Natural gas / methanol dual-fuel engine and vehicle

Abstract

The invention discloses a natural gas / methanol dual-fuel engine and a vehicle, and belongs to the technical field of vehicles. The natural gas / methanol dual-fuel engine comprises a natural gas supply assembly, a methanol supply assembly, an air supply assembly and a combustion assembly. The natural gas supply assembly is used for supplying natural gas; the methanol supply assembly is used for heating and converting liquid methanol into methanol steam; the air supply assembly is used for supplying air; the input end of the combustion assembly is connected to the output end of the natural gas supply assembly, the output end of the methanol supply assembly and the output end of the air supply assembly, and the combustion assembly is used for uniformly mixing and combusting natural gas, methanol steam and air, or natural gas and air, or methanol steam and air. According to the natural gas / methanol dual-fuel engine, natural gas or methanol or both of natural gas and methanol can be selected as fuel according to actual combustion conditions, the problem that low-temperature starting is difficult can be solved, and the service life can be prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicles, in particular to a natural gas / methanol dual-fuel engine and vehicle. BACKGROUND

[0002] Natural gas has certain economic advantages as the fuel of an engine, and can meet the pursuit of most vehicles for economy and working stability. However, the price market of natural gas is not very stable at present, and vehicles using natural gas as the single fuel will inevitably have the problem of cost increase when encountering the changeable price of natural gas; therefore, a technical scheme of "one vehicle, two fuel choices" is usually realized by combining liquid methanol fuel.

[0003] However, due to the high ignition temperature and large latent heat of vaporization of liquid methanol, the engine will have the problem of difficult starting in a low-temperature environment; and due to the high boiling point of liquid methanol being higher than the normal atmospheric temperature, it is easy to cause serious wear of the combustion cylinder in the engine, and also increase the oil consumption of the engine, affecting the service life of the engine.

[0004] In view of the above, it is urgent to design a natural gas / methanol dual-fuel engine and vehicle to solve the above problems. SUMMARY

[0005] The present application aims to provide a natural gas / methanol dual-fuel engine and vehicle, which can select natural gas or methanol or both natural gas and methanol as the fuel according to the actual combustion condition, and can solve the problem of difficult starting in a low-temperature environment, and can improve the service life.

[0006] To achieve this purpose, the present application adopts the following technical scheme:

[0007] A natural gas / methanol dual-fuel engine, comprising:

[0008] a natural gas supply assembly for supplying natural gas;

[0009] a methanol supply assembly for heating liquid methanol to convert it into methanol vapor;

[0010] an air supply assembly for supplying air;

[0011] a combustion assembly, an input end of the combustion assembly being connected to an output end of the natural gas supply assembly, an output end of the methanol supply assembly and an output end of the air supply assembly, the combustion assembly being used for uniformly mixing natural gas, methanol vapor and air, or natural gas and air, or methanol vapor and air and performing combustion.

[0012] As an option, the natural gas supply assembly comprises, in sequence, a gas tank, a pressure reducing valve, a first buffer tank, a filter, a first stop valve and a first electrically controlled flow valve, the gas tank is used for storing natural gas, the pressure reducing valve is used for reducing the pressure of the natural gas, the first buffer tank is used for buffering the pressure of the natural gas, the filter is used for filtering impurities in the natural gas, the first stop valve is used for controlling the communication or disconnection between the first buffer tank and the combustion assembly, and the output end of the first electrically controlled flow valve is connected to the input end of the combustion assembly, and the first electrically controlled flow valve is used for regulating the mass flow of the natural gas entering the combustion assembly.

[0013] As an option, the methanol supply assembly comprises, in sequence, a storage tank, a check valve, a water bath vaporizer, a second buffer tank, a second stop valve and a second electrically controlled flow valve, the storage tank is used for storing liquid methanol, the water bath vaporizer is used for heating the liquid methanol flowing therethrough to convert the liquid methanol into methanol vapor, the check valve is configured to not allow the methanol vapor converted by the water bath vaporizer to flow back to the storage tank, the second buffer tank is used for buffering the pressure of the methanol vapor, the second stop valve is used for controlling the communication or disconnection between the second buffer tank and the combustion assembly, and the output end of the second electrically controlled flow valve is connected to the input end of the combustion assembly, and the second electrically controlled flow valve is used for regulating the mass flow of the methanol vapor entering the combustion assembly.

[0014] As an option, the water bath vaporizer comprises:

[0015] an outer cavity, a heating element and a temperature sensor, the heating element and the temperature sensor are both arranged in the outer cavity, the heating element is used for heating the liquid methanol flowing into the outer cavity to 75±5℃ to convert the liquid methanol into methanol vapor, and the temperature sensor is used for detecting the temperature in the outer cavity.

[0016] As an option, the methanol supply assembly further comprises:

[0017] a power supply element, used for supplying power to the heating element;

[0018] an electrically controlled switch, connected between the power supply element and the heating element, used for controlling the communication and disconnection between the power supply element and the heating element, and the electrically controlled switch is communicatively connected with the temperature sensor.

[0019] As an option, the methanol supply assembly further comprises:

[0020] a pressure stabilizing valve, connected between the output end of the pressure reducing valve and the input end of the storage tank, and the pressure stabilizing valve can keep the pressure of the liquid methanol in the storage tank within a preset range.

[0021] As an option, the air supply assembly comprises:

[0022] a first supercharger for compressing the inflow air, and at least part of the exhaust gas produced by the combustion assembly can push the first supercharger;

[0023] a intercooler connected downstream of the first supercharger, the intercooler for cooling the compressed air;

[0024] a first pressure sensor provided downstream of the intercooler, the first pressure sensor for detecting the pressure of the air;

[0025] a throttle valve provided between the first pressure sensor and the combustion assembly, the throttle valve for controlling the intake amount of air into the combustion assembly.

[0026] As an option, the combustion assembly comprises:

[0027] a mixer, the input end of the mixer being connected to the output end of the natural gas supply assembly, the output end of the methanol supply assembly and the output end of the air supply assembly, the mixer for uniformly mixing natural gas, methanol steam and air, or natural gas and air, or methanol steam and air;

[0028] a combustion cylinder provided downstream of the mixer, the combustion cylinder for burning natural gas, methanol steam and air, or natural gas and air, or methanol steam and air, and producing exhaust gas;

[0029] a second pressure sensor provided between the mixer and the combustion cylinder, the second pressure sensor for detecting the inlet pressure of the combustion cylinder.

[0030] As an option, the natural gas / methanol dual-fuel engine further comprises an exhaust gas supply assembly, the exhaust gas supply assembly comprising:

[0031] a second supercharger, at least part of the exhaust gas produced by the combustion cylinder flows into the second supercharger, the second supercharger for compressing the inflow exhaust gas;

[0032] a cooler provided downstream of the second supercharger, the cooler for cooling the exhaust gas compressed by the second supercharger;

[0033] an EGR valve connected between the cooler and the mixer, the EGR valve for controlling the communication and disconnection between the cooler and the mixer, the mixer can uniformly mix natural gas, methanol steam, exhaust gas and air, or natural gas, exhaust gas and air, or methanol steam, exhaust gas and air.

[0034] A vehicle comprising the natural gas / methanol dual fuel engine as described above.

[0035] The present application has the following advantages:

[0036] By supplying natural gas by the natural gas supply assembly, heating and converting liquid methanol into methanol vapor by the methanol supply assembly, and supplying air by the air supply assembly, and by making the combustion assembly uniformly mix natural gas, methanol vapor and air, or natural gas and air, or methanol vapor and air, and then combust, that is, natural gas or methanol or both natural gas and methanol can be selected as fuel according to actual combustion conditions, so as to improve the flexibility of fuel selection, thereby better adapting to the market with changing natural gas prices, and by heating to convert liquid methanol into methanol vapor, the methanol vapor is supplied to the combustion assembly for mixing and combustion, thereby avoiding the problem of difficult low-temperature starting due to the high ignition temperature and large latent heat of vaporization of liquid methanol, and also avoiding the problem of serious wear of the combustion assembly due to the boiling point of liquid methanol being higher than the normal atmospheric temperature, so as to improve the reliability and durability of the natural gas / methanol dual fuel engine, and reduce the oil consumption of the entire natural gas / methanol dual fuel engine, reduce the emission of unburned methanol vapor and HC, and thereby improve the service life of the entire natural gas / methanol dual fuel engine.

[0037] The vehicle of the present application, due to comprising the natural gas / methanol dual fuel engine as described above, can improve the flexibility of fuel selection, solve the problem of difficult starting in low-temperature environment, and reduce oil consumption, thereby prolonging the service life of the entire vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a structural schematic diagram of the natural gas / methanol dual fuel engine provided by the present application.

[0039] Reference signs:

[0040] 1 - natural gas supply assembly; 11 - gas storage tank; 12 - pressure reducing valve; 13 - first buffer tank; 14 - filter; 15 - first stop valve; 16 - first electrically controlled flow valve; 17 - first air inlet pipe;

[0041] 2 - methanol supply assembly; 21 - storage tank; 22 - one-way valve; 23 - water bath vaporizer; 231 - outer cavity; 232 - heating element; 233 - temperature sensor; 24 - second buffer tank; 25 - second stop valve; 26 - second electrically controlled flow valve; 27 - power supply element; 28 - electrically controlled switch; 29 - pressure stabilizing valve; 20 - second air inlet pipe;

[0042] 3-air supply assembly; 31-first supercharger; 32-intercooler; 33-first pressure sensor; 34-throttle valve; 35-third intake pipe;

[0043] 4-combustion assembly; 41-mixer; 42-combustion cylinder; 43-second pressure sensor; 44-fourth intake pipe;

[0044] 5-exhaust gas supply assembly; 51-second supercharger; 52-cooler; 53-EGR valve; 54-fifth intake pipe. DETAILED DESCRIPTION

[0045] All features disclosed in this specification, or all steps in the disclosed methods or processes, except mutually exclusive features and / or steps, can be combined in any manner.

[0046] Any feature disclosed in this specification, unless otherwise stated, may be replaced by an equivalent or similar alternative feature. That is, unless otherwise stated, each feature is merely an example of a set of equivalent or similar features. Throughout this specification, like reference numerals indicate like elements.

[0047] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved more clear, the technical solutions of the present invention are further described below with reference to the accompanying drawings and through specific implementation methods.

[0048] This embodiment proposes a natural gas / methanol dual-fuel engine and a vehicle incorporating the engine. The engine can select natural gas, methanol, or both as fuel, depending on actual combustion conditions. This provides a new fuel option in the current climate of volatile natural gas prices, addresses the issue of difficult starting at low temperatures, and extends the service life of the engine and the vehicle as a whole. Specifically, the vehicle can be a heavy-duty truck.

[0049] Specifically, if Figure 1 As shown, the natural gas / methanol dual-fuel engine includes a natural gas supply assembly 1, a methanol supply assembly 2, an air supply assembly 3 and a combustion assembly 4; wherein the natural gas supply assembly 1 is used to supply natural gas to the combustion assembly 4; the methanol supply assembly 2 is used to heat liquid methanol and convert it into methanol vapor, so as to provide the methanol vapor to the combustion assembly 4; the air supply assembly 3 is used to supply air to the combustion assembly 4; the input end of the combustion assembly 4 is connected to the output end of the natural gas supply assembly 1, the output end of the methanol supply assembly 2 and the output end of the air supply assembly 3, and the combustion assembly 4 is used to uniformly mix natural gas, methanol vapor and air, or natural gas and air, or methanol vapor and air and burn them.

[0050] By supplying natural gas by the natural gas supply assembly 1, heating and converting liquid methanol into methanol vapor by the methanol supply assembly 2, and supplying air by the air supply assembly 3, and by making the combustion assembly 4 uniformly mix natural gas, methanol vapor and air, or natural gas and air, or methanol vapor and air first, and then burning, that is, natural gas or methanol or both natural gas and methanol can be selected as fuel according to actual combustion conditions, the natural gas / methanol dual-fuel engine can work under single fuel or dual fuel, fuel selection flexibility can be improved, and the natural gas market price can be better adapted to the variable market, which is beneficial to cope with the variable natural gas market.

[0051] In the natural gas / methanol dual-fuel engine in the embodiment, liquid methanol is first converted into methanol vapor and then supplied to the combustion assembly 4 for mixing and burning, that is, liquid methanol is converted into methanol vapor by heating, and the methanol vapor is supplied to the combustion assembly 4 for mixing and burning, so that the problem of difficult low-temperature starting due to high ignition temperature and large latent heat of vaporization of liquid methanol can be avoided, and the problem of serious wear of the combustion assembly 4 due to the boiling point of liquid methanol being higher than the normal atmospheric temperature can also be avoided, so as to improve the reliability and durability of the natural gas / methanol dual-fuel engine, reduce the oil consumption of the entire natural gas / methanol dual-fuel engine, reduce the emission of unburned methanol vapor and HC, and further improve the service life of the entire natural gas / methanol dual-fuel engine.

[0052] In addition, by uniformly mixing natural gas, methanol vapor and air, or natural gas and air, or methanol vapor and air first, and then burning, on the one hand, the mixture of natural gas, air and methanol vapor can be more uniform, and the subsequent combustion can be more complete, so as to improve the thermal efficiency of the entire natural gas / methanol dual-fuel engine; on the other hand, by injecting liquid methanol into the combustion assembly 4 in the form of methanol vapor for mixing, the mixture of methanol vapor, air and natural gas can be more complete, so as to better ensure the subsequent complete combustion, and further improve the thermal efficiency of the entire natural gas / methanol dual-fuel engine.

[0053] It is worth mentioning that, due to the good complementarity between natural gas and methanol vapor, i.e. from the molecular formula of natural gas and methanol vapor, there is one carbon atom and four hydrogen atoms, but methanol vapor has one more oxygen atom than natural gas, so that the two fuels have similar combustion characteristics and physical and chemical properties, for example, the octane number of natural gas is 114, and the octane number of methanol vapor is 127; Therefore, both natural gas and methanol vapor can be ignited by a spark plug and pre-mixed diffusion combustion, that is, the same combustion assembly 4 can be used to realize the combustion of natural gas and methanol vapor, which is simple in structure and saves cost.

[0054] And, due to the boiling point of liquid methanol at standard atmospheric pressure is 64.7℃, so that the liquid methanol is relatively easy to heat and evaporate into methanol vapor; After the liquid methanol evaporates to form methanol vapor, it enters the combustion assembly 4 in the form of gas for mixed combustion, which is consistent with the combustion mode of natural gas; Thus, the same set of natural gas nozzles, electronic control system and the same three-way catalytic converter can be used as the emission aftertreatment of natural gas and methanol vapor, which makes the structure more simple and further saves the cost.

[0055] The natural gas supply assembly 1 is described in detail as follows:

[0056] Specifically, as shown in Figure 1 , the natural gas supply assembly 1 includes a gas tank 11, a pressure reducing valve 12, a first buffer tank 13, a filter 14, a first stop valve 15 and a first electric control flow valve 16 connected in series; wherein the gas tank 11 is used to store natural gas with a certain pressure, the pressure reducing valve 12 is used to reduce the pressure of the natural gas, so as to avoid that the natural gas with too high pressure directly enters the combustion assembly 4; the first buffer tank 13 is used to buffer the natural gas, so as to be able to adjust the pressure of the natural gas through the buffering effect, thereby stabilizing the pressure of the natural gas; the filter 14 is used to filter impurities in the natural gas, to ensure the cleanliness of the natural gas and avoid the problem of impurities blocking when injected into the combustion assembly 4, thereby ensuring the smoothness and reliability of the natural gas injection into the combustion assembly 4; the first stop valve 15 is used to control the communication or disconnection between the first buffer tank 13 and the combustion assembly 4, so as to supply or block the natural gas for the combustion assembly 4; the output end of the first electric control flow valve 16 is connected to the input end of the combustion assembly 4, and the first electric control flow valve 16 is used to regulate the mass flow of the natural gas entering the combustion assembly 4, so as to supply the required mass flow of natural gas for the combustion assembly 4. Wherein, the pressure reducing valve 12 can reduce the pressure of the natural gas to 0.8MPA-0.9MPA.

[0057] Specifically, as shown in Figure 1As shown, the gas storage tank 11, the pressure reducing valve 12, the first buffer tank 13, the filter 14, the first stop valve 15 and the first electrically controlled flow valve 16 are connected with each other through the first gas inlet pipe 17; and the pressure reducing valve 12, the first stop valve 15 and the first electrically controlled flow valve 16 can adopt the valve structure commonly used in the prior art.

[0058] The methanol supply assembly 2 will be described in detail as follows:

[0059] Specifically, as shown in Figure 1 the methanol supply assembly 2 comprises, which are connected in series, a storage tank 21, a one-way valve 22, a water bath vaporizer 23, a second buffer tank 24, a second stop valve 25 and a second electrically controlled flow valve 26; the storage tank 21 is used for storing liquid methanol; the water bath vaporizer 23 is used for heating the liquid methanol flowing therethrough so that the liquid methanol is converted into methanol vapor; the one-way valve 22 is configured to allow the liquid methanol to flow from the storage tank 21 to the water bath vaporizer 23 only, but not allow the methanol vapor converted by the water bath vaporizer 23 to flow back to the storage tank 21; the second buffer tank 24 is used for buffering the methanol vapor so as to be able to adjust the pressure of the methanol vapor through the buffering action, thereby stabilizing the pressure of the methanol vapor; the second stop valve 25 is used for controlling the communication or disconnection between the second buffer tank 24 and the combustion assembly 4, so as to be able to supply or block the methanol vapor for the combustion assembly 4; the output end of the second electrically controlled flow valve 26 is connected to the input end of the combustion assembly 4, and the second electrically controlled flow valve 26 is used for regulating the mass flow of the methanol vapor entering the combustion assembly 4, so as to be able to supply the required mass flow of the methanol vapor for the combustion assembly 4.

[0060] By arranging the one-way valve 22 between the storage tank 21 and the water bath vaporizer 23, the one-way valve 22 can prevent the methanol vapor generated by the water bath vaporizer 23 from flowing back to the storage tank 21 under abnormal conditions, thereby ensuring that the pressure in the storage tank 21 is relatively appropriate.

[0061] Further, as shown in Figure 1 the water bath vaporizer 23 comprises an outer cavity 231, a heating element 232 and a temperature sensor 233; the heating element 232 and the temperature sensor 233 are both arranged in the outer cavity 231; the heating element 232 is used for heating the liquid methanol flowing into the outer cavity 231 to 75±5℃, so that the liquid methanol is converted into methanol vapor; and the temperature sensor 233 is used for detecting the temperature in the outer cavity 231, so as to ensure that the temperature in the outer cavity 231 is relatively appropriate, thereby ensuring that the temperature in the outer cavity 231 can convert the liquid methanol into methanol vapor. The heating element 232 can be a heating rod in particular.

[0062] In particular, as shown in Figure 1As shown, the methanol supply assembly 2 further comprises a power supply 27 and an electrically controlled switch 28; wherein the power supply 27 is configured to supply power to the heating element 232, so that the heating element 232 generates heat after being powered on; the electrically controlled switch 28 is connected between the power supply 27 and the heating element 232, and is configured to control the connection and disconnection between the power supply 27 and the heating element 232, so that the heating element 232 can continuously heat or pause heating, and the electrically controlled switch 28 is in communication connection with the temperature sensor 233. Specifically, the power supply 27 can be a vehicle-mounted lithium battery, and other forms of power supply can also be used to assist the heating element 232 to heat; the electrically controlled switch 28 can be a common electrically controlled intelligent switch in the prior art.

[0063] Specifically, the power supply 27 supplies the power required by the heating element 232, and at this time the electrically controlled switch 28 is in a closed state, so that the power supply 27, the electrically controlled switch 28, the temperature sensor 233 and the heating element 232 cooperate with each other to complete the heating and vaporization of the liquid methanol in the outer cavity 231; that is, when the electrically controlled switch 28 is in the closed state, the heating element 232 can heat the liquid methanol in the outer cavity 231 to 75±5℃, and the boiling point of methanol is 64.7℃, so at this time 75℃ can make the liquid methanol vaporize to form methanol vapor. The temperature sensor 233 can monitor the temperature in the outer cavity 231 and transmit a temperature signal to the electrically controlled switch 28 to control the opening and closing of the electrically controlled switch 28.

[0064] Specifically, the power supply 27 is used as a power source to provide energy for the heating element 232; when the temperature sensor 233 detects that the temperature in the outer cavity 231 is lower than 70℃, the electrically controlled switch 28 is in a closed state, so that the heating element 232 is powered on to heat; when the temperature sensor 233 detects that the temperature in the outer cavity 231 reaches 80℃, the electrically controlled switch 28 is in an open state, so that the heating element 232 stops heating.

[0065] It is worth noting that after the liquid methanol passes through the water bath vaporizer 23, the methanol vapor formed is buffered in the second buffer tank 24, and the volume of the second buffer tank 24 is designed according to the displacement of the natural gas / methanol dual-fuel engine, so that the second buffer tank 24 can meet the changing mass flow demand of the methanol vapor under the transition buffering working condition.

[0066] The power supply 27 provides power for the heating element 232, that is, an external constant heating element 232 is used to stably supply heat, and in the way of vaporizing liquid methanol, the stability of the vaporization rate of liquid methanol can be ensured, and the situation of insufficient supply caused by sudden change of methanol vapor demand when the working condition is suddenly switched can be avoided, so that the supply amount of methanol vapor can be ensured to be sufficient and stable.

[0067] Further, as shown in FIG. 2, the water bath vaporizer 23 comprises a water tank 231 and a heating element 232; wherein the water tank 231 is configured to store water, and the heating element 232 is arranged in the water tank 231 and is configured to heat the water in the water tank 231 to generate steam; the water tank 231 is in communication connection with the second buffer tank 24, and the steam generated by the heating element 232 is introduced into the second buffer tank 24 through the water tank 231. Figure 1As shown, the methanol supply assembly 2 further comprises a pressure stabilizing valve 29, which is connected between the output end of the pressure reducing valve 12 and the input end of the storage tank 21, and is capable of keeping the pressure of the liquid methanol in the storage tank 21 within a preset range. The pressure stabilizing valve 29 can adopt a structure commonly used in the prior art.

[0068] By arranging the pressure stabilizing valve 29, the pressure of the natural gas after passing through the pressure reducing valve 12 is reduced to 0.8-0.9 MPa. At this time, a pressure stabilizing valve 29 is connected to the output end of the pressure reducing valve 12, and the other end of the pressure stabilizing valve 29 is connected to the high-pressure input end of the storage tank 21. In this way, the high pressure in the first air inlet pipe 17 for conveying natural gas can be used to directly provide pressure for the liquid methanol in the storage tank 21, so that the liquid methanol has a certain pressure for injection, thereby eliminating the need to install a pressurizing system, simplifying the structure, maximizing the use of pressure resources, and reducing costs.

[0069] Specifically, as shown in Figure 1 the storage tank 21, the one-way valve 22, the water bath vaporizer 23, the second buffer tank 24, the second stop valve 25, and the second electrically controlled flow valve 26 are connected to each other through the second air inlet pipe 20. The one-way valve 22, the second stop valve 25, and the second electrically controlled flow valve 26 can adopt a structure commonly used in the prior art.

[0070] The air supply assembly 3 will be described in detail as follows:

[0071] Specifically, as shown in Figure 1 the air supply assembly 3 comprises a first supercharger 31, an intercooler 32, a first pressure sensor 33, and a throttle valve 34 connected in series. The first supercharger 31 is used to compress and supercharge the air flowing in, i.e., the first supercharger 31 can increase the air intake to better improve the thermal efficiency of the entire natural gas / methanol dual-fuel engine. At least part of the exhaust gas generated by the combustion assembly 4 can drive the first supercharger 31 to work, thereby maximizing the use of exhaust gas resources. The intercooler 32 is connected downstream of the first supercharger 31 and is used to cool the compressed air. The first pressure sensor 33 is arranged downstream of the intercooler 32 and is used to detect the pressure of the air. The throttle valve 34 is arranged between the first pressure sensor 33 and the combustion assembly 4 and is used to control the air intake into the combustion assembly 4 to ensure that the air intake into the combustion assembly 4 is appropriate. The air enters the first supercharger 31 in the direction indicated by the arrow A in Figure 1 .

[0072] By arranging the intercooler 32 downstream of the first supercharger 31, since the air compressed by the first supercharger 31 becomes high-temperature and high-pressure gas, which causes the intake charge of the air to be small, the air compressed by the first supercharger 31 is cooled by the intercooler 32, so that the intake charge of the air can be appropriate.

[0073] Specifically, as shown in Figure 1 , the first supercharger 31, the intercooler 32, the first pressure sensor 33, and the throttle valve 34 are connected to each other by the third intake pipe 35; and the first supercharger 31, the intercooler 32, and the throttle valve 34 can adopt the structure commonly used in the prior art.

[0074] The combustion assembly 4 is described in detail as follows:

[0075] Specifically, as shown in Figure 1 , the combustion assembly 4 includes a mixer 41, a combustion cylinder 42, and a second pressure sensor 43; wherein the input end of the mixer 41 is connected to the output end of the natural gas supply assembly 1, the output end of the methanol supply assembly 2, and the output end of the air supply assembly 3, that is, the output end of the first electrically controlled flow valve 16, the output end of the second electrically controlled flow valve 26, and the output end of the throttle valve 34 are respectively connected to the input end of the mixer 41, so that the mixer 41 can uniformly mix natural gas, methanol vapor, and air, or natural gas and air, or methanol vapor and air; the combustion cylinder 42 is arranged downstream of the mixer 41, and is used for combusting natural gas, methanol vapor, and air, or natural gas and air, or methanol vapor and air, and generating exhaust gas; the second pressure sensor 43 is arranged between the mixer 41 and the combustion cylinder 42, and is used for detecting the inlet pressure of the combustion cylinder 42.

[0076] Specifically, as shown in Figure 1 , the mixer 41, the combustion cylinder 42, and the second pressure sensor 43 are connected to each other by the fourth intake pipe 44; and the mixer 41 and the combustion cylinder 42 can adopt the structure commonly used in the prior art.

[0077] The exhaust gas supply assembly 5 is described in detail as follows:

[0078] Specifically, as shown in Figure 1 , the natural gas / methanol dual-fuel engine further includes an exhaust gas supply assembly 5, which recycles part of the generated exhaust gas to the mixer 41, so that the exhaust gas is uniformly mixed in the mixer 41 and then delivered to the combustion cylinder 42 to participate in combustion again, so that the exhaust gas can be used more greatly, and the resource can be used maximally. Wherein, the exhaust gas generated by the combustion cylinder 42 is also partially discharged to the outside of the natural gas / methanol dual-fuel engine along the direction indicated by the arrow B in Figure 1 .

[0079] Further, as shown in Figure 1 The exhaust gas supply assembly 5 comprises a second supercharger 51, a cooler 52 and an EGR valve 53; at least part of the exhaust gas generated by the combustion cylinder 42 flows into the second supercharger 51, the second supercharger 51 is used for compressing the exhaust gas flowing in, that is, the second supercharger 51 can increase the intake amount of the exhaust gas, further improving the thermal efficiency of the entire natural gas / methanol dual fuel engine; the cooler 52 is arranged downstream of the second supercharger 51, and the cooler 52 is used for cooling the exhaust gas compressed by the second supercharger 51; the EGR valve 53 is connected between the cooler 52 and the mixer 41, and the EGR valve 53 is used for controlling the communication and disconnection between the cooler 52 and the mixer 41. The mixer 41 can uniformly mix natural gas, methanol vapor, exhaust gas and air, or natural gas, exhaust gas and air, or methanol vapor, exhaust gas and air. The EGR valve 53 specifically refers to an electromechanical integrated product installed on a diesel engine to control the amount of exhaust gas recirculated to the intake system.

[0080] By arranging the cooler 52 downstream of the second supercharger 51, because the exhaust gas will become high-temperature and high-pressure gas after being compressed and pressurized by the second supercharger 51, and the high-temperature and high-pressure gas will cause the intake charge of the exhaust gas to become small. Therefore, by cooling the compressed high-temperature and high-pressure gas through the cooler 52, the intake charge of the exhaust gas can be ensured to be relatively appropriate.

[0081] Specifically, as shown in Figure 1 The second supercharger 51, the cooler 52 and the EGR valve 53 are connected to each other through the fifth intake pipe 54; and the second supercharger 51, the cooler 52 and the EGR valve 53 can adopt the structure commonly used in the prior art.

[0082] The specific working process of the natural gas / methanol dual fuel engine in the embodiment is as follows, taking natural gas and methanol dual fuel as an example:

[0083] Firstly, the first stop valve 15 is opened, and the natural gas in the gas storage tank 11 flows into the mixer 41 in sequence through the pressure reducing valve 12, the first buffer tank 13, the filter 14, the first stop valve 15 and the first electric control flow valve 16; at the same time, the second stop valve 25 is opened, and the liquid methanol in the storage tank 21 enters the outer cavity 231 after passing through the one-way valve 22, at this time, the electric control switch 28 is in a closed state, and the heating element 232 can heat the liquid methanol in the outer cavity 231 to 75±5℃, so as to vaporize the liquid methanol to form methanol vapor in a temperature environment of 75℃; then, the methanol vapor flows into the mixer 41 in sequence through the second buffer tank 24, the second stop valve 25 and the second electric control flow valve 26.

[0084] And, the air flows into the mixer 41 after sequentially passing through the first supercharger 31, the intercooler 32 and the throttle valve 34; meanwhile, part of the exhaust gas flows into the mixer 41 after sequentially passing through the second supercharger 51, the cooler 52 and the EGR valve 53; at this time, the natural gas, the methanol vapor, the air and the exhaust gas are fully mixed and uniformly distributed in the mixer 41.

[0085] Then, the gas mixed and uniformly distributed in the mixer 41 flows into the combustion cylinder 42 to be combusted in the combustion cylinder 42. The theoretical air-fuel ratio of the methanol vapor, the natural gas and the air and the mixing ratio of the two fuels of the methanol vapor and the natural gas can be adjusted according to the actual working condition and the combustion requirement.

[0086] The natural gas / methanol dual-fuel engine in the embodiment can shorten the heat release time, improve the heat release rate and improve the economy by mixing the two fuels of the natural gas and the methanol vapor in the combustion cylinder 42; meanwhile, the total emission amount of the hydrocarbon and the nitrogen oxide can be reduced in the combustion process.

[0087] The natural gas / methanol dual-fuel engine in the embodiment can provide the pressure for the liquid methanol supply by the high pressure in the first air inlet pipe 17 for conveying the natural gas by using the pressure reducing valve 12 and the pressure stabilizing valve 29 which are used in cooperation, so that the pressurizing system does not need to be additionally installed in the methanol supply assembly 2, the structure is simple and the cost is low.

[0088] The natural gas / methanol dual-fuel engine in the embodiment can first mix the natural gas, the methanol vapor, the air and the exhaust gas in the mixer 41 to form the mixed gas with uniform temperature and concentration, and then the mixed gas is combusted in the combustion cylinder 42, so that the combustion is ensured to be complete, the combustion efficiency is improved, the misfire and knock limits of the natural gas / methanol dual-fuel engine are improved, and the thermal efficiency of the natural gas / methanol dual-fuel engine is improved.

[0089] The natural gas / methanol dual-fuel engine in the embodiment can heat and vaporize the liquid methanol into the methanol vapor by the heating member 232, and can maintain a good air intake impulse in a low temperature environment by the intercooler 32 and the cooler 52; and the electric control switch 28 can be opened and closed according to the temperature signal detected by the temperature sensor 233, so that the temperature in the outer cavity 231 is suitable, and the vaporization of the liquid methanol is ensured.

[0090] The natural gas / methanol dual fuel engine in the embodiment can ensure the stability of the liquid methanol vaporization rate and the sufficiency of the methanol vapor supply by adopting the external constant power supply 27 to provide power, and can effectively prevent the methanol vapor generated under abnormal conditions from flowing back into the storage tank 21 by setting the one-way valve 22, so that the pressure in the storage tank 21 can be better avoided from being too large.

[0091] The above is only the preferred embodiment of the present application, and for those skilled in the art, the specific implementation and application range can be changed according to the idea of the present application, and the content of the description should not be understood as a limitation of the present application.

Claims

1. A natural gas / methanol dual-fuel engine, characterized in that: include: A natural gas supply assembly (1) for supplying natural gas; A methanol supply component (2) is used to heat liquid methanol and convert it into methanol vapor; an air supply assembly (3) for supplying air; A combustion assembly (4), wherein the input end of the combustion assembly (4) is connected to the output end of the natural gas supply assembly (1), the output end of the methanol supply assembly (2), and the output end of the air supply assembly (3); the combustion assembly (4) is used to uniformly mix natural gas, methanol vapor and air, or natural gas and air, or methanol vapor and air, and burn them.

2. The natural gas / methanol dual-fuel engine according to claim 1, characterized in that: The natural gas supply assembly (1) comprises a gas storage tank (11), a pressure reducing valve (12), a first buffer tank (13), a filter (14), a first stop valve (15) and a first electrically controlled flow valve (16) connected in series in sequence, wherein the gas storage tank (11) is used to store natural gas, the pressure reducing valve (12) is used to reduce the pressure of natural gas, the first buffer tank (13) is used to slowly adjust the pressure of natural gas, the filter (14) is used to filter impurities in natural gas, the first stop valve (15) is used to control the connection or disconnection between the first buffer tank (13) and the combustion assembly (4), the output end of the first electrically controlled flow valve (16) is connected to the input end of the combustion assembly (4), and the first electrically controlled flow valve (16) is used to regulate the mass flow of natural gas entering the combustion assembly (4).

3. The natural gas / methanol dual-fuel engine according to claim 2, characterized in that: The methanol supply component (2) includes a storage tank (21), a one-way valve (22), a water bath vaporizer (23), a second buffer tank (24), a second stop valve (25) and a second electrically controlled flow valve (26) connected in series in sequence. The storage tank (21) is used to store liquid methanol. The water bath vaporizer (23) is used to heat the liquid methanol flowing through it to convert the liquid methanol into methanol vapor. The one-way valve (22) is configured to not allow the methanol vapor converted by heating in the water bath vaporizer (23) to flow back into the storage tank (21). The second buffer tank (24) is used to slowly adjust the pressure of the methanol vapor. The second stop valve (25) is used to control the connection or disconnection between the second buffer tank (24) and the combustion component (4). The output end of the second electrically controlled flow valve (26) is connected to the input end of the combustion component (4). The second electrically controlled flow valve (26) is used to regulate the mass flow of the methanol vapor entering the combustion component (4).

4. The natural gas / methanol dual-fuel engine according to claim 3, characterized in that: The water bath vaporizer (23) comprises: An outer cavity (231), a heating element (232) and a temperature sensor (233), wherein the heating element (232) and the temperature sensor (233) are both arranged in the outer cavity (231), the heating element (232) is used to heat the liquid methanol flowing into the outer cavity (231) to 75±5°C, so as to convert the liquid methanol into methanol vapor, and the temperature sensor (233) is used to detect the temperature in the outer cavity (231).

5. The natural gas / methanol dual-fuel engine according to claim 4, characterized in that: The methanol supply assembly (2) further comprises: a power supply element (27) for supplying power to the heating element (232); An electric control switch (28) is connected between the power supply (27) and the heating element (232). The electric control switch (28) is used to control the connection and disconnection between the power supply (27) and the heating element (232). The electric control switch (28) is also in communication connection with the temperature sensor (233).

6. The natural gas / methanol dual-fuel engine according to claim 3, characterized in that: The methanol supply assembly (2) further comprises: A pressure stabilizing valve (29) is connected between the output end of the pressure reducing valve (12) and the input end of the storage tank (21), and the pressure stabilizing valve (29) can keep the pressure of the liquid methanol in the storage tank (21) within a preset range.

7. The natural gas / methanol dual-fuel engine according to any one of claims 1 to 6, characterized in that: The air supply assembly (3) comprises: a first supercharger (31) for compressing the inflowing air, and at least a portion of the exhaust gas generated by the combustion of the combustion assembly (4) is capable of driving the first supercharger (31); an intercooler (32), connected downstream of the first supercharger (31), the intercooler (32) being used to cool the compressed air; a first pressure sensor (33), disposed downstream of the intercooler (32), the first pressure sensor (33) being used to detect air pressure; A throttle valve (34) is provided between the first pressure sensor (33) and the combustion assembly (4), and the throttle valve (34) is used to control the amount of air entering the combustion assembly (4).

8. The natural gas / methanol dual-fuel engine according to any one of claims 1 to 6, characterized in that: The combustion assembly (4) comprises: a mixer (41), wherein an input end of the mixer (41) is connected to an output end of the natural gas supply assembly (1), an output end of the methanol supply assembly (2), and an output end of the air supply assembly (3), and the mixer (41) is used to uniformly mix natural gas, methanol vapor and air, or natural gas and air, or methanol vapor and air; a combustion cylinder (42) disposed downstream of the mixer (41), the combustion cylinder (42) being used to burn natural gas, methanol vapor and air, or natural gas and air, or methanol vapor and air, and generate tail gas; A second pressure sensor (43) is provided between the mixer (41) and the combustion cylinder (42), and the second pressure sensor (43) is used to detect the inlet pressure of the combustion cylinder (42).

9. The natural gas / methanol dual-fuel engine according to claim 8, characterized in that: The natural gas / methanol dual-fuel engine further comprises an exhaust gas supply assembly (5), wherein the exhaust gas supply assembly (5) comprises: a second supercharger (51), into which at least a portion of the exhaust gas generated by combustion in the combustion cylinder (42) flows, and the second supercharger (51) is used to compress the inflowing exhaust gas; a cooler (52) disposed downstream of the second supercharger (51), the cooler (52) being used to cool the exhaust gas compressed by the second supercharger (51); An EGR valve (53) is connected between the cooler (52) and the mixer (41). The EGR valve (53) is used to control the connection and disconnection between the cooler (52) and the mixer (41). The mixer (41) can evenly mix natural gas, methanol vapor, tail gas and air, or natural gas, tail gas and air, or methanol vapor, tail gas and air.

10. A vehicle, characterized in that: It comprises the natural gas / methanol dual-fuel engine according to any one of claims 1-9.

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