Gas engine heat pump

Abstract

The present invention relates to a gas engine heat pump comprising: an engine that combusts a mixture of air and fuel; a first charger that compresses the mixture and supplies it to the engine; a first exhaust passage connected to the engine through which exhaust gas discharged from the engine flows; and a second charger driven by exhaust gas branching from the first exhaust passage to a second exhaust passage, which compresses the exhaust gas discharged from the engine and supplies it to the engine. Accordingly, it has the effect of reducing the emission of nitrogen oxides by recirculating exhaust gas without consuming separate power.

Description

Technology Field

[0001] The present invention relates to a gas engine heat pump, and more specifically, to a gas engine heat pump for reducing nitrogen oxides. Background Technology

[0002] Generally, a heat pump refers to a device that cools or heats an indoor space through the compression, condensation, expansion, and evaporation processes of a refrigerant. When cooling an indoor space, the indoor heat exchanger functions as an evaporator through which low-temperature, low-pressure refrigerant passes, while the outdoor heat exchanger functions as a condenser through which high-temperature, high-pressure refrigerant passes. Conversely, when heating an indoor space, the indoor heat exchanger functions as a condenser, and the outdoor heat exchanger functions as an evaporator.

[0003] Heat pumps can be broadly classified into electric heat pumps (EHP), which drive a compressor using an electric motor, and gas engine heat pumps (GHP), which drive a compressor using the combustion energy of fuel gas.

[0004] The above gas engine heat pump includes an engine that generates power using a mixture of fuel and air (hereinafter referred to as a mixture). For example, the engine may include an engine cylinder to which the mixture is supplied, and a piston provided to be movable within the cylinder.

[0005] The above gas engine heat pump may include an air supply device for supplying air and fuel, a fuel supply device, and a mixer for mixing the air and fuel.

[0006] The air supply device may include an air filter for purifying air. Additionally, the fuel supply device may include a zero governor for supplying fuel at a constant pressure. The air passing through the air filter and the fuel discharged from the zero governor may be mixed in the mixer (mixer) and supplied to the engine.

[0007] Meanwhile, the mixture that has passed through the above mixer can be supplied to the above engine after undergoing supercharging action by a supercharger. Representative examples of the above supercharger include a supercharger and a turbocharger.

[0008] The mixture introduced into the engine through the supercharger is supplied to each of the plurality of engine cylinders formed in the engine by passing through the intake manifold. Then, inside the plurality of engine cylinders, the mixture undergoes a combustion reaction, and the thermal energy generated by the combustion reaction is converted into mechanical energy to drive the compressor.

[0009] The exhaust gas generated by the combustion reaction of the mixture in the above engine can pass through the exhaust manifold, then pass through the exhaust gas heat exchanger and be cooled by the coolant, and then pass through the muffler to be discharged to the outside of the gas engine heat pump.

[0010] At this time, various harmful substances are generated during the combustion of fuel and air under high-temperature conditions, and there is a problem in that these are emitted to the outside along with the aforementioned exhaust gas. Representative of these harmful substances are nitrogen oxides (NOx). x ), Tetrahydrocannabinol (THC), Methane (CH4), Carbon monoxide (CO), Sulfur oxides (SO₄) x There are ), soot (PM), hydrocarbons (HC), etc.

[0011] The above-mentioned harmful substances cause various problems, including environmental pollution, when released externally, and various studies are being conducted to reduce them. Related prior art, Korean Registered Patent Publication No. 10-2007048, discloses a device for recirculating the exhaust gas into an engine to reduce exhaust gas emissions.

[0012] However, in the case of the aforementioned conventional technology, there is a problem of increased power consumption because a separate device (supercharger) that continuously consumes power is required to recirculate exhaust gas to the engine. Prior art literature

[0013] Korean Patent Publication No. 10-2007048 (Date of publication: August 2, 2019) The problem to be solved

[0014] The problem that the present invention aims to solve is to solve the aforementioned problem.

[0015] Another objective of the present invention is to reduce the emission of harmful substances, such as nitrogen oxides, contained in exhaust gas with almost no separate power consumption.

[0016] Another objective of the present invention is to reduce the emission of harmful substances by recirculating exhaust gas, while simultaneously satisfying the output conditions required for the engine.

[0017] The problems of the present invention are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0018] To achieve the above objective, a gas engine heat pump according to an embodiment of the present invention comprises an engine that combusts a mixture of air and fuel, a first charger that compresses the mixture and supplies it to the engine, a first exhaust passage connected to the engine through which exhaust gas discharged from the engine flows, and a second charger that is driven by exhaust gas branching from the first exhaust passage to a second exhaust passage and compresses the exhaust gas discharged from the engine and supplies it to the engine. Accordingly, it is possible to reduce the emission of nitrogen oxides by recirculating exhaust gas without separate power consumption.

[0019] The first charger may include a first compressor that compresses the mixture and introduces it into the engine, and a first turbine installed in the first exhaust passage that receives exhaust gas passing through the first exhaust passage and drives the first compressor.

[0020] In addition, the second charger may include a second turbine that drives the second charger by receiving exhaust gas branched from the first exhaust path to the second exhaust path, and a second compressor that compresses the exhaust gas passing through the first turbine and / or the second turbine and introduces it into the engine.

[0021] The above gas engine heat pump may further include a first bypass valve that is installed to be openable and closable in the second exhaust passage and supplies a portion of the exhaust gas discharged from the engine and supplied to the first turbine to the second turbine when opened, and a control unit that controls the opening degree of the first bypass valve.

[0022] The above gas engine heat pump further includes a sensor for measuring the concentration of nitrogen oxides contained in the exhaust gas discharged from the engine, and the control unit can adjust the opening of the first bypass valve based on the concentration of nitrogen oxides measured by the sensor.

[0023] The control unit may open the first bypass valve when the concentration of the nitrogen oxide is above a reference concentration, increase the opening rate of the first bypass valve as the concentration of the nitrogen oxide increases within the limiting range of the exhaust gas supplied to the engine, and close the first bypass valve when the concentration of the nitrogen oxide is below the reference concentration.

[0024] The limiting range of exhaust gas supplied to the engine can be defined as a range in which the amount of exhaust gas supplied to the engine is 15% or less of the amount of mixture supplied to the engine.

[0025] The above gas engine heat pump may further include a third exhaust passage branched from the first exhaust passage and a second bypass valve installed in the third exhaust passage to be openable and closable, which, when opened, discharges a portion of the exhaust gas discharged from the engine and supplied to the first turbine to the outside.

[0026] The third exhaust passage may be positioned between the first exhaust passage and the second exhaust passage.

[0027] The control unit can adjust the opening rate of the second bypass valve so that when the current output of the engine differs from the required output of the engine by more than an error value, the difference between the current output and the required output becomes less than the error value.

[0028] A gas engine heat pump, wherein the control unit, when the current output differs from the required output by more than an error value and the concentration of nitrogen oxides is greater than or equal to a reference concentration, first adjusts the opening rate of the first bypass valve according to the concentration of nitrogen oxides, adjusting the opening rate of the first bypass valve in a direction that reduces the error value, and if the current output and the required output still differ by more than an error value, adjusts the opening rate of the second bypass valve so that the difference between the current output and the required output becomes less than the error value, and if the current output differs from the required output by more than an error value and the concentration of nitrogen oxides is less than the reference concentration, closes the first bypass valve and adjusts the opening rate of the second bypass valve so that the difference between the current output and the required output becomes less than the error value.

[0029] The above gas engine heat pump includes an exhaust gas heat exchanger that cools the exhaust gas discharged from the engine, and the second compressor can compress the exhaust gas that has passed through the exhaust gas heat exchanger.

[0030] The above gas engine heat pump includes an exhaust gas heat exchanger that cools the exhaust gas discharged from the engine, and the sensor may be positioned downstream of the exhaust gas heat exchanger.

[0031] The above gas engine heat pump may include a check valve through which exhaust gas compressed from the second charger and supplied to the engine passes.

[0032] Meanwhile, a gas engine heat pump according to another embodiment of the present invention may include an engine that burns a mixture of air and fuel, a first charger that is driven by receiving exhaust gas discharged from the engine and compresses the mixture to supply it to the engine, and a second charger that is driven by receiving a branched portion of the exhaust gas discharged from the engine and supplied to the first charger and compresses the exhaust gas discharged from the engine to supply it to the engine.

[0033] Specific details of other embodiments are included in the detailed description and drawings. Effects of the invention

[0034] According to the gas engine heat pump of the present invention, one or more of the following effects are present.

[0035] First, it has the advantage of reducing the emission of harmful substances, such as nitrogen oxides contained in exhaust gas, with almost no separate power consumption.

[0036] Second, it has the advantage of reducing the emission of harmful substances by recirculating exhaust gases, while simultaneously meeting the output requirements of the engine.

[0037] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims. Brief explanation of the drawing

[0038] FIG. 1 is a schematic diagram of a gas engine heat pump system according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating the flow of a mixture and exhaust gas according to one embodiment within the gas engine heat pump of FIG. 1. FIG. 3 is a schematic diagram illustrating the flow of a mixture and exhaust gas according to another embodiment within the gas engine heat pump of FIG. 1. FIG. 4 is a block diagram of the control configuration of the gas engine heat pump of the present invention. FIG. 5 is a flowchart of a control method for a gas engine heat pump according to one embodiment of the present invention. FIG. 6 illustrates an embodiment of the flowchart of FIG. 5. FIG. 7 is a flowchart of a control method for a gas engine heat pump according to another embodiment of the present invention. FIG. 8 illustrates an embodiment of the flowchart of FIG. 7. FIG. 9 is a flowchart of a control method for a gas engine heat pump according to another embodiment of the present invention. Figure 10 shows the experimental results regarding whether harmful substances in exhaust gas are reduced through the gas engine heat pump according to the present invention. Specific details for implementing the invention

[0039] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0040] Spatially relative terms such as "below," "beneath," "lower," "above," and "upper" may be used to facilitate the description of the relationship between one component and another, as illustrated in the drawings. Spatially relative terms should be understood as encompassing different orientations of the component during use or operation, in addition to the orientations depicted in the drawings. For example, if a component depicted in a drawing is inverted, a component described as "below" or "beneath" of another component may be placed "above" of that other component. Therefore, the exemplary term "below" may encompass both the lower and upper directions. Components may also be oriented in other directions, and accordingly, spatially relative terms may be interpreted according to the orientation.

[0041] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components, steps, and / or actions to the mentioned components, steps, and / or actions.

[0042] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0043] In the drawings, the thickness or size of each component is exaggerated, omitted, or schematically depicted for the convenience and clarity of explanation. Additionally, the size and area of ​​each component do not entirely reflect their actual size or area.

[0045] Hereinafter, the present invention will be described with reference to the drawings for explaining the gas engine heat pump of the present invention by way of embodiments of the present invention.

[0047] Referring to FIG. 1 below, the gas engine heat pump according to the present invention includes an engine (5) that drives a compressor (not shown) by burning a mixture of air and fuel.

[0048] The above fuel and air can be supplied through a fuel supply device and an air supply device, respectively. And, the supplied fuel and air can be mixed in a mixer through a mixer (1).

[0049] The above air supply device may include an air filter (2) for purifying air. Additionally, the above air supply device may include a silencer (3) for reducing noise caused by air inflow. Furthermore, the above fuel supply device may include a zero governor (not shown) for supplying fuel at a constant pressure.

[0050] Meanwhile, the gas engine heat pump of the present invention includes a first charger (4) that compresses the mixture discharged after air and fuel are mixed in the mixer (1) and supplies it to the engine (5). The first charger (4) can compress the air and fuel from the mixer (1) to a pressure higher than atmospheric pressure by adjusting the rotational speed.

[0051] The first charger (4) may be a turbocharger driven by exhaust gas discharged from the engine. The first charger (4) may include a first compressor (4b) that compresses the mixture and introduces it into the engine (5), and a first turbine (4a) that receives exhaust gas discharged from the engine (5) and drives the first compressor (4b). The first compressor (4b) may be positioned upstream of the engine (5) and connected to the intake side of the engine (5). The first turbine (4a) may be positioned downstream of the engine (5) and receive exhaust gas from the engine (5).

[0052] Meanwhile, the gas engine heat pump may include a control means (6). For example, the control means (6) may be equipped with a valve to which an electronic throttle control (ETC) method is applied. Fuel and air are mixed in a mixer (1) and can be pressurized to a high pressure in a first charger (4), which is a supercharging means. Subsequently, as the opening degree of the control means (6) is adjusted, the amount of the mixture can be adjusted and supplied to the engine (5).

[0053] And, the gas engine heat pump of the present invention includes a second charger (7) that is driven by exhaust gas discharged from the engine (5) and branches off, and compresses the exhaust gas discharged from the engine and supplies it to the engine (5).

[0054] Meanwhile, the exhaust passage connected downstream of the engine (5) is branched into multiple passages, and thus, the exhaust gas discharged from the engine (5) can flow through the multiple passages.

[0055] Specifically, the gas engine heat pump of the present invention may include a first exhaust passage (21) connected to an engine (5) through which exhaust gas discharged from the engine flows. Additionally, the gas engine heat pump may include at least one of a second exhaust passage (23) and a third exhaust passage (25), which are bypass passages branching from the first exhaust passage (21).

[0056] At this time, the second charger (7) is driven by exhaust gas branched from the first exhaust passage (21) to the second exhaust passage (23), and compresses the exhaust gas discharged from the engine (5) and supplies it to the engine (5).

[0057] Meanwhile, if the first charger (4) is a turbocharger, the first turbine (4a) is installed on the first exhaust passage (21) to receive exhaust gas passing through the first exhaust passage (21) and drive the first compressor (4b).

[0058] And, the second charger (7) may include a second compressor (7b) that compresses exhaust gas and recirculates it into the engine, and a second turbine (7a) that receives exhaust gas discharged from the engine (5) and drives the second compressor (7b).

[0059] Specifically, the second turbine (7a) can drive the second charger (7) by receiving exhaust gas branched from the first exhaust passage (21) to the second exhaust passage (23). And, the second compressor (7b) can compress the exhaust gas that has passed through the first turbine (4a) and / or the second turbine (4b) and supply it to the engine (5).

[0060] The second compressor (7b) can compress exhaust gas discharged from the engine (5). That is, the second compressor (7b) can compress exhaust gas discharged from the engine (5) and passed through at least one of the first exhaust passage (21) and the second exhaust passage (23), and introduce it into the engine (5). In addition, when the gas engine heat pump of the present invention is provided with a third exhaust passage (25), the second compressor (7b) can compress exhaust gas discharged from the engine (5) and passed through at least one of the first to third exhaust passages (21, 23, 25), and introduce it into the engine.

[0061] Accordingly, the second charger (7) can recirculate exhaust gas to the engine (5) without consuming separate power, and can reduce the amount of exhaust gas and the amount of nitrogen oxides in the exhaust gas.

[0062] Meanwhile, the gas engine heat pump of the present invention may include a first bypass valve (13) installed to be openable and closable in the second exhaust passage (23). The first bypass valve (13) may be an exhaust gas recirculation (EGR) device.

[0063] When the first bypass valve (13) is opened, a portion of the exhaust gas discharged from the engine and supplied to the first exhaust passage (21) can be introduced into the second exhaust passage (23) and supplied to the second turbine (7a). The first bypass valve (13) is connected to a control unit (30, see FIG. 4) so ​​that the opening degree can be precisely adjusted.

[0064] Accordingly, the amount of exhaust gas flowing into the first charger (4) can be controlled, thereby satisfying the load required by the engine (5). At the same time, as described above, there is an effect of reducing the amount of exhaust gas emitted.

[0065] Meanwhile, the gas engine heat pump of the present invention is a nitrogen oxide (NO₂) contained in the exhaust gas discharged from the engine (5).x It may include a sensor (9) for measuring the concentration of ). The sensor (9) can measure the concentration of nitrogen oxides contained in the exhaust gas that has passed through the first to third exhaust passages (21, 23, 25). The harmful substances that the sensor (9) can measure are not limited to nitrogen oxides.

[0066] And, the control unit (30, see FIG. 4) is connected to the sensor (9) and can receive the concentration of nitrogen oxide measured from the sensor (9). The control unit (30) can adjust the opening of the first bypass valve (13) based on the concentration of nitrogen oxide measured from the sensor (9).

[0067] Meanwhile, the gas engine heat pump of the present invention may include a second bypass valve (15) that is openable and closable in a third exhaust passage (25) branched from a first exhaust passage (21). When the second bypass valve (15) is opened, a portion of the exhaust gas discharged from the engine (5) and supplied to the first turbine (4a) can be discharged to the outside. The second bypass valve (15) is connected to a control unit (30, see FIG. 4) so ​​that the degree of opening can be precisely controlled.

[0068] Accordingly, the second bypass valve (15) can regulate the amount of exhaust gas supplied to the first charger (4) to satisfy the load conditions required for the engine (5).

[0069] The third exhaust passage (25), where the second bypass valve (15) is installed, can be positioned between the first exhaust passage (21) and the second exhaust passage (23). Accordingly, when both the first bypass valve (13) and the second bypass valve (15) are opened, the exhaust gas that is not supplied to the first turbine (4b) first enters the second exhaust passage (23), which is a path for reducing nitrogen oxides, rather than the third exhaust passage (25), which is a path for simply discharging exhaust gas to the outside.

[0070] Meanwhile, the gas engine heat pump of the present invention may include an exhaust gas heat exchanger (8) for cooling exhaust gas discharged from an engine (5). Cooling water that exchanges heat with the exhaust gas may flow through the exhaust gas heat exchanger (8). The exhaust gas may pass through the exhaust gas heat exchanger (8) and be discharged to the outside in a cooled state. In order to reduce noise when the exhaust gas is discharged to the outside, the gas engine heat pump may further be equipped with a muffler (not shown).

[0071] The exhaust gas heat exchanger (8) can exchange heat with the exhaust gas that has passed through the first turbine (4a) and / or the second turbine (7a). The exhaust gas heat exchanger (8) can cool the exhaust gas by exchanging heat with the exhaust gas that has passed through at least one of the first to third exhaust passages (21, 23, 25).

[0072] And, the second compressor (7b) can compress the exhaust gas that has passed through the exhaust gas heat exchanger (8). At this time, the second compressor (7b) may be positioned downstream of the exhaust gas heat exchanger (8). And, the exhaust gas that has passed through the exhaust gas heat exchanger (8) may be branched so that some of it is discharged to the outside, and some of it is supplied to the second compressor (7b) as the second compressor (7b) is driven.

[0073] More specifically, the first to third exhaust passages (21, 23, 25) can be combined into a single fourth exhaust passage (27). The fourth exhaust passage (27) passes through an exhaust gas heat exchanger (8), allowing the cooling water flowing through the exhaust gas heat exchanger (8) and the exhaust gas flowing through the fourth exhaust passage (27) to exchange heat with each other. At this time, a recirculation passage (29) is formed by branching off from the fourth exhaust passage (27), and a second compressor (7b) can be installed in the recirculation passage (29). Accordingly, when the second charger (7) is driven, some of the exhaust gas passing through the fourth exhaust passage (27) can be branched off into the recirculation passage (29) and supplied to the second compressor (7b).

[0074] Accordingly, the exhaust gas is compressed, and the high-temperature exhaust gas discharged from the engine (5) can be supplied to the engine (5) in a cooled state by the exhaust gas heat exchanger (8) before being recirculated to the engine (5) by the second charger (7). Thus, a reduction in the efficiency of the engine (5) can be prevented.

[0075] At this time, the sensor (9) may be placed downstream of the exhaust gas heat exchanger (8). The sensor (9) may be placed in the fourth exhaust passage (27).

[0076] Generally, the temperature of the exhaust gas immediately after being discharged from the engine (5) is between about 400 and 800 degrees, so when the sensor (9) measures the concentration of harmful gases contained in the high-temperature exhaust gas, there is a risk that the sensor (9) device may be damaged. Therefore, the sensor (9) can be cooled by the exhaust gas heat exchanger (8) to measure the concentration of harmful gases contained in the exhaust gas at a temperature between about 50 and 200 degrees, thereby reducing this problem.

[0077] Meanwhile, the gas engine heat pump of the present invention may include a check valve (17) through which exhaust gas compressed from the second charger (7) and supplied to the engine (5) passes. The check valve may be connected to the upstream side of the control means (6).

[0078] For example, when driving the engine (5), the amount of exhaust gas supplied to the first charger (4) to supercharge the air may be greater than the amount of exhaust gas supplied to the second charger (4). Accordingly, the supercharging pressure of the mixture compressed in the first charger (4) may be much greater than the supercharging pressure of the exhaust gas compressed from the second charger (7) and supplied to the engine (5). In this case, the exhaust gas may not be recirculated and may flow back in the second intake passage (24).

[0079] To prevent such problems, the check valve (17) can allow exhaust gas to flow only in the direction supplied to the engine (5) and prevent exhaust gas from flowing in the reverse direction. Accordingly, it is possible to prevent the exhaust gas recirculated to the engine (5) from flowing back to the second compressor (7b) due to the pressure of the mixture and the exhaust gas.

[0081] Referring to FIGS. 2 and FIGS. 3 below, as described above, the mixture of air and fuel mixed in the mixer (1) can be introduced into the engine (5) by driving the first charger (4). The amount of mixture introduced into the engine (5) can be precisely controlled by the control means (6).

[0082] Referring to FIG. 2, the first bypass valve (13) and the second bypass valve (15) can be closed. Accordingly, exhaust gas discharged from the engine (5) flows only through the first exhaust passage (21) and is supplied to the first turbine (4a), and the first turbine (4a) can drive the first compressor (4b) to introduce the mixture into the engine (5). The exhaust gas that has passed through the first turbine (4a) can be cooled by passing through the exhaust gas heat exchanger (8) and then discharged to the outside. This may be the case where the output required for the engine (5) is at its maximum.

[0083] Meanwhile, referring to FIG. 3, the first bypass valve (13) can be opened and the second bypass valve (15) can be closed. Accordingly, a portion of the exhaust gas discharged from the engine (5) and flowing into the first exhaust passage (21) can be diverted into the second exhaust passage (23). The amount of diverted exhaust gas can be controlled according to the opening of the second bypass valve (13).

[0084] The exhaust gas branched into the second exhaust passage (23) is supplied to the second turbine (7a), and the second turbine (7a) can drive the second compressor (7b). The exhaust gas passing through the first and second exhaust passages (21, 23) flows into the fourth exhaust passage (27), and a portion of the exhaust gas flowing through the fourth exhaust passage (27) is branched into the recirculation passage (29) and supplied to the second compressor (7b). The supplied exhaust gas can be compressed by the second compressor (7b) and supplied to the engine (5).

[0085] Meanwhile, although omitted in FIGS. 2 and 3 above, in order to match the current output of the engine (5) to the output required of the engine (5), the second bypass valve (15) installed in the third exhaust passage (25) is opened so that a portion of the exhaust gas flowing toward the first turbine (4a) can be introduced into the third exhaust passage (25).

[0087] Referring to FIG. 4 below, the control unit (30) is connected to at least one of the engine (5), the control means (6), the sensor (9), the first bypass valve (13), and the second bypass valve (15), and can control the operation of the connected components. In this case, if the first charger (4) is a supercharger, the control unit (30) can also be separately connected to the first charger (4).

[0088] The control unit (30) can adjust the rotational speed of the first charger (4). For example, if the first charger (4) is a supercharger, the control unit (30) can directly apply power to the first charger (4) to adjust the rotational speed of the first charger (4). As another example, if the first charger (4) is a turbocharger, the control unit (30) can adjust the rotational speed of the first charger (4) by adjusting the opening of the first bypass valve (13) and / or the second bypass valve (15).

[0089] The control unit (30) can control the opening of the control means (6). The amount of high-pressure mixture supplied to the engine (5) through the control means (6) can be precisely controlled by the control unit (30).

[0090] The control unit (30) can receive information from the engine (5) regarding the current output and required output of the engine (5). To this end, the engine (5) may be equipped with a sensor (not shown) inside.

[0092] Referring to FIG. 5 below, a sensor (9) of a gas engine heat pump according to an embodiment of the present invention can measure the concentration of nitrogen oxides in the exhaust gas discharged from the engine (5) (S11). Subsequently, a control unit (30) can receive the concentration value of nitrogen oxides measured by the sensor (9). Based on the concentration of nitrogen oxides measured by the sensor (9), the control unit (30) can adjust the opening degree of the first bypass valve (13) (S12 and S13).

[0093] More specifically, the control unit (30) can compare the concentration of nitrogen oxides (current concentration) measured by the sensor (9) with a reference concentration (S12). Subsequently, if the current concentration of nitrogen oxides is greater than or equal to the reference concentration (Yes in S12), the control unit (30) can open the first bypass valve (13), but can adjust the opening rate of the first bypass valve (13) according to the concentration of nitrogen oxides (S13). Then, if the concentration of nitrogen oxides is less than the reference concentration (No in S12), the control unit (30) can close the first bypass valve (13) (S14).

[0094] That is, the control unit (30) can increase the opening rate of the first bypass valve (13) as the concentration of the nitrogen oxide increases. In other words, the opening rate of the first bypass valve (13) can be decreased as the concentration of the nitrogen oxide decreases.

[0095] At this time, if the exhaust gas supplied to the engine (5) becomes too large compared to the mixture, the amount of mixture flowing into the engine (5) decreases, and an efficiency problem may occur. Therefore, it is desirable to appropriately limit the opening rate of the first bypass valve (13). That is, the opening rate of the first bypass valve (13) can be increased within the limiting range of the exhaust gas supplied to the engine (5). The opening rate of the first bypass valve (13) according to the exhaust gas limiting range may be less than X% (S13).

[0096] For example, the limiting range of exhaust gas supplied to the engine (5) can be defined as a range in which the amount of exhaust gas supplied to the engine is 15% or less of the amount of mixture supplied to the engine. At this time, the opening rate of the first bypass valve (13) may be about 15%.

[0098] Referring to FIG. 6 below, an embodiment of the process S13 of FIG. 5 is schematically illustrated.

[0099] The control unit (30) can compare the concentration of nitrogen oxides (current concentration) measured by the sensor (9) with a reference concentration (S12). Afterwards, if the current concentration of nitrogen oxides is greater than or equal to the reference concentration (Yes in S12), the control unit (30) opens the first bypass valve (13), but can adjust the opening rate of the first bypass valve (13) according to the concentration of nitrogen oxides within the limiting range of the exhaust gas supplied to the engine (S13).

[0100] For example, if the emission of nitrogen oxides is 1000 ppm or more (Yes in S131), the control unit (30) can open the first bypass valve (S132) by 5%. Afterwards, the control unit (30) can return to the previous step and compare the current concentration of nitrogen oxides with the reference concentration (S12).

[0101] Afterwards, if the current concentration of nitrogen oxides is greater than or equal to the reference concentration (Yes in S12), the nitrogen oxide emission is less than 1000 ppm (No in S131), or is greater than or equal to 500 ppm (Yes in S133), the control unit (30) can open the first bypass valve (S132) by 2% (S134). Afterwards, the control unit can return to the previous step and compare the current concentration of nitrogen oxides with the reference concentration (S12).

[0102] Afterwards, the control unit (30) can repeat the same process to adjust the opening rate of the first bypass valve (13) according to the amount of nitrogen oxides emitted. Then, if the current concentration of nitrogen oxides is less than the reference concentration (No in S12), the control unit (30) can close the first bypass valve (13).

[0104] Referring to FIG. 7 below, the control unit (30) can receive the current output of the engine (5) and the output required of the engine (5) (S21). Afterwards, the control unit (30) can compare the output required of the engine (5) with the current output (S22).

[0105] At this time, if the difference between the current output and the required output is greater than or equal to the error value (q) (Yes in S22), the control unit (30) can adjust the opening rate of the second bypass valve (15) according to the required output so that the difference between the current output and the required output becomes less than the error value (q) (S23).

[0106] Afterwards, the control unit (30) continuously compares the current output and the required output of the engine (5) again, and if the difference between the current output and the required output is greater than or equal to the error value (q), the above process is repeated, and if the difference is less than the error value (q) (No in S22), the opening rate of the second bypass valve (15) is maintained and terminated.

[0108] Referring to FIG. 8 below, an embodiment of the process S23 of FIG. 7 is schematically illustrated.

[0109] The control unit (30) compares the current output of the engine (5) with the required output, and if the difference between the current output and the required output is less than the error value (q) (No in S22), it terminates while maintaining the current opening rate of the second bypass valve (15). Then, if the difference between the current output and the required output is greater than or equal to the error value (q) (Yes in S22), it can determine whether the current output is greater than or less than the required output (S231).

[0110] If the current output is greater than the required output (Yes in S231), the control unit (30) can open the second bypass valve (15) by Y% (S232). Afterwards, if the difference between the current output and the required output is still greater than the error value (q) (Yes in S233), the control unit (30) can increase the opening rate of the second bypass valve (15) by a (S234). That is, the control unit (30) opens the second bypass valve (15) by (Y+a)% and then compares the current output of the engine (5) with the required output again (S233).

[0111] Afterwards, if the difference between the current output and the required output is still greater than or equal to the error value (q) (Yes in S233), the control unit (30) repeats the process of increasing the opening rate of the second bypass valve (15) by a. Then, if the difference between the current output and the required output becomes less than the error value (q), the process terminates (No in S233).

[0112] If the current output is less than the required output (No in S231), the control unit (30) can open the second bypass valve (15) by Z% (S235). At this time, the Z value may be smaller than the Y value. Subsequently, if the difference between the current output and the required output is still greater than or equal to the error value (q) (Yes in S236), the control unit (30) can reduce the opening rate of the second bypass valve (15) by b (S237). That is, the control unit (30) opens the second bypass valve (15) by (Zb)% and then compares the current output and the required output of the engine (5) again (S236).

[0113] Afterwards, if the difference between the current output and the required output is still greater than or equal to the error value (q) (Yes in S236), the control unit (30) repeats the process of decreasing the opening rate of the second bypass valve (15) by b. Then, if the difference between the current output and the required output becomes less than the error value (q), the process terminates (No in S236). The above series of control processes can be implemented as fuzzy control.

[0115] Referring to FIG. 9 below, the control unit (30) of the present invention receives the current output and the required output from the engine (5) and receives the concentration of nitrogen oxides from the sensor (9) (S31). Then, the difference between the current output of the engine (5) and the required output is compared (S32). If the difference between the current output and the required output is less than the error value (q), the opening of the current first and second bypass valves (13, 15) is maintained and terminated (No in S32). At this time, if the difference between the current output and the required output is greater than or equal to the error value (q) (Yes in S32), the current concentration of nitrogen oxides contained in the exhaust gas can be compared with the reference concentration (S33).

[0116] Subsequently, if the current concentration of nitrogen oxides is above the reference concentration (Yes in S33), the control unit (30) opens the first bypass valve (13), but can adjust the opening rate of the first bypass valve (13) according to the concentration of nitrogen oxides (S13a). Accordingly, there is an advantage in that the emission of nitrogen oxides is reduced while matching the current output of the engine (5) with the required output. The process of adjusting the opening rate of the first bypass valve (13) according to the concentration of nitrogen oxides may be the same as the aforementioned step S13 (see FIG. 5 and FIG. 6).

[0117] At this time, for example, if the opening rate of the first bypass valve (13) according to the nitrogen oxide concentration is 10%, but the opening rate of the first bypass valve (13) such that the difference between the current output and the required output of the engine (5) is less than the error value (q) is 5%, then when the first bypass valve (13) is opened by 10%, the difference between the current output and the required output can be greater than or equal to the error value (q).

[0118] Accordingly, the first bypass valve (13) is opened, but the opening rate may be limited by considering the limiting range of exhaust gas flowing into the engine (5) (see explanation in FIG. 5) and the range in which the error value (q) is reduced (S13a). Accordingly, the opening rate of the first bypass valve (13) may be less than X'% (S13a).

[0119] Afterwards, the control unit (30) compares the current output of the engine (5) with the required output again (S34), and if the difference is less than the error value (q), it terminates (No in S34). And, if the difference is still greater than or equal to the error value (q) (Yes in S34), the control unit (30) can adjust the opening rate of the second bypass valve (15) according to the required output so that the difference between the current output and the required output becomes less than the error value (q) (S23a).

[0120] Afterwards, the control unit (30) continuously compares the current output and the required output of the engine (5) again, and if the difference between the current output and the required output is greater than or equal to the error value (q), the above process is repeated, and if the difference is less than the error value (q) (No in S34), the opening rate of the second bypass valve (15) is maintained and terminated.

[0121] Meanwhile, the difference between the current output of the engine (5) and the required output is compared (S32). If the difference between the current output and the required output is greater than or equal to the error value (q) (Yes in S32) and the concentration of current nitrogen oxides contained in the exhaust gas is less than the reference concentration (No in S33), the control unit (30) closes the first bypass valve (13) and adjusts the opening rate of the second bypass valve (15) according to the required output so that the difference between the current output and the required output becomes less than the error value (q) (S23b). The process of adjusting the opening rate of the second bypass valve (15) according to the required output may be the same as the aforementioned step S23 (see FIG. 7 and FIG. 8). Afterward, the process following step S34 is repeated. As described above, the explanation of this is omitted below.

[0123] FIG. 10 shows the experimental results for a gas engine heat pump according to an embodiment of the present invention. In the gas engine heat pump of the present invention, the change in the concentration of harmful gases contained in the exhaust gas was measured by adjusting the change in the operating point of the engine and the opening rate of the first bypass valve (13).

[0124] Referring to FIG. 10 below, FIG. 10 (a), (b), and (c) does not show a significant difference in the amount of harmful gases (THC, CH4, CO) depending on the engine operating point or exhaust gas recirculation rate. However, in the case of carbon monoxide (CO), the change depending on the excess air ratio was prominent.

[0125] However, referring to FIG. 10 (d) below, nitrogen oxides (NO₂) depending on the change in the engine's operating point and exhaust gas recirculation rate xChanges in the concentration of ) show significant differences. This is because carbon dioxide, water vapor, etc. contained in the exhaust gas have high specific heat, so they absorb heat during combustion and lower the combustion temperature. In this experiment, in the case of nitrogen oxides, a reduction in nitrogen oxide emissions ranging from a minimum of 38.13% to a maximum of 85.26% was confirmed depending on the opening rate of the first bypass valve.

[0127] Although preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above. Various modifications are possible by those skilled in the art without departing from the essence of the invention as claimed in the patent claims, and such modifications should not be understood individually from the technical spirit or perspective of the present invention. Explanation of the symbols

[0129] 1: Mixer 4: 1st Charger 4a: 1st turbine 4b: 1st compressor 5: Engine 7: Second charger 7a: 2nd turbine 7b: 2nd compressor 8: Heat exchanger 9: Sensor 13: 1st bypass valve 15: 2nd bypass valve 17: Check valve 21: First exhaust passage 23: 2nd exhaust passage 25: 3rd exhaust passage 30: Control unit

Claims

Claim 1 An engine that burns a mixture of air and fuel; a first charger that compresses the mixture and supplies it to the engine; a first exhaust passage connected to the engine through which exhaust gas discharged from the engine flows; and a second charger that is driven by exhaust gas branching from the first exhaust passage to a second exhaust passage and compresses the exhaust gas discharged from the engine and supplies it to the engine, wherein the first charger includes a first compressor that compresses the mixture and introduces it into the engine; and a first turbine installed in the first exhaust passage to receive exhaust gas passing through the first exhaust passage and drive the first compressor, and the second charger includes a second turbine that receives exhaust gas branching from the first exhaust passage to a second exhaust passage and drives the second charger. A gas engine heat pump comprising: a second compressor that compresses exhaust gas passing through the first turbine and / or the second turbine and introduces it into the engine; a first bypass valve installed in the second exhaust passage so as to be openable and closable, which, when opened, supplies a portion of the exhaust gas discharged from the engine and supplied to the first turbine to the second turbine; a third exhaust passage branching from the first exhaust passage; and a second bypass valve installed in the third exhaust passage so as to be openable and, when opened, discharges a portion of the exhaust gas discharged from the engine and supplied to the first turbine to the outside, wherein the third exhaust passage is a gas engine heat pump disposed between the first exhaust passage and the second exhaust passage. Claim 2 delete Claim 3 delete Claim 4 A gas engine heat pump according to claim 1, further comprising a control unit for controlling the opening degree of the first bypass valve. Claim 5 A gas engine heat pump according to claim 4, further comprising a sensor for measuring the concentration of nitrogen oxides contained in the exhaust gas emitted from the engine, wherein the control unit adjusts the opening of the first bypass valve based on the concentration of nitrogen oxides measured by the sensor. Claim 6 A gas engine heat pump according to claim 5, wherein the control unit opens the first bypass valve when the concentration of the nitrogen oxide is above a reference concentration, increases the opening rate of the first bypass valve as the concentration of the nitrogen oxide increases within the limiting range of the exhaust gas supplied to the engine, and closes the first bypass valve when the concentration of the nitrogen oxide is below the reference concentration. Claim 7 A gas engine heat pump according to claim 6, wherein the limiting range of exhaust gas supplied to the engine is defined as a range in which the amount of exhaust gas supplied to the engine is 15% or less of the amount of mixture supplied to the engine. Claim 8 delete Claim 9 delete Claim 10 In claim 5, the control unit adjusts the opening rate of the second bypass valve so that when the current output of the engine differs from the required output of the engine by more than an error value, the difference between the current output and the required output becomes less than the error value. Claim 11 A gas engine heat pump according to claim 10, wherein the control unit, when the current output differs from the required output by more than an error value and the concentration of nitrogen oxides is greater than or equal to a reference concentration, first adjusts the opening rate of the first bypass valve according to the concentration of nitrogen oxides, and adjusts the opening rate of the first bypass valve in a direction that reduces the error value, and when the current output and the required output still differ by more than an error value, adjusts the opening rate of the second bypass valve so that the difference between the current output and the required output becomes less than the error value, and when the current output differs from the required output by more than an error value and the concentration of nitrogen oxides is less than the reference concentration, closes the first bypass valve and adjusts the opening rate of the second bypass valve so that the difference between the current output and the required output becomes less than the error value. Claim 12 In claim 1, the gas engine heat pump includes an exhaust gas heat exchanger for cooling the exhaust gas discharged from the engine, and the second compressor compresses the exhaust gas that has passed through the exhaust gas heat exchanger. Claim 13 In claim 5, the exhaust gas heat exchanger for cooling the exhaust gas discharged from the engine is included, and the sensor is a gas engine heat pump disposed downstream of the exhaust gas heat exchanger. Claim 14 A gas engine heat pump according to claim 1, comprising a check valve through which exhaust gas compressed from the second charger and supplied to the engine passes. Claim 15 delete

Images