Negative pressure generation mechanism

Abstract

The present invention provides a negative pressure generation mechanism that can minimize the loss of boost pressure in the supercharging region. [Solution] The system comprises an engine 2, a vacuum bag 3 whose interior is kept in a negative pressure state, an intake passage 5 connected to the intake manifold 4 of the engine 2 and equipped with a compressor 6, intercooler 7, and throttle valve 8 of a supercharger 1, a first passage 9 connecting the downstream side of the throttle valve 8 in the intake passage 5 to the vacuum bag 3, a second passage 11 connecting the downstream side of the intercooler 7 in the first passage 9 or the intake passage 5 to the upstream side of the compressor 6 in the intake passage 5, an ejector pump 12 provided in the second passage 11, a third passage 15 connecting the first passage 9 or the vacuum bag 3 to the ejector pump 12, and a first valve 13 provided in the second passage 11, wherein the opening and closing operation of the first valve 13 is performed according to the negative pressure state of the vacuum bag 3.

Description

Technical Field

[0001] This invention relates to a negative pressure generating mechanism.

Background Art

[0002] Among the components that make up the brakes of vehicles such as hybrid vehicles (HV), plug-in hybrid vehicles (PHEV) capable of external charging and external power supply, and gasoline engine vehicles, there is a brake booster (force multiplying device) for reducing the driver's braking operation force. This brake booster generates a high braking force by assisting the force acting on the rod of the cylinder so as to synchronize with the driver's braking operation by the pressure difference between the negative pressure back (master back) in a negative pressure state and the atmospheric pressure.

[0003] As a method of putting the negative pressure back in a negative pressure state, for example, there is a method using a negative pressure pump such as the electric vacuum pump 20 shown in Patent Document 1 below (see particularly paragraph 0025, FIG. 1, etc. of the cited document 1), but there is a problem of causing an increase in component costs and the like. Even without this negative pressure pump, when the engine is in the natural intake region, the inside of the intake manifold becomes a negative pressure state, so the negative pressure back can be put in a negative pressure state with that negative pressure. However, when the engine is in the supercharging region, the inside of the intake manifold becomes a positive pressure state, so there is a problem that the negative pressure back cannot be put in a negative pressure state and the supercharging region has to be temporarily interrupted and changed to the natural intake region.

[0004] To solve this problem, for example, in Patent Document 2 below, a configuration is proposed in which the downstream side (high pressure side) of the throttle valve 440 in the intake passage 400 and the upstream side (low pressure side) of the compressor impeller 220 are connected by a positive pressure introduction passage 710 and a reflux passage 730. A diffuser 720 is provided between the positive pressure introduction passage 710 and the reflux passage 730. A negative pressure is generated by the flow passing through the diffuser 720 from the high pressure side to the low pressure side, and this negative pressure puts the brake booster 300 in a negative pressure state.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2016-160854 [Patent Document 2] Japanese Patent Publication No. 2018-171955 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In the configuration shown in Patent Document 2, regardless of the negative pressure state of the brake booster 300, a portion of the supercharged intake air is recirculated to the upstream side of the compressor impeller 220, resulting in a problem of constant supercharge pressure loss.

[0007] Therefore, the objective of this invention is to provide a negative pressure generation mechanism that can minimize the loss of boost pressure in the supercharging region. [Means for solving the problem]

[0008] In order to solve the above problems, this invention provides: The engine and A negative pressure back system maintains a negative pressure state inside, An intake passage connected to the intake manifold of the aforementioned engine, and equipped with a supercharger compressor, intercooler, and throttle valve, A first passage connecting the downstream side of the throttle valve in the intake passage to the negative pressure back, A second passage connecting the first passage or the downstream side of the intake passage from the intercooler to the upstream side of the intake passage from the compressor, An ejector pump provided in the second passage, A third passage connecting the first passage or the negative pressure back and the ejector pump, The first valve provided in the second passage, A negative pressure generating mechanism (first configuration) is configured such that the opening and closing operation of the first valve is performed according to the negative pressure state of the negative pressure back.

[0009] In the first configuration, The first passage may be provided with a capture unit for capturing foreign matter in the intake passage (second configuration).

[0010] In the second configuration, The second passage can be configured to be connected between the negative pressure back of the first passage and the capture unit (third configuration).

[0011] In the first configuration, The second passage is connected to the upstream side of the throttle valve in the intake passage, and when the engine is in the supercharging region and the negative pressure in the negative pressure back is insufficient, the opening of the throttle valve is reduced while supercharging is performed by the supercharger, and the first valve is opened (fourth configuration).

[0012] In the first configuration, A second valve is provided between the ejector pump in the second passage and the connection point upstream of the compressor in the intake passage, A bypass passage that connects the second valve and the first passage while bypassing the negative pressure back, A connecting passage that connects the first passage and the second passage, A capture unit provided in the second passage, The present invention further comprises the following: the second passage branches off from the intake passage upstream of the throttle valve; the first valve is provided at the connection between the second passage and the connecting passage; and both the first and second valves are three-way valves. During the cleaning mode of the ejector pump, the first valve is switched to allow flow in the second passage and the connecting passage, while the second valve is switched to block the flow in each of the passages passing through the second valve, During the cleaning mode of the capturing unit, the first valve is switched to allow the flow from the intake passage through the second passage toward the ejector pump, and the second valve is switched to allow the flow from the ejector pump through the second passage toward the bypass passage (Configuration 5).

[0013] In Configuration 5, the cleaning mode can be configured (Configuration 6) to be performed during the idling of the engine.

Advantages of the Invention

[0014] In this invention, a first valve is provided in a second passage connecting the downstream side of the intercooler in the first passage or the intake passage and the upstream side of the compressor in the intake passage, and the opening and closing operation of the first valve is configured to be performed according to the negative pressure state of the negative pressure back. Therefore, when the negative pressure state of the negative pressure back is ensured in the supercharging region, the loss of the supercharging pressure can be suppressed by closing the first valve.

Brief Description of the Drawings

[0015] [Figure 1] It is a block diagram showing a first embodiment of a negative pressure generating mechanism according to this invention. [Figure 2] It is a block diagram showing the pressure state during full-open running in the natural intake region in the negative pressure generating mechanism according to the first embodiment. [Figure 3] It is a block diagram showing a state where a sufficient negative pressure state of the negative pressure back is ensured in the negative pressure generating mechanism according to the first embodiment. [Figure 4A] It is a schematic diagram showing the action of the first valve (an example) when the negative pressure state of the negative pressure back in the negative pressure generating mechanism according to the first embodiment is not sufficient. [Figure 4B] It is a schematic diagram showing the action of the first valve (an example) when a sufficient negative pressure state of the negative pressure back in the negative pressure generating mechanism according to the first embodiment is obtained. [Figure 5] It is a block diagram showing a second embodiment of a negative pressure generating mechanism according to this invention. [Figure 6A] This is a schematic diagram showing the state in which foreign matter has been captured in the capture unit in the negative pressure generation mechanism according to the second embodiment. [Figure 6B] This is a schematic diagram showing the state in which foreign matter has been released from the capture unit in the negative pressure generation mechanism according to the second embodiment. [Figure 7] This is a block diagram showing a third embodiment of the negative pressure generation mechanism according to the present invention. [Figure 8A] This is a schematic diagram showing the state of the first and second valves when the negative pressure state of the negative pressure back is insufficient in the supercharging region of the negative pressure generation mechanism according to the third embodiment. [Figure 8B] This is a schematic diagram showing the state of the first and second valves when a sufficient negative pressure state for negative pressure back is obtained in the supercharging region of the negative pressure generation mechanism according to the third embodiment. [Figure 8C] This is a schematic diagram showing the state of the first and second valves when cleaning (removal of foreign matter) is being performed on the ejector pump of the negative pressure generation mechanism according to the third embodiment. [Figure 8D] This is a schematic diagram showing the state of the first and second valves when cleaning (scavenging) the capture section of the negative pressure generation mechanism according to the third embodiment. [Modes for carrying out the invention]

[0016] A first embodiment of the negative pressure generating mechanism according to this invention will be described based on the drawings. This negative pressure generating mechanism can be applied to vehicles such as hybrid vehicles (HV), plug-in hybrid vehicles (PHEV) capable of external charging and external power supply, and gasoline engine vehicles, which have an engine 2 equipped with a supercharger 1 and a negative pressure back 3 that assists the driver's braking force by creating a negative pressure state inside the engine and using the pressure difference between the negative pressure and atmospheric pressure.

[0017] As shown in Figure 1, an intake passage 5 for drawing fresh air into the engine 2 is connected to the intake manifold 4 of the engine 2. The compressor 6, intercooler 7, and throttle valve 8 of the supercharger 1 are arranged in order from upstream to downstream in the intake passage 5.

[0018] In the negative pressure generation mechanism A of the first embodiment, the downstream side of the throttle valve 8 in the intake passage 5 and the negative pressure back 3 are connected by a first passage 9. The first passage 9 is provided with a check valve 10 that allows only unidirectional flow from the negative pressure back 3 toward the intake manifold 4.

[0019] The downstream side of the intercooler 7 and the upstream side of the throttle valve 8 in the intake passage 5 is connected to the upstream side of the compressor 6 in the intake passage 5 by a second passage 11. An ejector pump 12 is provided in the second passage 11. The ejector pump 12 has a needle with a partially narrowed flow path cross-sectional area. A negative pressure is created around the needle by the intake air ejected from the nozzle at the tip of the needle. A first valve 13 is provided on the upstream side of the ejector pump 12 in the second passage 11, and a second valve 14 is provided on the downstream side. The first valve 13 is a gate valve, and the second valve 14 is a check valve that allows only unidirectional flow from the downstream side of the intercooler 7 to the upstream side of the compressor 6 through the second passage 11.

[0020] The negative pressure bag 3 and the ejector pump 12 are connected by a third passage 15. The third passage 15 is equipped with a check valve 16 that allows only unidirectional flow from the negative pressure bag 3 to the ejector pump 12.

[0021] An exhaust manifold 17 of engine 2 is connected to an exhaust passage 18 for sending exhaust gases outside the vehicle. The turbine 19 of supercharger 1 is located in the exhaust passage 18. The exhaust passage 18 is also provided with a bypass passage 20 that bypasses the turbine 19, and a wastegate valve 21 is located in the bypass passage 20. When the wastegate valve 21 is open, the exhaust gas is mainly discharged through the bypass passage 20. On the other hand, when the wastegate valve 21 is closed, the exhaust gas is sent to the turbine 19 of supercharger 1, and the exhaust pressure causes the turbine 19 and a compressor 6 mounted coaxially with it to rotate. The rotation of the compressor 6 then supercharges the intake air.

[0022] The operation of the negative pressure generation mechanism A according to the first embodiment will now be described.

[0023] (1) When engine 2 is in the naturally aspirated range In the naturally aspirated region, the pressure inside the intake manifold 4 is negative relative to atmospheric pressure. As a result, as indicated by the white arrows in each passage in Figure 1, intake air flows from the first passage 9 to the intake passage 5, and the negative pressure bag 3 becomes negative. At this time, the first valve 13 is closed to prevent intake air from unnecessarily returning to the downstream side of the intercooler 7 through the second passage 11.

[0024] (2) When engine 2 is in the supercharged range In the supercharging region, the pressure inside the intake manifold 4 is positive relative to atmospheric pressure. Therefore, as in the naturally aspirated region, it is not possible to create a negative pressure state inside the negative pressure bag 3. To address this, as shown by the black arrows in each passage in Figure 1, the first valve 13 is opened, and the high-pressure intake air downstream of the compressor 6, generated by supercharging, is returned to the upstream side of the compressor 6 via the second passage 11. The negative pressure created when the intake air passes through the ejector pump 12 creates a negative pressure state inside the negative pressure bag 3.

[0025] (3) When engine 2 is in the naturally aspirated range (fully open) In the fully open state in the naturally aspirated range, the pressure inside the intake manifold 4 may become positive relative to atmospheric pressure. In this case, as in (2) above, it is not possible to create a negative pressure state inside the negative pressure bag 3.

[0026] Therefore, with the first valve 13 in the open position, the opening of the fully open throttle valve 8 is slightly reduced to cause a pressure loss in the intake air passing through the throttle valve 8, and the resulting decrease in intake air volume is compensated for by supercharging by the supercharger 1. An example of the pressure in each passage 5, 11 and the intake manifold 4 at this time is shown in Figure 2. In this way, by controlling the first valve 13, the throttle valve 8 and the supercharger 1, it is possible to maintain the driver's request for full throttle while creating a negative pressure state in the negative pressure bag 3, as explained in (2) above, by intentionally creating a pressure difference between the downstream side of the intercooler 7 and the upstream side of the compressor 6.

[0027] (4) When the negative pressure back 3 is in a sufficiently negative pressure state in the supercharging region In the supercharging region, as described in (2) above, intake air is recirculated from the downstream side of the intercooler 7 to the upstream side of the compressor 6, but this recirculation causes a loss of boost pressure. Therefore, when the negative pressure state of the negative pressure bag 3 is sufficient, the first valve 13 is closed to prevent intake air from the intake passage 5 from recirculating to the second passage 11, as shown in Figure 3, thereby preventing a decrease in boost pressure.

[0028] As an example of this first valve 13, the configuration shown in Figures 4A and 4B can be adopted. This first valve 13 has a valve body 22 with a through hole that can communicate with the second passage 11, a valve chamber 23 in which the valve body 22 is housed and connected to the negative pressure bag 3, and an elastic spring 24 that biases the valve body 22 housed in the valve chamber 23 toward the opening direction. When the negative pressure state of the negative pressure bag 3 is insufficient, the valve body 22 opens due to the biasing force of the elastic spring 24, and intake air recirculates through the second passage 11. On the other hand, when the negative pressure state of the negative pressure bag 3 is sufficient, the valve body 22 is drawn up against the biasing force of the elastic spring 24 by the negative pressure, closing the valve and preventing the recirculation of intake air through the second passage 11.

[0029] The negative pressure generating mechanism A according to the first embodiment can create a negative pressure state inside the negative pressure bag 3 regardless of whether the engine 2 is in the naturally aspirated region (1), the supercharged region (2), or the fully open state of the naturally aspirated region (3). Furthermore, since the opening and closing operation of the first valve 13 is performed according to the negative pressure state of the negative pressure bag 3, when the negative pressure bag 3 is in a sufficiently negative pressure state in the supercharged region (4), the loss of supercharge pressure can be suppressed as much as possible.

[0030] Figure 5 shows a second embodiment of the negative pressure generation mechanism according to this invention. The negative pressure generation mechanism B according to the second embodiment shares the same basic configuration as the negative pressure generation mechanism A according to the first embodiment, but differs in that a capture unit 25 is provided in the first passage 9, the second passage 11 is connected between the negative pressure back 3 of the first passage 9 and the capture unit 25, and the third passage 15 is connected to the first passage 9 instead of the negative pressure back 3.

[0031] The capture unit 25 is provided to prevent foreign matter F (see Figure 6A, etc.) in the intake passage 5, such as condensed water generated in the intercooler 7, oil mist from blow-by gas, and exhaust particles from the low-pressure exhaust gas recirculation device, from entering the second passage 11. For example, a mesh filter or a catch tank can be used. The operation in the naturally aspirated and supercharged regions is basically the same as the operation of the negative pressure generation mechanism A according to the first embodiment.

[0032] In the negative pressure generation mechanism B according to the second embodiment, as shown in Figure 6A, when intake air flows through the second passage 11 in the supercharging region, foreign matter F such as condensed water, oil mist, and exhaust particles contained in the intake air is captured by the capture unit 25. On the other hand, as shown in Figure 6B, when the intake manifold 4 is in a negative pressure state in the naturally aspirated region, the foreign matter F captured by the capture unit 25 is sucked in by the negative pressure and sent to the intake manifold 4.

[0033] In the second embodiment, the negative pressure generating mechanism B captures foreign matter F in the intake passage 5 with the capture unit 25, preventing the foreign matter F from reaching the check valve 10 or the second passage 11. This prevents the foreign matter F from clogging the ejector pump 12 and hindering negative pressure formation in the supercharging region. Furthermore, since the negative pressure generated in the intake manifold 4 in the natural intake region allows for the suction and removal of the foreign matter F, the maintenance effort required for the ejector pump 12 can be reduced.

[0034] Figure 7 shows a third embodiment of the negative pressure generation mechanism according to this invention. The negative pressure generation mechanism C according to the third embodiment has the same basic configuration as the negative pressure generation mechanism A according to the first embodiment, but differs in that both the first valve 13 and the second valve 14 are three-way valves, it further has a bypass passage 26 that connects the second valve 14 and the first passage 9 while bypassing the negative pressure back 3, and a connecting passage 27 that connects the first passage 9 and the second passage 11, and a capture part 25 is provided on the intake passage 5 side of the second passage 11 from the first valve 13. A check valve 28 is provided on the intake passage 5 side of the connecting passage 27 of the first passage 9 to prevent backflow from the intake manifold 4 to the bypass passage 26.

[0035] The specifications of the three-way valves used as the first valve 13 and the second valve 14 can be determined as appropriate, but it is preferable to use valves with a switching angle of 90 degrees in order to switch between the negative pressure generation state (as in (2) below) and the negative pressure-free state (as in (3) below) in the supercharging region in the shortest possible time.

[0036] The operation of the negative pressure generation mechanism C according to the third embodiment will now be described.

[0037] (1) When engine 2 is in the naturally aspirated range As shown by the white arrows within the passage in Figure 7, the negative pressure inside the intake manifold 4 causes intake air to flow from the first passage 9 to the intake passage 5, creating a negative pressure state inside the negative pressure bag 3.

[0038] (2) When engine 2 is in the supercharged range As shown by the black arrows in the passages in Figures 7 and 8A, the first valve 13 is switched to allow flow through the second passage 11 toward the ejector pump 12, and the second valve 14 is switched to allow flow from the ejector pump 12 toward the upstream side of the compressor 6 in the intake passage 5. Due to this switching, the high-pressure intake air downstream of the compressor 6, generated by supercharging, returns to the upstream side of the compressor 6 via the second passage 11, and the negative pressure generated when the intake air passes through the ejector pump 12 creates a negative pressure state inside the negative pressure bag 3.

[0039] (3) When the negative pressure back 3 is in a sufficiently negative state in the supercharging region As shown in Figure 8B, the first valve 13 is switched to block the flow through each passage via the first valve 13, and the second valve 14 is switched to block the flow through each passage via the second valve 14, thereby preventing the intake air flowing through the intake passage 5 from recirculating through the second passage 11, and thus preventing a decrease in boost pressure due to recirculation.

[0040] (4) Cleaning mode of ejector pump 12 (removal of foreign matter) As shown in Figure 8C, the first valve 13 is switched to allow airflow through the second passage 11 and the connecting passage 27 to the first passage 9, while the second valve 14 is switched to block the airflow through each passage. Then, the negative pressure in the intake manifold 4 sucks out and removes foreign matter F that causes clogging of the ejector pump 12 needle. The sucked-out foreign matter F is sent to the intake manifold 4 through the second passage 11, the connecting passage 27, the first passage 9, and the intake passage 5. This cleaning mode for the ejector pump 12 is most effective when performed while the engine 2 is idling, when the negative pressure in the intake manifold 4 is high.

[0041] (5) Cleaning mode of the capture unit 25 (sweeping of the capture unit 25) As shown in Figure 8D, the first valve 13 is switched to allow air to flow from the intake passage 5 through the second passage 11 to the ejector pump 12, and the second valve 14 is switched to allow air to flow from the ejector pump 12 through the second passage 11 to the bypass passage 26. Then, foreign matter F such as drain and water vapor captured by the capture unit 25 is discharged to the intake passage 5 (intake manifold 4) via the bypass passage 26. In this cleaning mode, the amount of intake air sent to the intake manifold 4 increases, but it is also possible to control the intake air volume to remain constant by lowering the opening of the throttle valve 8. This cleaning mode of the capture unit 25 is most effective when performed while the engine 2 is idling, when the negative pressure state of the intake manifold 4 is high.

[0042] In this cleaning mode, when intake air is injected from the nozzle at the tip of the needle of the ejector pump 12, the adiabatic expansion of the injected intake air may cause the temperature around the nozzle to drop, resulting in condensation. By moving this condensation by scavenging with negative pressure and drawing it into the intake manifold 4, a clogging prevention effect equivalent to wet cleaning can be obtained.

[0043] In the third embodiment, the negative pressure generating mechanism C has three-way valves for both the first valve 13 and the second valve 14, and is provided with a bypass passage 26 and a connecting passage 27. This allows the negative pressure state to be maintained inside the negative pressure bag 3 regardless of whether the engine 2 is in the naturally aspirated or supercharged range. Furthermore, since the opening and closing operations of the first valve 13 and the second valve 14 are performed according to the negative pressure state of the negative pressure bag 3, the loss of supercharger pressure in the supercharged range can be minimized. In addition, by switching between the first valve 13 and the second valve 14, the ejector pump 12 and the capture unit 25 can be cleaned by the negative pressure in the intake manifold 4, thereby reducing the maintenance effort required for these components.

[0044] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Accordingly, the scope of the invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0045] 1. Supercharger 2 engines 3. Vacuum back 4. Intake Manifold 5. Intake passage 6 Compressors 7 Intercooler 8. Throttle valve 9 First aisle 10 Check valve 11 Second aisle 12 Ejector pumps 13 First valve 14 Second valve 15 Third aisle 16. Check valve 17 Exhaust Manifold 18 Exhaust passage 19 Turbine 20 Detour passage 21 Wastegate Valve 22 Valve body 23 valve chambers 24 Elastic springs 25. Supplementary section 26 Bypass passage 27 Connecting passage 28 Check valve A, B, C Negative pressure generation mechanism F Foreign object

Claims

1. The engine and A negative pressure back system maintains a negative pressure state inside, An intake passage connected to the intake manifold of the aforementioned engine, and equipped with a supercharger compressor, intercooler, and throttle valve, A first passage connecting the downstream side of the throttle valve in the intake passage to the negative pressure back, A second passage connecting the first passage or the downstream side of the intake passage from the intercooler to the upstream side of the intake passage from the compressor, An ejector pump provided in the second passage, A third passage connecting the first passage or the negative pressure back and the ejector pump, The first valve provided in the second passage, A negative pressure generating mechanism having such that the opening and closing operation of the first valve is performed according to the negative pressure state of the negative pressure back.

2. The negative pressure generating mechanism according to claim 1, wherein the first passage is provided with a capture unit for capturing foreign matter in the intake passage.

3. The negative pressure generating mechanism according to claim 2, wherein the second passage is connected between the negative pressure back of the first passage and the capture unit.

4. The second passage is connected to the upstream side of the throttle valve in the intake passage. The negative pressure generating mechanism according to claim 1, wherein, when the engine is in the supercharging region and the negative pressure of the negative pressure back is insufficient, the opening of the throttle valve is reduced while supercharging is performed by the supercharger, and the first valve is opened.

5. A second valve is provided between the ejector pump in the second passage and the connection point upstream of the compressor in the intake passage, A bypass passage that connects the second valve and the first passage while bypassing the negative pressure back, A connecting passage that connects the first passage and the second passage, A capture unit provided in the second passage, The present invention further comprises the following: the second passage branches off from the intake passage upstream of the throttle valve; the first valve is provided at the connection between the second passage and the connecting passage; and both the first and second valves are three-way valves. During the cleaning mode of the ejector pump, the first valve is switched to allow flow in the second passage and the connecting passage, while the second valve is switched to block the flow in each of the passages passing through the second valve, The negative pressure generating mechanism according to claim 1, wherein during the cleaning mode of the capture unit, the first valve is switched to allow flow from the intake passage through the second passage toward the ejector pump, and the second valve is switched to allow flow from the ejector pump through the second passage toward the bypass passage.

6. The negative pressure generating mechanism according to claim 5, configured such that the cleaning mode is performed while the engine is idling.

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