to open and the second electric valve 11 to close, and the vacuum pump 3 does not work.

[0044] As the engine runs, after starting, when one or both turbochargers are engaged, the activation conditions of the vacuum pump are determined based on the pressure in crankcase 2 or the engine speed and load parameters. The load parameters are the engine's power and torque.

[0045] Specifically, when the pressure in crankcase 2 is not greater than the set value, it is determined that the conditions for vacuum pump 3 to be turned on have not been met. ECU7 controls the first electric valve 10 to remain open, the second electric valve 11 to remain closed, and vacuum pump 3 does not work.

[0046] As the engine runs, when the pressure in crankcase 2 is detected to be greater than the set value, it is determined that the vacuum pump 3 has met the conditions for opening. ECU7 controls the first electric valve 10 to close and the second electric valve 11 to open. ECU7 controls the vacuum pump 3 to start, and the vacuum pump 3 starts to pump air. The vacuum pump 3 works at a constant speed, so that the crankcase pressure is kept below the set value.

[0047] In this embodiment, the set value is 1.5kPa-2.5kPa, preferably 2kPa. According to experiments, when the crankcase pressure is less than 2kPa, the turbocharger will not leak oil.

[0048] In this embodiment, since the engine speed and load parameters are in correspondence with the crankcase pressure, and this correspondence can be obtained in advance, and since the engine speed and load parameters are routinely recorded by the ECU, the crankcase pressure can be directly obtained using a crankcase pressure sensor or by using the engine speed and load parameters. The engine load parameters refer to the engine power and torque, which the ECU can routinely record, and then determine the pressure inside the crankcase.

[0049] As the engine load gradually increases during operation, multiple turbochargers are put into operation sequentially. As the engine runs and the load increases, a third and more turbochargers are put into operation in sequence. At this time, ECU7 judges the status of turbocharger operation. When it is determined that not all turbochargers are in operation, that is, at least one turbocharger is not in operation, ECU7 controls the first electric valve 10 to remain closed and the second electric valve 11 to remain open. Vacuum pump 3 continues to operate at a constant speed, so that the pressure in crankcase 2 is maintained below the set value. When ECU7 determines that all turbochargers are in operation, since all turbochargers are in operation, there will be no oil leakage due to high crankcase pressure. Therefore, ECU7 controls the first electric valve 10 to open, controls the second electric valve 11 to close, and controls vacuum pump 3 to stop working.

[0050] The pressure control method in this embodiment achieves the bypass function of vacuum pump 3 by setting the first branch 8, the first electric valve 10, and the second electric valve 11. Traditional crankcase pressure control devices are prone to high crankcase pressure due to their high resistance. Therefore, after the engine starts, the vacuum pump is likely to start working, resulting in premature start-up and long running time. This embodiment overcomes this defect by using the bypass function of vacuum pump 3. Vacuum pump 3 only starts working after one or two turbochargers are engaged and the crankcase pressure is greater than the set value, avoiding premature start-up of vacuum pump 3, shortening the running time of vacuum pump 3, avoiding the problem of easy damage to vacuum pump 3, and increasing the reliability of vacuum pump 3 itself. Moreover, in this embodiment, vacuum pump 3 operates at a constant speed, which does not change frequently with the engine speed, making its operation more reliable.

[0051] In this embodiment, the vacuum pump is activated when the ECU detects that the engine speed has reached the activation threshold (e.g., 1000 r / min) or the engine load parameter has reached the set threshold, thus achieving open-loop control. Traditional vacuum pump control methods are closed-loop: when the vacuum pump is activated, the ECU detects the crankcase pressure and calculates the difference between this value and the average of the upper and lower thresholds of the crankcase pressure to obtain the crankcase pressure deviation value. This deviation value is then used to obtain the required vacuum pump speed through PID control and output to the vacuum pump to control its speed and keep the crankcase pressure within the upper and lower threshold range. This application uses open-loop control, which simplifies the calibration process and improves applicability to actual operating conditions.

[0052] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A crankcase pressure control device for a turbocharged engine, including an oil-gas separator, characterized in that, The outlet end of the oil-gas separator is connected to a first branch and a second branch arranged in parallel. The first branch is equipped with a first electric valve, and the second branch is connected in series with a second electric valve and a vacuum pump. The first electric valve, the second electric valve and the vacuum pump are connected to the controller to operate under the control of the controller. The turbocharged engine uses multiple turbochargers. When it is determined that not all turbochargers are working, the first electric valve remains closed and the second electric valve remains open, while the vacuum pump operates. When it is determined that all turbochargers are working, the first electric valve opens, the second electric valve closes, and the vacuum pump stops working. The vacuum pump operates at a constant speed.

2. The crankcase pressure control device for a turbocharged engine as described in claim 1, characterized in that, The air filter is connected after the first and second branches merge at their ends.

3. The crankcase pressure control device for a turbocharged engine as described in claim 1, characterized in that, The controller is an ECU.

4. A turbocharged engine, comprising a crankcase pressure control device as described in any one of claims 1-3, wherein an oil-gas separator is connected to the crankcase.

5. A method for controlling crankcase pressure in a turbocharged engine according to any one of claims 1-3, characterized in that: When only one or two turbochargers are working after the engine starts: if the crankcase pressure is not greater than the set value, the first electric valve opens, the second electric valve closes, and the vacuum pump does not work; if the crankcase pressure is greater than the set value, the first electric valve closes, the second electric valve opens, and the vacuum pump works simultaneously. When the engine is running, if it is determined that not all turbochargers are working, the first electric valve remains closed and the second electric valve remains open, while the vacuum pump operates; when it is determined that all turbochargers are working, the second electric valve closes and the vacuum pump stops operating. The vacuum pump operates at a constant speed.

6. The method of the crankcase pressure control device for a turbocharged engine as described in claim 5, wherein the set value is 1.5 kPa-2.5 kPa, preferably 2 kPa.

7. The method of the crankcase pressure control device for a turbocharged engine as described in claim 5, wherein the crankcase pressure value is obtained based on the engine speed and engine load parameters or based on a crankcase pressure sensor.

8. The method of the crankcase pressure control device for a turbocharged engine as described in claim 7, wherein the engine load parameters include the engine power and torque.

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