Method and system for generating a vacuum

Abstract

Method for an engine that features: Opening a throttle upstream of an ejector coupled to an inlet manifold to increase the vacuum generation rate through the ejector during a first operating mode; and Closing the throttle upstream of the ejector to increase the vacuum generation level through the ejector during a second operating mode, wherein the opening and closing of the throttle is based on a desired vacuum level in a vacuum vessel.

Description

[0001] The present invention relates to the improvement of the efficiency of the vacuum generation of an ejector coupled to a motor system.

[0002] Vehicle systems can contain various vacuum-consuming devices that are actuated using vacuum. These can include, for example, a brake booster. The vacuum used by these devices can be supplied by a dedicated vacuum pump. In other embodiments, one or more ejectors can be coupled to the engine system, which utilize the engine airflow and use it to generate a vacuum.

[0003] From US 6 951 199 B2, a method for an engine is known which includes: opening a throttle upstream of an ejector coupled to an intake manifold to increase the vacuum generation rate by the ejector during a first operating mode; and closing the throttle upstream of the ejector to increase the vacuum generation level by the ejector during a second operating mode.

[0004] US 2011 / 0 132 311 A1 and US 2012 / 0 024 261 A1 establish further relevant prior art. The former relates to intake systems with a vacuum suction device to generate a vacuum. The latter provides systems and methods for generating a vacuum in an engine. The system comprises a first throttle upstream of a plurality of cylinders and a second throttle upstream of one of the cylinders. The system further comprises a vacuum reservoir in fluid communication with an intake port downstream of the second throttle; a vacuum consumer in fluid communication with the vacuum reservoir, the vacuum consumer being controlled by an actuator; and a pneumatic actuator driven by a pressure state of the vacuum reservoir to adjust the second throttle.

[0005] The inventors recognized that ejector configurations may no longer provide an increasing vacuum as the outlet pressure decreases. The object of the present invention is therefore to provide means and methods that at least partially enable the delivery of said vacuum as the outlet pressure decreases. This object is achieved by the features of the independent claims. Advantageous embodiments of the invention are described in the dependent claims.

[0006] The inventors further discovered that ejectors can deliver increasing vacuums even as the outlet pressure decreases, provided the pressure at the drive inlet is reduced. Thus, by throttling the drive airflow through an ejector in such a way that the ejector pressure ratio (i.e., the ejector outlet pressure relative to the drive air inlet pressure of the ejector) is maintained at or above a threshold ratio (e.g., at or above 0.71), an existing ejector can produce even deeper final vacuums, even when the source vacuum is reduced.

[0007] In one example, the above problem can be at least partially solved by a procedure for an engine that includes: closing a throttle upstream of an ejector coupled to an intake manifold to increase the level of vacuum generation by the ejector during a first operating mode; and opening the throttle to increase the vacuum generation rate by the ejector during a second operating mode. This achieves rapid vacuum evacuation at lower manifold vacuums and an even deeper vacuum in the ejector at higher manifold vacuums.

[0008] As an example, an engine system may include an ejector coupled to an intake manifold in a line coupled upstream of an intercooler, with the line running parallel to an air intake duct. A first ejector throttle may be coupled directly upstream of the ejector, without any other devices or flow couplings in between, to allow pressure reduction in the ejector. A second air intake throttle may be coupled to the intake manifold downstream of the intercooler in the air intake duct. During conditions where the intake manifold vacuum is lower, at least a portion of the intake air may flow through the ejector with the first throttle open into the line to create a vacuum for a vacuum-consuming device of the engine (such as a brake booster).By flowing air through the ejector with the first throttle more open, the high suction or pumping flow rate through the ejector can be advantageously used to quickly raise the vacuum level of the vacuum-consuming device. However, the final vacuum level achieved may not be low enough; for example, the level reached may be lower than a desired vacuum level. If the inlet manifold vacuum is higher (as during low-load conditions), the desired vacuum level can be reached by flowing air through the ejector with the first throttle opened a second time, and thus further closed. By flowing air through the ejector with the first throttle further closed, a pressure reduction upstream of the ejector can be achieved to raise the final vacuum level to the desired level, albeit with a lower pumping flow rate.Adjustments to the first throttle can be compensated for by corresponding adjustments to the second throttle to maintain airflow to the intake manifold. If the opening of the first throttle is enlarged, the opening of the second throttle can be correspondingly reduced, and vice versa.

[0009] In this way, both a high vacuum pumping rate and a deeper final vacuum can be achieved using an existing engine system ejector. By opening a throttle directly upstream of the ejector to increase upstream pressure, rapid vacuum pump-out can be achieved during lower manifold vacuums. By closing the throttle upstream of the ejector to decrease the upstream pressure, an even deeper vacuum level can then be obtained during higher manifold vacuums at a slower pumping rate. In one example, the deeper vacuum can be advantageously used to supply vacuum to a brake booster for a single brake stop with high acceleration force (e.g., a "panic stop"). Overall, the efficiency of the ejector's vacuum generation is increased without significantly increasing component costs or complexity.

[0010] It is understood that the above summary serves to present a selection of concepts in simplified form, which are further described in the subsequent detailed description. It is not intended to identify any key or essential features of the claimed subject matter, the scope of which is defined by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to embodiments that eliminate disadvantages mentioned above or in any part of this disclosure.

[0011] The subject matter of the present disclosure will be better understood by reading the following detailed description of non-restrictive embodiments with reference to the accompanying drawings, wherein: Fig. Figure 1 shows a schematic representation of a motor system comprising an ejector and a throttle coupled upstream of the ejector. Fig. 2 embodiments of the ejector with the upstream throttle in an open or a closed position. Fig. Figure 3 shows the vacuum generation in the ejector when it is throttled and when it is not throttled. Fig. Figure 4 shows a detailed flowchart illustrating a routine that can be used to control the opening of the ejector throttle to improve the efficiency of vacuum generation. Fig. Figures 5-6 show exemplary adjustments to the ejector throttle that are carried out during vacuum generation in an ejector.

[0012] Methods and systems for improving vacuum generation in an ejector equipped with a motor system such as the motor system of the Fig. 1 is coupled. A choke can be coupled directly upstream of the ejector, as in Fig. 2 shown, and a position of the throttle can be adjusted to vary the pressure upstream of the ejector ( Fig. 3) By selectively reducing the pressure upstream of the ejector, a deeper vacuum can be achieved with a lower suction rate. A control unit can be configured to perform a control routine, such as the exemplary routine of the Fig. 4. To operate the ejector in a first operating mode with the throttle open to generate a lower vacuum level more quickly, or in a second operating mode with the throttle more closed to generate a higher vacuum level more slowly. Exemplary adjustments are shown in the Fig. 5-6 described. In this way, the advantages of both a higher vacuum pump-out rate and a lower vacuum pump-out rate can be obtained. Fig. Figure 1 shows an exemplary engine system 10, which includes an engine 12. In this example, the engine 12 is a spark-ignition engine of a vehicle, wherein the engine contains a plurality of cylinders 14, each cylinder containing a piston. Combustion processes in each cylinder 14 drive the pistons, which in turn rotate the crankshaft 16, as is known to those skilled in the art. Furthermore, the engine 12 can contain a plurality of engine valves, wherein the valves are coupled to the cylinders 14 and control the inflow and outflow of gases in the plurality of cylinders 14.

[0013] The engine 12 includes an engine inlet 23 and an engine outlet 25. The engine inlet 23 contains an air inlet throttle 22, which is in fluid communication with an engine inlet manifold 24 along an inlet channel 18. Air can enter the inlet channel 18 from an air intake system (AIS) that includes an air cleaner 33 in conjunction with the vehicle's environment. The position of the throttle 22 can be varied by a control unit 50 via a signal supplied to an electric motor or actuator contained in the throttle 22, a configuration commonly referred to as electronic throttle control (ETC). In this way, the throttle 22 can be operated to vary the intake air supplied to the inlet manifold and the plurality of cylinders 14.The inlet 23 can contain a mass airflow sensor 58 (in the inlet channel 18) and a manifold air pressure sensor 60 (in the inlet manifold 24) to supply the signals MAF (mass air flow) or MAP (manifold air pressure) to the control unit 50.

[0014] The engine exhaust system 25 includes an exhaust manifold 48 leading to an exhaust port 35, which discharges exhaust gases into the atmosphere. The engine exhaust system 25 can include one or more emission control devices 70 mounted in a directly coupled position. The one or more emission control devices can include a three-way catalytic converter, a NOₓ catalyst, and a NOₓ catalyst. x -It contains a storage catalyst, a diesel particulate filter, an oxidation catalyst, etc. It is understood that other components may be included in the engine, such as a variety of valves and sensors, as discussed in more detail below.

[0015] In some embodiments, the engine system 10 is a supercharged engine system, further comprising a supercharging device. In the present example, the intake duct 18 includes a compressor 90 for supercharging an intake air charge received along the intake duct 18. An intercooler 26 is coupled downstream of the compressor 90 for cooling the supercharged air charge before it is delivered to the intake manifold. In embodiments where the supercharging device is a turbocharger, the compressor 90 can be coupled to and driven by a turbine (not shown) in the engine intake 25 of the engine system 10. Furthermore, the compressor 90 can be driven, at least partially, by an electric motor or a crankshaft 16.

[0016] An optional bypass channel 28 can be coupled across the compressor 90 to redirect at least a portion of the intake air compressed by the compressor 90 back upstream of the compressor. The amount of air redirected through the bypass channel 28 can be controlled by opening the compressor's bypass valve (CBV) 30, which is located in the bypass channel 28. By controlling the CBV 30 and varying the amount of air redirected through the bypass channel 28, the boost pressure delivered downstream of the compressor can be regulated. This enables boost control and pressure rise control.

[0017] A line 80, parallel to the air intake duct 18, can be configured to divert a portion of the intake air received by the air cleaner 33 via an ejector 160 to the intake manifold 24. The line 80 can be coupled to the air intake duct 18 at a point upstream of the charge air cooler 26 and downstream of the compressor 90. The ejector 160 can be an ejector, injector, eductor, Venturi jet pump, or a similar passive device. As further described in Fig. As implemented in Figure 2, the ejector 160 can have an upstream drive inlet through which air enters the ejector, a throat or carry inlet connected to a vacuum reservoir 38 via a first check valve 40, and a mixing-flow outlet through which air that has passed through the ejector 160 can exit and be directed towards the inlet manifold 24. The ejector outlet can be coupled to the inlet manifold via the check valve 72. The check valve 72 can allow the airflow in the inlet manifold to be retained and not flow back through the ejector 160 if the air pressure in the inlet manifold is higher than the air pressure in the line 80. When the air pressure in the intake manifold is higher, air can flow through the ejector and into line 82, from where the air can be directed back to the intake channel upstream of compressor 90.A flow direction through line 82 from downstream of the ejector to upstream of the compressor can be ensured by the check valve 74. In principle, the high-pressure point in the illustrated system (compressor outlet) can always be coupled to the ejector inlet, and the ejector outlet point is automatically routed to the lowest pressure point via the check valves. In alternative embodiments, actively controlled valves can be used instead of passive check valves if this is cost-effective. Air flowing through the drive inlet can be converted into flow energy in the ejector 160, generating a low pressure that is transmitted to the neck (or carry inlet) and draws air from the neck. The first check valve 40 allows the vacuum reservoir 38 to retain any portion of its vacuum, provided the pressures in the drive inlet of the ejector and in the vacuum reservoir are balanced.In the present example, the ejector is a device with three openings, comprising a drive inlet, a mixed-flow outlet, and a throat / carrying inlet. However, in alternative embodiments of the intake, a check valve such as the check valve 40 can be integrated into the ejector.

[0018] The vacuum reservoir 38 can also receive a vacuum directly from the intake manifold 24. A second check valve 68 allows the vacuum reservoir 38 to retain any portion of its vacuum if the pressure in the intake manifold 24 and the vacuum reservoir is balanced. The check valve 68 is referred to as a bypass path, providing a high-flow air path from the supercharger to the intake manifold. This flow path prevails when the supercharger pressure is higher than the manifold pressure. The vacuum reservoir 38 can be coupled to a vacuum consumption device 39 of the engine. For example, the vacuum consumption device 39 can be a brake booster coupled to the vehicle's wheel brakes, with the vacuum reservoir 38 being a vacuum cavity downstream of a diaphragm in the brake booster.The vacuum reservoir 38 can be an internal vacuum reservoir configured to amplify the force supplied by a driver 15 via a brake pedal 154 to actuate the vehicle's wheel brakes (not shown). The position of the brake pedal 154 can be monitored by a brake pedal sensor 152. In an alternative example, the vacuum reservoir can be a low-pressure storage tank contained within a fuel vapor purge system.

[0019] Line 80 can further include a throttle 150 that is directly coupled upstream of the ejector 160. In particular, the throttle 150 can be coupled to the ejector 160 without any flow devices or couplings between the ejector and the throttle. As used here, the throttle 150 coupled to the ejector 160 in line 80 can be a first throttle (here also referred to as the ejector throttle), while the throttle 22 coupled to the intake manifold 24 in the air intake duct can be a second throttle (here also referred to as the air intake throttle). In this way, the engine system 10 can include a first throttle coupled to the intake manifold upstream of the charge air cooler 26 and a second throttle coupled to the intake manifold downstream of the charge air cooler 26.

[0020] As with reference to the Fig. As detailed in 2-4, the control unit 50 can be configured to adjust the opening of the first throttle 150 to vary the pressure in an upstream region of the ejector, thereby influencing the suction flow rate in the ejector as well as the final vacuum achieved in the ejector. Specifically, the control unit can position the first throttle in a first position where it is more open (e.g., fully open or further open) to increase the pressure upstream of the ejector, thereby increasing the suction flow rate and enabling an increase in the vacuum pump-off rate in the ejector. For example, the first throttle 150 can be moved to the first, more open position during conditions where the manifold vacuum is lower (e.g., during turbocharged engine operation).By allowing air to flow through the ejector 160 with the first throttle 150 further opened, the high suction or pumping flow rate through the ejector can advantageously be used to rapidly increase the vacuum level of the vacuum reservoir 38, so that a sufficient vacuum is available for use by the vacuum consumption device 39. However, the final vacuum level achieved may not be low enough (e.g., the vacuum level may be lower than a desired vacuum level).

[0021] In another example, the control unit 50 can move the first throttle 150 to a second, different position where it is less open (e.g., fully closed or further closed compared to the first position) to reduce the pressure upstream of the ejector. This reduces the suction flow rate and allows the vacuum level drawn from the ejector to increase more slowly. For example, the first throttle 150 can be moved to the second, more closed position during conditions where the manifold vacuum is higher (e.g., during naturally aspirated engine operation).By allowing air to flow through the ejector 160 with the first throttle 150 less open, the lower final vacuum level achieved by the ejector can advantageously be used to increase the vacuum level of the vacuum vessel 38 to the desired level, although the increase may be slower than if the vacuum in the ejector is generated with the first throttle in the first, wider open position.

[0022] Adjustments to the first throttle 150 can be compensated for by corresponding adjustments to the second throttle 22. By making these adjustments, the airflow to the engine intake manifold is maintained at a desired level. For example, in response to an increase in the opening of the first throttle (e.g., when the first throttle is moved to the first, wider open position), the opening of the second throttle can be correspondingly reduced (e.g., the second throttle can be moved to a more closed position). Likewise, in response to a decrease in the opening of the first throttle (e.g., when the first throttle is moved to the second, less open position), the opening of the second throttle can be correspondingly increased (e.g., the second throttle can be moved to a more open position).

[0023] The engine system 10 may also include a control system 46, which contains a control unit 50, sensors 51, and actuators 52. Example sensors include an engine speed sensor 54, an engine coolant temperature sensor 56, an air mass sensor 58, and an exhaust manifold pressure sensor 60. Example actuators include engine valves, the CBV 30, a first ejector throttle 150, and a second air intake throttle 22. The control unit 50 may further include physical memory containing instructions, programs, and / or code for operating the engine. An example routine executed by the control unit 50 is shown in Fig. 4 shown.

[0024] In this way, the system delivers Fig. 1. An engine system capable of closing a throttle upstream of an ejector coupled to an intake manifold to increase the level of vacuum generated by the ejector during a first operating mode. Then, during a second operating mode, the system is capable of opening the throttle to further increase the rate of vacuum generation by the ejector. Here, the throttle can be more closed during the first operating mode and then less closed during the second. In other words, the throttle can be less open during the first operating mode and then more open during the second operating mode.

[0025] Now, with reference to Fig. 2 an embodiment of the inlet ejector of the Fig. Figure 1 shows the first choke coupled upstream of it. In particular, it shows Fig. Figure 2 in Figure 200 describes an embodiment of the ejector which is operated with the upstream ejector throttle open, and Figure 250 describes an embodiment of the ejector which is operated with the throttle closed. It is understood that previously in Fig. 1 presented components in Fig. 2 bear the same reference numbers and are not presented again.

[0026] The ejector 160 can receive a driving flow in an upstream region 202 of the ejector. The upstream region corresponds to a section of the ejector located upstream of the ejector neck 204. After passing through the neck 204, a mixed flow can flow into a downstream region 206 of the ejector, i.e., a region located downstream of the ejector neck. Due to the constricted section at the ejector neck, the velocity of the air flowing through the ejector can increase at the neck (relative to the velocity of the air in the upstream or downstream region), and the pressure of the airflow can decrease accordingly (relative to the pressure of the air in the upstream or downstream region) due to a Venturi effect (also known as the Bernoulli effect). In principle, the driving velocities in the neck remain in the sound range, while the velocity increases.If the flow rate is sufficient, sound pressure levels develop in the throat. Downstream of the throat, the velocities can be supersonic (as in a Laval nozzle). The pressure drop from the throat can be extracted as a vacuum and is also known as suction flow. The velocity at the throat therefore determines not only the suction flow rate but also the final vacuum achieved. As used here, the final vacuum refers to the vacuum achieved at zero suction flow rate.

[0027] The inventors recognized that the velocity in the neck, and consequently the suction flow rate and the final vacuum, can vary based on the pressure differential across the neck of the ejector. In particular, by preventing the pressure ratio from falling below a threshold ratio (for example, below an empirically determined ratio of 0.71), the performance of the ejector can be optimized under all conditions. In itself, throttling increases the pressure ratio of the ejector. By changing the pressure in an upstream region of the ejector, the properties of the vacuum generated in the ejector can thus be modified.In particular, a throttle 150, which is positioned directly upstream of the ejector without a flow device or flow coupling between the ejector and the throttle, can advantageously be used to vary the pressure in the upstream region of the ejector and thereby provide a desired final vacuum or suction flow rate.

[0028] As in Fig. As described in Figure 1, the upstream throttle 150 and the ejector 160 can be coupled to the intake manifold in a line parallel to an air intake duct, the line being coupled to the air intake duct upstream of an intercooler. During conditions where the manifold vacuum is lower (such as moderate charging conditions), at least some of the intake air can be directed into the line, where the air flows through the ejector with the throttle open to a first, larger extent (or in a first, more open position) to generate a vacuum for a vacuum-consuming device of the engine (such as a brake booster). By allowing air to flow through the ejector with the first throttle more open, the high suction or pumping flow rate through the ejector is advantageously used to rapidly raise the vacuum level of the vacuum-consuming device to a first level.

[0029] Fig. Figure 2 shows the throttle in a first position, open to a first (larger) degree. Here, if the throttle 150 is opened further (e.g., fully open, as shown), the pressure in the upstream section 202 of the ejector (on both sides of the throttle 150) can be ~100 kPa, while the pressure in the downstream section 206 of the ejector can be ~30 kPa. That is, there can be no pressure difference across the throttle 150 in the upstream section, while the pressure difference across the ejector throat 204 is higher (here ~70 kPa). This higher pressure difference across the throat leads to a higher velocity of the driving airflow across the throat, and consequently to a higher suction flow rate. However, the final vacuum achieved can be lower. For example, the final vacuum achieved can be ~65 kPa.

[0030] In principle, this initial level of achieved final vacuum can be lower than a desired vacuum level. Therefore, to achieve the desired vacuum level under conditions where the manifold vacuum is higher (such as during non-charging conditions), air can flow into the line and through the ejector with the throttle open (or in a second position) by a second amount less than the first. Here, the second position can be one in which the throttle is more closed than when it is in the first position. By allowing air to flow through the ejector with the throttle more closed, the pressure upstream of the ejector can be reduced to raise the final vacuum level to the desired level, albeit at a lower suction flow rate.

[0031] Fig. Figure 2 shows the throttle in a second position, opened by a second (smaller) amount. Here, the throttle opening is reduced (e.g., fully closed, as shown, or partially closed). If the throttle is closed further, the pressure in the upstream section 202 of the ejector, upstream of the throttle, can be ~100 kPa, while the pressure in the upstream section 202 of the ejector, downstream of the throttle, can be ~70 kPa. That is, by adjusting the throttle position, the pressure in the upstream section of the ejector is reduced by ~30 kPa. This pressure drop leads to a decrease in the drive flow velocity across the throat and a reduced pressure differential across the throat. In the example shown, the ejector section directly upstream of the throat can be at ~70 kPa, while the pressure in the downstream section of the ejector can be ~30 kPa.This means there can be a lower pressure differential across the ejector throat (here ~40 kPa) compared to when the throttle is wider open in the first position. This lower pressure differential across the throat results in a lower pressure drop in the throat and consequently a lower suction flow rate. However, the final vacuum level can be higher. For example, the final vacuum level can be 80 kPa. By moving the throttle from the first wider open position (at position 200) to the second wider closed position (at position 250), the final vacuum is increased from a lower initial level to a higher second level. In this way, throttling the ejector reduces the pressure upstream of the ejector, reduces the suction flow rate across the intake throat, but allows for a lower vacuum level to be achieved.

[0032] It goes without saying that, while the example of the Fig. 2. The displacement of the throttle from a first position (in 200), in which it is fully open, to a second position (in 250), in which it is fully closed, is not to be understood as a limitation. In alternative embodiments, the throttle can be moved from a first position, in which it is further open, to a second position, in which it is further closed, in order to achieve the desired pressure reduction and a deeper final vacuum. Furthermore, the throttle position can be continuously controlled to any position between a fully open and a fully closed position. In particular, the throttle position can be continuously varied to prevent the pressure ratio from falling below a threshold pressure ratio (e.g., below 0.71).

[0033] The Fig. the Fig. Figure 3 illustrates this effect graphically. In particular, the Fig. The suction capacity for increasing manifold vacuum levels is shown. The group of lines 302 (solid lines) represents the suction capacity when the suction is operated at full throttle (i.e., with an upstream pressure of up to 100 kPa). Specifically, this group of lines 302 represents the suction capacity when the suction is at full throttle at manifold pressures of 10, 15, 20, 25, 30, 40, and 50 kPa, respectively (from left to right). The group of lines 304 (dashed lines) represents the suction capacity when the suction is operated at a throttle (i.e., with an upstream pressure of up to 70 kPa). Specifically, this group of lines 304 represents the suction capacity with the suction at a throttle at manifold pressures of 50 and 55 kPa, respectively (from left to right).

[0034] Upon closer examination, it is found that the lines converge at a threshold pressure ratio, in this case a pressure ratio of 0.71 (at or around 70 kPa). Therefore, a control operation can be performed when the pressure ratio in the ejector approaches the threshold pressure ratio of 0.71. Specifically, when the pressure ratio approaches 0.71, the ejector inlet can be throttled to prevent the pressure ratio from falling below 0.71 (i.e., to maintain the pressure ratio at or above the threshold pressure ratio of 0.71). In this way, the ejector performance is always optimized for both suction flow and vacuum.

[0035] The system also delivers unexpected, serendipitous, and synergistic benefits. The throttled airflow reduces the drive airflow and thus the bypass flow around the throttle plate. Consequently, even higher manifold vacuums can be achieved when the airflow around the throttle plate is reduced. This, in turn, increases the manifold vacuum. This is because the flow through an acoustic nozzle depends on the density upstream of that nozzle. The converging cone of the ejector acts like an acoustic nozzle. The maximum flow through this nozzle is typically reached at a pressure ratio of 0.9, where the drive flow becomes an acoustic flow.

[0036] For example, if the ejector is operated without throttle (i.e., with the throttle more open), the rate of the suction flow drawn off at the throat is higher (i.e., a steeper slope is observed), while the final vacuum achieved is lower (e.g., ~65 kPa). Conversely, if the ejector is operated with throttle (i.e., with the throttle more closed), the rate of the suction flow drawn off at the throat is lower (i.e., a shallower slope is observed), while the final vacuum achieved is higher (e.g., ~80 kPa).

[0037] As seen here in Fig. As explained in more detail in section 4, a control unit can, for a first period, operate the ejector without throttle opening to a larger initial amount, in order to quickly raise the vacuum level to a lower initial level. Subsequently, for a second period, the control unit can operate the ejector with throttle opening to a smaller initial amount, in order to slowly raise the vacuum level from the lower initial level to a higher initial level. In this way, the advantages of both higher and lower vacuum pumping can be achieved with an existing ejector in a cost-effective and simple manner.

[0038] In itself, a deeper vacuum can offer several advantages. For example, if the ejector is configured to supply a vacuum to a brake booster, the booster can use that vacuum for high G-forces, such as single braking stops from high vehicle speed. While a deep vacuum may have limited use for rapid brake vacuum recovery, the vacuum from the brake booster can be used to bring the vehicle to a halt in the event of a panic stop.

[0039] Now, referring to Fig. Figure 4 shows method 400 for controlling the operation of a throttle coupled upstream of an intake manifold ejector. The method is used to improve the efficiency of the ejector's vacuum generation.

[0040] In 402, the procedure includes the estimation and / or measurement of engine operating conditions. These may include, for example, engine speed, engine temperature, vehicle speed, environmental conditions (barometric pressure, ambient temperature and humidity), catalyst temperature, vacuum levels in vacuum reservoirs coupled with vacuum consumption devices of the engine (or vacuum actuators), etc.

[0041] In section 404, based on the estimated engine operating conditions, a desired vacuum level can be set in a vacuum reservoir coupled to a vacuum-consuming device of the engine. The vacuum in the reservoir can be used to actuate the vacuum-consuming device. In one example, the vacuum-consuming device is a brake booster coupled to the vehicle's wheel brakes. The control unit can set a vacuum level required for the brake booster to operate. The desired vacuum level can be based on, for example, a vehicle speed. As the vehicle speed increases, the desired vacuum level can increase so that the brake booster can stop the vehicle when the driver applies the brake pedal while the vehicle is traveling at high speeds.In alternative examples, the vacuum consumption device can be an alternative vacuum actuator such as a speed control actuator, HVAC door, etc.

[0042] In 406, it can be determined whether the difference between the current vacuum level of the vacuum-consuming device and the desired vacuum level of the vacuum-consuming device exceeds a threshold. For example, it can be determined whether the difference between the current vacuum level in the brake booster and the desired vacuum level in the brake booster is greater than the threshold. The current vacuum level of the vacuum-consuming device can be any level of vacuum currently available in a vacuum reservoir connected to the vacuum-consuming device. The threshold can be based on a vacuum level that can be generated with a continuously open (ejector) throttle.

[0043] If the distance to the desired vacuum level is greater than the threshold, the procedure in 408 includes opening the ejector throttle (or enlarging an opening of the ejector throttle) to increase pressure in the upstream portion of the ejector and allow intake air to flow through the ejector. The vacuum can then be drawn from the throat of the ejector. Opening the ejector throttle involves fully opening the ejector throttle or enlarging an opening of the ejector throttle from the current degree of opening of the throttle. For example, the throttle can be moved from a current setting to a first position in which the throttle is more open. By adjusting the throttle upstream of the ejector to a larger opening, a velocity of the driving flow in the throat of the ejector can be increased, which increases the suction flow rate. Thus, the vacuum can be raised rapidly, albeit to a lower final vacuum level.

[0044] In 410, the procedure includes adjusting the opening of an air intake throttle based on the opening of the ejector throttle. As previously explained in more detail, the ejector can be coupled to the intake manifold in a duct parallel to an air intake duct, with the duct being coupled to the air intake duct upstream of an intercooler. The throttle upstream of the ejector can be a first throttle positioned in the duct directly upstream of the ejector without a flow device or coupling between the ejector and the first throttle. The engine can further include a second throttle coupled to the intake manifold in the air intake duct downstream of the intercooler. The control unit can adjust the setting of the second throttle based on the first throttle. In particular, in 410, the opening of the second throttle can be reduced in response to the opening of the first throttle.For example, if the first throttle is moved to a more open position, the second throttle can be moved to a more closed position to allow the maintenance of a clean engine airflow.

[0045] As more air exits the ejector, the main throttle closes, achieving the engine's target airflow. The ejector flow rate tends to remain essentially constant, even when the intake flow rate varies. In other words, the intake flow tends to displace the intake flow rate rather than adding to it. Thus, for constant conditions at both the intake inlet and the ejector outlet, the exhaust flow rate remains essentially constant, even with varying intake flow rates.

[0046] In 412, it can be confirmed that a vacuum limit of the ejector has been reached with the ejector throttle further opened. That is, it can be determined whether the ejector has reached the final vacuum achievable with the first throttle position. While the ejector can reach this final vacuum level quickly due to the larger throttle opening, the final vacuum level may be lower than the desired vacuum level. To achieve the desired, lower vacuum level, the method described in 414 includes closing the ejector throttle (or reducing an opening in the throttle) to decrease the pressure in the upstream region of the ejector and the flow of inlet air through the ejector. The vacuum can then be drawn from the neck of the ejector. Closing the ejector throttle involves either completely closing the ejector throttle or reducing an opening in the ejector throttle.For example, the throttle can be moved from a first position, where it was more open (or less closed), to a second position, where it is more closed (or less open). By adjusting the throttle upstream of the ejector to close more tightly, the velocity of the driving flow in the ejector throat can be reduced, which decreases the suction flow rate but increases the final vacuum achieved. In this way, the vacuum can be gradually increased to an even deeper final vacuum.

[0047] In 418, the procedure includes adjusting the opening of an air intake throttle based on the opening of the ejector throttle. As previously explained in more detail, the control unit can adjust the setting of the second throttle coupled in the air intake duct based on the first throttle coupled upstream of the ejector. In particular, in 418, the opening of the second throttle can be increased in response to the closing of the first throttle. For example, if the first throttle is moved to a more closed position, the second throttle can be moved to a more open position to maintain a clean engine airflow.

[0048] If a greater amount of vacuum generation is required in this way, the motor can be operated in either of two modes: a first mode of vacuum generation in which a throttle upstream of an ejector is moved to a more open position to increase the rate of vacuum generation through the ejector, and a second mode of vacuum generation in which the throttle is moved to a more closed position to increase the level of vacuum generation through the ejector.

[0049] Again in 406, if the distance from the desired vacuum level is less than the threshold, it can be determined in 407 whether the manifold vacuum is higher than a threshold vacuum. For example, the manifold vacuum may be higher than a threshold vacuum during unsuppressed engine operation. If the manifold vacuum is higher than the threshold vacuum, and the distance to the desired vacuum level is less than a threshold (that is, the vacuum level of the vacuum-consuming device is already high enough), the routine goes directly to 414 to provide the lower vacuum. That is, the desired vacuum level is reached by closing the throttle (e.g., by moving the throttle to the second, more closed position) to achieve the lower vacuum more slowly.Here, the engine is only operated in the second operating mode to achieve the desired vacuum level with a slower suction flow rate when the desired vacuum level is lower than a threshold, and when an intake manifold vacuum is higher than a threshold level.

[0050] If the distance from the desired vacuum level is lower than the threshold (in 406), and the intake manifold vacuum is lower than the threshold vacuum (in 407), the routine proceeds directly to 408 to quickly deliver the desired vacuum. For example, during supercharged engine operation, the manifold vacuum may be lower than the threshold vacuum. This means the desired vacuum level is achieved by opening the throttle (e.g., moving the throttle to the first, wider-open position) to reach the desired vacuum more quickly. Here, the engine can only be operated in the first operating mode to achieve the desired vacuum level with a faster suction flow rate if the desired vacuum level is lower than a threshold and if the intake manifold vacuum is lower than a threshold level.

[0051] In this way, if a smaller amount of vacuum generation is required, the engine can be operated in one of two modes based on the manifold vacuum level. By operating in the first vacuum generation mode with the throttle upstream of the ejector in the more open position when the manifold vacuum is lower, the desired vacuum level can be reached quickly. By operating in the second vacuum generation mode with the throttle upstream of the ejector in the more closed position when the manifold vacuum is higher, the desired vacuum level can be reached even though the manifold vacuum is high, albeit with slower vacuum generation. By adjusting the opening of a second throttle, coupled to the intake manifold downstream of the intercooler, based on the first throttle during either of the first and second operating modes, airflow to the engine can be maintained.

[0052] In typical ejector operation, the drive inlet of an ejector is subjected to high pressure (e.g., compressor outlet), and the air is discharged at low pressure (e.g., intake manifold pressure). While this works above a threshold pressure ratio, as soon as the pressure ratio (as determined by the MAP / TIP ratio) falls below the threshold (e.g., below 0.71), the ejector's effectiveness decreases. By reducing the pressure at the ejector's drive inlet such that the pressure ratio does not fall below 0.71, lower suction vacuums can be achieved, even while reducing the throttle bypass flow (i.e., the drive air flow rate).

[0053] Now in Fig. 5 represents the Fig. This represents the generation of a vacuum in an ejector coupled to an engine intake manifold in a vehicle system. Fig. This further illustrates exemplary adjustments of a throttle positioned directly upstream of the ejector, which are carried out while the flow is being directed through the ejector, in order to vary a vacuum pump-out rate as well as a final vacuum level achieved in the ejector. Fig. Graph 502 depicts changes in the ejector throttle position. Graph 504 shows changes in the vacuum level in a container coupled to a vacuum consumption device of the engine, and Graph 506 shows changes in vehicle speed. All graphs are graphical representations of time along the x-axis.

[0054] In the present example, the ejector is configured to supply vacuum to a brake booster. Before t1, the vehicle can travel at a lower initial speed (graphic 506). Due to the lower vehicle speed, the required vacuum level 503 in the brake booster can be lower. This reduced vacuum requirement can be met by operating the engine with the ejector throttle more open (e.g., fully open, as shown in graphic 502) (graphic 504).

[0055] For example, the lower vacuum requirement can be met by operating the engine in a first operating mode with the ejector throttle open. In this mode, air flows through an ejector positioned in a duct coupled to the engine's intake manifold, with the duct running parallel to the engine's air intake port. As air flows through the ejector, a throttle located in the duct directly upstream of the ejector can be adjusted to a more open position to increase pressure in an upstream section of the ejector (i.e., upstream of an ejector throat). Increasing the pressure in this upstream section increases the suction flow rate in the ejector, allowing the desired vacuum level to be reached quickly.

[0056] At t1, the vehicle speed can increase to a second, higher speed (graphical representation 506). Due to the increase in vehicle speed, the desired vacuum level 503 can correspondingly increase from the higher vehicle speed to a higher level, anticipating the need for a greater braking force to decelerate the vehicle. However, the required higher vacuum level may not be achieved by operating the engine with the ejector throttle more open, since the final vacuum achievable with the open ejector throttle may be lower than the desired vacuum level. Thus, at t2, the desired vacuum level can be achieved by operating the engine in a second operating mode with the ejector throttle closed (e.g., fully closed as shown in graphical representation 502) (graphical representation 504).Air can flow through the ejector, which is positioned in the line coupled to the engine intake manifold, while the throttle, located directly upstream of the ejector in the line, is moved from a more open position (before t1) to a more closed position (after t1) to reduce the pressure in the upstream section of the ejector. Reducing the pressure upstream decreases the suction flow rate in the ejector, but increases the final vacuum level achievable in the ejector, allowing the desired vacuum level to be reached by t2. At t2, the ejector throttle can be opened once the desired vacuum level is reached.

[0057] In this way, the motor operates in a first operating mode (before t1) with the ejector throttle more open to reduce the vacuum faster (but to a lower level), and then in a second operating mode (after t1) with the ejector throttle more closed to reduce the vacuum to a higher level (but more slowly). In one example, the motor is operated only in the first operating mode to achieve a desired vacuum level if the desired vacuum level is lower than a threshold. In another example, the motor is operated only in the second operating mode to achieve the desired vacuum level if the desired vacuum level is lower than a threshold and while an intake manifold vacuum is higher than a threshold level (e.g., if the manifold vacuum is high and the brake booster vacuum is high).

[0058] In other examples, the motor can be operated in either of the first or second operating modes to achieve the desired vacuum level, as in the example of the Fig. This is explained in more detail in section 6. Over a given motor cycle, the motor is operated with both a wider open throttle and a wider closed throttle to achieve faster and deeper vacuum reduction. In one example, the motor is operated in each of the first and second operating modes to reach a desired vacuum level if the desired vacuum level is higher than a threshold.

[0059] The Fig. the Fig. Figure 6 illustrates changes in an ejector throttle position in graphical representation 602. In the example of the Fig. 6. The ejector is configured to deliver a vacuum to a brake booster. Fig.Graph 604 represents a brake booster vacuum level in conjunction with a desired (or threshold) vacuum level 603. The application of the brake pedal is shown in graph 606. All graphs are graphical representations of time along the x-axis.

[0060] At t0, the vacuum level available in the brake booster may be sufficiently high, for example, at or directly below a desired vacuum level 603. This may be because sufficient vacuum was previously generated in the ejector and stored in a vacuum reservoir coupled to the brake booster. Consequently, at t0, the motor can be operated with an airflow through the ejector, while an ejector throttle directly coupled upstream of the ejector is held in a more closed position (graphical representation 602).

[0061] Between t0 and t1, the driver can depress the brake pedal several times (graphical representation 606). Each time the brake pedal is depressed, vacuum can be consumed by the brake booster, and the vacuum level in the brake booster can drop (graphical representation 604). At t1, the vacuum level in the brake booster can be substantially low. For example, the difference between the existing vacuum level and the desired vacuum level 603 can exceed a threshold value. This higher vacuum requirement cannot be supplied by the ejector in time while the throttle is closed.

[0062] Accordingly, at t1, the motor is operated in a first operating mode, with the ejector throttle set in a position where it is more open (relative to the throttle opening before t1). Because the throttle is more open, the air pressure upstream of the ejector neck can be increased. Intake air can then flow through the ejector neck at a higher velocity, creating a vacuum with a higher suction rate. This allows the brake booster vacuum level to rise rapidly between t1 and t2. In other words, a faster vacuum reduction is achieved between t1 and t2 when the motor is operated in the first operating mode.

[0063] While the first operating mode with the wider throttle opening allows for faster vacuum reduction, the final vacuum achieved may not be sufficiently high. For example, at t2, the ejector may reach a vacuum limit below the desired vacuum level 603. If the motor were then operated in the first mode after t2 (as shown by the dashed line 601), the final vacuum achieved would fluctuate below the desired vacuum level (as shown by the dashed line 605).

[0064] To achieve the desired vacuum, the motor is switched to a second operating mode at t2, in which the ejector throttle is set to a position where it is less open (relative to the throttle opening in the first operating mode, between t1 and t2). Because the throttle is less open, the air pressure upstream of the ejector throat can be reduced. Intake air can then flow through the ejector throat at a lower velocity, creating a deeper vacuum at a lower suction rate. This allows the brake booster vacuum level to slowly increase to the desired vacuum level of 603 after t2. In other words, a deeper vacuum reduction at a slower vacuum reduction rate is achieved after t2 when the motor is operated in the second operating mode.Thus, a control unit can generate a vacuum in an ejector coupled to an intake manifold at a first higher rate and to a first, lower vacuum level by enlarging an opening of a throttle coupled upstream of the ejector; and then increase the vacuum in the ejector from the first, lower level to a second, higher level at a second, lower rate by reducing the opening of the throttle.

[0065] By inserting a throttle valve upstream of a system ejector, a simple and cost-effective approach to improving the ejector's vacuum generation performance is provided. Opening the throttle valve directly upstream of the ejector increases the vacuum release rate, enabling faster vacuum release during lower manifold vacuum conditions. Closing the throttle valve during high manifold vacuum conditions increases the level of vacuum release, allowing for deeper vacuum pumping at a slower pumping rate. This effectively provides the benefits of achieving a higher vacuum pumping rate and a deeper final vacuum level using an existing engine system ejector. Overall, the ejector's vacuum generation performance is improved.

[0066] It should be noted that the exemplary control routines included here can be used with various engine and / or vehicle system configurations. The specific routines described here can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. In principle, various illustrated actions, processes, or functions can be performed in parallel within the illustrated sequence or, in some cases, omitted. Likewise, the processing sequence is not strictly necessary to obtain the features and benefits of the exemplary implementations described here but is provided for easier illustration and description. One or more of the illustrated actions or functions can be performed repeatedly, depending on the specific strategy used.Furthermore, the described actions can graphically represent a code that is to be programmed into the computer-readable storage medium in the engine control system.

[0067] It is understood that the configurations and routines disclosed herein are exemplary and that these specific embodiments are not to be understood as limiting, since many variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, four-cylinder boxer engines, and other engine types. Furthermore, one or more of the various system configurations can be used in combination with one or more of the described diagnostic routines. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and / or properties disclosed herein.

Claims

[1] Method for an engine which has: Opening a throttle upstream of an ejector coupled to an inlet manifold to increase the vacuum generation rate through the ejector during a first operating mode; and Closing the throttle upstream of the ejector to increase the vacuum generation level through the ejector during a second operating mode, wherein the opening and closing of the throttle is based on a desired vacuum level in a vacuum vessel. [2] Method according to claim 1, wherein the motor is operated only in the first operating mode to achieve the desired vacuum level when the desired vacuum level is lower than a threshold, and wherein the motor is operated in each of the first and second operating modes to achieve the desired vacuum level when the desired vacuum level is higher than the threshold. [3] Method according to claim 2, wherein the threshold is based on a vacuum level that can be generated during a running throttle opening. [4] Method according to claim 2, wherein the generated vacuum stored in the vacuum reservoir is used to actuate a vacuum consumption device of the engine, wherein the ejector comprises a drive current inlet connected to the vacuum reservoir, and wherein the desired vacuum level is based on a vehicle speed. [5] Method according to claim 3, wherein the motor is operated only in the second operating mode to achieve the desired vacuum level when the desired vacuum level is lower than the threshold, and when an inlet manifold vacuum is higher than a threshold level. [6] Method according to claim 1, wherein the ejector is coupled to the inlet manifold in a line parallel to an air intake duct, wherein the line is coupled to the air intake duct upstream of an intercooler, and wherein the throttle upstream of the ejector is a first throttle positioned in the line directly upstream of the ejector, without a flow device or coupling between the ejector and the first throttle. [7] Method according to claim 6, further comprising, during each of the first and second operating modes, the adjustment of an opening of a second throttle coupled to the intake manifold downstream of the charge air cooler based on the first throttle. [8] Method according to claim 7, wherein the adjustment during operation in the second operating mode includes increasing the opening of the second throttle in response to the closing of the first throttle; and during operation in the first operating mode includes decreasing the opening of the second throttle in response to an opening of the first throttle. [9] Method for an engine which has: Generating a vacuum in an ejector coupled to an inlet manifold at a first, higher rate, and to a first, lower vacuum level by enlarging an opening of a throttle coupled upstream of the ejector; and Increasing the vacuum in the ejector from the first level to a second, higher vacuum level at a second, lower rate, by reducing the opening of the throttle based on a desired vacuum level in a vacuum reservoir coupled to a vacuum consumption device of the engine. [10] Method according to claim 9, wherein reducing the opening of the throttle includes completely closing the throttle. [11] Method according to claim 9, wherein the generation of a vacuum by opening the throttle and the increase of the vacuum by closing the throttle are carried out in response to the desired vacuum level being at or higher than the second level. [12] Method according to claim 10, wherein the generated vacuum is stored in the vacuum container and wherein the desired vacuum level is based on a vehicle speed. [13] Method according to claim 9, wherein the throttle is a first throttle, and wherein both the ejector and the first throttle are coupled to the inlet manifold upstream of an intercooler. [14] Method according to claim 13, further comprising the adaptation of an opening of a second throttle coupled to the intake manifold downstream of the charge air cooler based on the opening of the first throttle. [15] Method according to claim 14, wherein the adjustment when increasing the opening of the first throttle includes decreasing the opening of the second throttle and when decreasing the opening of the first throttle includes increasing the opening of the second throttle. [16] Vehicle system that features: an engine containing an intake manifold; a compressor coupled with an intercooler; a vacuum consumption device; an ejector coupled to the intake manifold upstream of the charge air cooler; a first throttle coupled upstream of the ejector; and a control unit with instructions to If a vacuum level in both the intake manifold and the vacuum consumption device is higher than a threshold, the first throttle will close to reduce pressure upstream of the ejector. [17] System according to claim 16, wherein closing the first throttle to reduce the pressure upstream of the ejector includes generating a vacuum in the ejector and increasing the vacuum level of the vacuum consumption device at a first, slower rate. [18] System according to claim 17, further comprising a second throttle coupled to the intake manifold downstream of the charge air cooler, wherein the control unit further includes instructions to enlarge an opening of the second throttle in response to the closing of the first throttle. [19] System according to claim 18, wherein the control unit further contains instructions to open the first throttle in order to increase the vacuum level of the vacuum consumption device at a second, faster rate; and to reduce the opening of the second throttle in response to an opening of the first throttle. [20] System according to claim 16, wherein the vacuum consumption device is a brake booster coupled to vehicle wheel brakes. [21] System according to claim 16, wherein the first throttle is pneumatically operated, and wherein the closing of the first throttle includes the at least partial closing of the first throttle in response to a pressure ratio of the ejector that falls to or below a threshold ratio.

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