JP2015048833A - Engine, engine drive type heat pump device, and heat value estimation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate a heat value of fuel gas with a relatively simple constitution.SOLUTION: An engine includes heat value estimation means 53 that in a state where valve opening adjustment means 52 adjusts the opening of a fuel flow rate adjustment valve 14 within an operable opening of an engine 60 in a minimum heat value fuel gas supply state where fuel gas G having an allowable minimum heat value of the engine 60 as a heat value is supplied, estimates the heat value of the fuel gas G on the basis of a change pattern of an engine rotational speed measured by rotational speed measurement means 26 right after the engine 60 is activated with no-load.

Description

  The present invention includes a combustion chamber for burning a mixed gas of fuel gas and combustion air, a fuel flow rate adjusting valve for adjusting a flow rate of the fuel gas supplied to the combustion chamber, and an opening degree of the fuel flow rate adjusting valve The present invention relates to an engine provided with a valve opening adjusting means for adjusting the engine speed, a rotational speed measuring means for measuring the engine rotational speed, an engine-driven heat pump device driven by the engine, and a calorific value estimation method.

As the fuel gas supplied to the engine, natural gas containing flammable gas such as ethane, propane, butane and the like, which is mainly composed of methane, may be used. Such natural gas may have a different composition when its production area is different, and therefore its calorific value may be different.
Furthermore, today, biogas produced using technology such as methane fermentation is sometimes used as fuel gas. In general, biogas has a lower calorific value than city gas with adjusted heat. Therefore, when biogas as fuel gas supplied to the engine is considered, the amount of generated heat is not constant and may change.
For the reason described above, in an engine using natural gas as a fuel gas whose calorific value changes due to composition variation, in order to estimate the calorific value well, a measurement engine is provided separately from the main engine. The fuel gas same as that of the main engine is supplied to the measurement engine, and when the measurement engine is operated with no load, the engine rotation speed is monitored to estimate the calorific value of the fuel gas. It is known (see Patent Document 1).

JP 2005-226621 A

However, in the technique disclosed in Patent Document 1 described above, in order to estimate the calorific value of the fuel gas, a measurement engine must be provided in addition to the main engine. There was a problem that became larger. In addition, in a system including a normal single engine, the technique described in Patent Document 1 cannot be adopted.
Further, when the calorific value of the fuel gas changes within a relatively small range, for example, 40 MJ / Nm ^{3 to} 46 MJ / Nm ³ , such a calorific value change is reflected in the engine speed during normal operation. In some cases, it is difficult to read the change in the heat generation amount from the change in the rotation speed of the engine.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to be able to estimate the heat generation amount of the fuel gas with a relatively simple configuration, and to follow the operation state of the engine to the estimated heat generation amount. It is in the point which provides the engine which can be made to run, the engine drive type heat pump apparatus provided with the said engine, and the calorific value estimation method of fuel gas.

The engine to achieve the above purpose is
A fuel flow control valve for adjusting the flow rate of the fuel gas;
A valve opening adjusting means for adjusting the opening of the fuel flow rate adjusting valve;
An engine provided with a rotational speed measuring means for measuring the rotational speed of the engine, characterized in that the valve opening adjusting means is a minimum amount of heat to which a minimum amount of fuel gas allowed by the engine is supplied as a calorific value. In the state where the opening of the fuel flow rate adjustment valve is adjusted to the opening at which the engine can be operated in the fuel gas supply state,
There is a calorific value estimating means for estimating the calorific value of the fuel gas based on a change pattern of the engine rotational speed measured by the rotational speed measuring means immediately after starting the engine with no load. .

The method of estimating the calorific value of the fuel gas to achieve the above purpose is as follows:
A fuel flow control valve for adjusting the flow rate of the fuel gas;
A valve opening adjusting means for adjusting the opening of the fuel flow rate adjusting valve;
A method for estimating the amount of heat generated by a fuel gas by an engine provided with a rotational speed measuring means for measuring an engine rotational speed, the characteristic configuration of which is as follows:
The opening degree of the fuel flow rate adjusting valve is set to the opening degree at which the engine can be operated in the minimum calorific fuel gas supply state in which the engine is allowed to supply the lowest calorie fuel gas that is allowed by the engine as the calorific value. An opening adjustment process for adjusting
After the opening degree adjusting step, the heat generation amount estimation for estimating the heat generation amount of the fuel gas based on the change pattern of the engine rotational speed measured by the rotational speed measuring means immediately after starting the engine with no load. And a process.

The engine rotation speed change pattern immediately after starting the engine with no load shows a relatively large change compared to the engine rotation speed change pattern during normal operation after a predetermined time has elapsed since startup. Moreover, according to the study by the inventors, as will be described later, at this timing, the change pattern of the engine rotation speed depends on the heat generation amount of the supplied fuel gas.
The above-described characteristic configuration pays attention to this point, and the heat generation amount of the fuel gas can be estimated based on a change pattern of the engine rotation speed immediately after the engine start showing a relatively large change. Therefore, it is difficult to read from the change pattern of the engine rotation speed during normal operation in the steady stable state, and the heat generation amount of the fuel gas is estimated with the heat generation amount appropriately reflecting the heat generation amount of the fuel gas. be able to.
Here, as a physical quantity that can represent the engine rotation speed change pattern, as will be described later, the maximum value of the engine rotation speed, the time to reach the maximum value, and the rate of increase in the rotation speed at the time of startup In addition, the shape of the change pattern itself is a physical quantity that depends on the amount of heat generated.
Further, in the above characteristic configuration, the engine measures the amount of heat generated by the fuel gas at the time of start-up, and can perform normal load operation during other operations. Therefore, the engine for measurement is not provided. With a simple configuration, it is possible to estimate the calorific value of the fuel gas and to operate the engine based on the estimation result.

Further features of the engine of the present invention are as follows:
The calorific value estimating means estimates the calorific value of the fuel gas based on the maximum value of the engine rotational speed that appears at the time of overshoot measured by the rotational speed measuring means immediately after starting without load. In the point.

  According to the above characteristic configuration, the heat generation amount estimation means is the maximum value of the engine rotation speed when the engine rotation speed is overshot immediately after starting the engine with no load, that is, the engine for each heat generation amount of the fuel gas. Since the heat generation amount of the fuel gas is estimated based on the maximum value of the engine rotation speed at which the difference in the rotation speed appears relatively clearly, the accuracy of the heat generation amount estimation can be further increased.

Further features of the engine of the present invention are as follows:
The heat generation amount estimation means is configured to estimate that the heat generation amount of the fuel gas is larger as the maximum value of the engine rotation speed is larger.

The greater the calorific value of the fuel gas, the greater the energy when the air-fuel mixture containing the fuel gas expands in the engine. When the engine is unloaded, the greater the energy, the faster the engine speed increases. The maximum value of the rotation speed increases.
Therefore, in the present invention, it can be estimated that the larger the maximum value of the engine rotation speed, the greater the calorific value of the fuel gas.

Further features of the engine of the present invention are as follows:
For each calorific value of the fuel gas whose calorific value is known, a storage unit is provided for storing a correspondence relationship between the excess air ratio and the opening of the fuel flow control valve,
Based on the calorific value of the fuel gas estimated by the calorific value estimation means and the target excess air ratio determined separately, the opening degree of the fuel flow rate adjustment valve is determined from the correspondence stored in the storage unit. It is in the point provided with the opening degree change means which changes.

Usually, the engine has an excess air ratio stored in the storage unit and a fuel flow rate adjustment valve so that the excess air ratio (actual air fuel ratio / theoretical air fuel ratio) of the air-fuel mixture supplied to the combustion chamber becomes the target excess air ratio. The opening degree of the fuel flow rate adjustment valve is adjusted based on the correspondence relationship with the opening degree.
The correspondence relationship is different for each calorific value of the fuel gas. Specifically, the larger the calorific value of the fuel gas, the smaller the opening of the fuel flow rate adjustment valve with respect to a predetermined excess air ratio. It will have.
Therefore, in the above-described characteristic configuration, for each calorific value of the fuel gas whose calorific value is known, the correspondence relationship is stored in the storage unit, and the calorific value of the fuel gas estimated by the calorific value estimating means is stored. Every time the amount changes, the valve opening changing means adjusts the fuel flow rate from the correspondence stored in the storage unit based on the estimated heat generation amount of the fuel gas and the separately determined target excess air ratio. By adjusting the opening of the valve, it is possible to realize an engine that can be operated while appropriately following the change in the calorific value of the fuel gas.

  The characteristic configuration of the engine-driven heat pump device for achieving the above object is that a compressor driven by the shaft output of the engine is provided.

  According to the above characteristic configuration, since the compressor of the heat pump device is driven by the engine that is operated following the change in the calorific value of the fuel gas appropriately, the calorific value of the fuel gas is also controlled in the operating state of the heat pump device. It is possible to drive stably by properly following the change of the vehicle.

Schematic configuration diagram of an engine-driven heat pump device according to the present invention The graph which shows the change pattern of the engine speed at the time of engine starting Flow diagram related to estimation of the calorific value of fuel gas and operation control based on the estimated calorific value

The engine 60 of the present invention, the engine-driven heat pump apparatus 100 using the engine 60 as a drive source, and the method for estimating the amount of heat generated by the fuel gas G by the engine 60 can be configured to calculate the amount of heat generated by the fuel gas G with a relatively simple configuration. The present invention relates to an engine that can be estimated and that can freely adjust the operation state of the engine 60 to an appropriate one based on the estimated calorific value.
Hereinafter, those configurations will be described in order.

  As shown in FIG. 1, the engine 60 of the present invention includes a combustion chamber 20 that burns an air-fuel mixture of a fuel gas G guided from a fuel flow path 13 and combustion air A guided from an air supply path 10, and the combustion An exhaust passage 31 is provided for guiding the exhaust gas E after the mixed gas is combusted in the chamber 20 to the outside.

A fuel flow path 13 provided with a fuel flow rate adjusting valve 14 that allows the fuel gas G to flow and adjusts the flow rate of the fuel gas G through the supply air path 10 is a combustion air A that flows through the air supply path 10. The fuel gas G flowing through the fuel flow path 13 in a state of maintaining a constant flow rate ratio with respect to the flow rate is connected via a venturi mixer 11 that mixes the combustion air A in the air supply path 10.
The air supply path 10 includes a throttle valve 12 that adjusts the flow rate of the air-fuel mixture on the downstream side of the venturi mixer 11, and is connected to the combustion chamber 20 via the air supply valve 15 on the downstream side of the throttle valve 12. .

The combustion chamber 20 includes a hollow cylindrical cylinder 25 and an upper surface of a piston 22 that can slide inside the cylinder 25. The piston 22 is provided with a connecting rod 23 that transmits the sliding movement in the cylinder 25 to the crankshaft 24 of the engine 60.
A cylinder head that is an upper surface of the cylinder 25 is provided with an ignition plug 21 that ignites an air-fuel mixture of the fuel gas G supplied to the combustion chamber 20 and the combustion air A, and the ignition plug 21 is compressed. The air-fuel mixture is combusted and expanded in such a manner that the air-fuel mixture is ignited, and the piston 22 is slid in the cylinder 25.

  The crankshaft 24 is provided with a crank angle sensor 26 (an example of a rotational speed measuring means). The crank angle sensor 26 measures the engine rotational speed by measuring the rotational angle of the crankshaft 24. Yes.

The crankshaft 24 of the engine 60 is connected to the rotating shaft of the compressor 40 of the heat pump apparatus 100 by a connecting member (not shown), and the compressor 40 is driven by the shaft output of the engine 60.
The engine-driven heat pump apparatus 100 using the engine 60 as a drive source radiates heat to the refrigerant circuit C that circulates the refrigerant L, the compressor 40 that compresses the refrigerant L, and the refrigerant L that is compressed and heated by the compressor 40. A condenser 41 to be expanded, an expansion valve 42 for expanding the refrigerant L after passing through the condenser 41, and an evaporator 43 for absorbing heat to the refrigerant L expanded and cooled by the expansion valve 42 are provided in the order of description. Yes.

The engine 60 and the engine-driven heat pump apparatus 100 of the present invention are configured as described above, but the fuel gas G supplied as fuel includes hydrocarbon gases such as methane, ethane, butane, propane, and the like. The natural gas is a natural gas, and the composition of the hydrocarbon gas contained in the natural gas varies due to a difference in the production area. Therefore, the calorific value of the natural gas may vary within a predetermined range. In this example, the range of change in the calorific value of the fuel gas changes from a minimum calorific value of 40 MJ / Nm ³ to a maximum calorific value of 46 MJ / Nm ³ with a variation range that is not allowed in conventional city gas. I am expecting. For this reason, even if the change range of the calorific value of the fuel gas G increases, the engine 60 realizes an appropriate operation following the change of the calorific value.
Therefore, in the engine 60 and the engine-driven heat pump apparatus 100 of the present invention, first, the heat generation amount of the fuel gas G is estimated by the following method.

[Estimation of calorific value of fuel gas]
In the engine 60 and the engine-driven heat pump apparatus 100 of the present invention, in order to estimate the heat generation amount of the fuel gas G, the heat generation amount of the fuel gas G can be allowed as the supply gas by the valve opening degree adjusting means 52. The crank immediately after the engine is started with no load in a state where the opening of the fuel flow rate adjustment valve 14 is adjusted so that the engine can be operated even with a minimum heat generation amount (specifically, 40 MJ / Nm ³ ). A calorific value estimating means 53 for estimating the calorific value of the fuel gas G is provided based on the engine rotational speed change pattern measured by the angle sensor 26 (an example of the rotational speed measuring means).

In further explanation, the engine rotation speed immediately after starting without load shows a change pattern that overshoots within a few seconds immediately after starting, as shown in FIG. The engine rotation speed during the overshoot has a characteristic that the reached value increases as the calorific value of the fuel gas G increases.
In particular, as can be seen from FIG. 2 (a), during the overshoot, the amount of change in the engine rotation speed is large, so the difference in the maximum value of the engine rotation speed according to the difference in the heat generation amount of the fuel gas G is also large. Therefore, it is easy to detect a change in the heat generation amount.
Therefore, in the present invention, for example, for each calorific value of the fuel gas G, the maximum value reached by the engine speed at the time of overshoot is stored in the storage unit 51 in advance, and the calorific value estimating means 53 is The amount of heat generated by the fuel gas G is estimated by comparing the maximum value reached by the engine speed at the time of overshooting with the maximum value of the engine speed stored in the storage unit 51.

  FIG. 2B shows a change pattern of the engine speed when the opening degree of the throttle valve 12 is set to the closed side as compared with the case of FIG. Compared with the engine rotation speed change pattern of FIG. 2A with a large opening, the engine rotation speed change pattern of FIG. Until the predetermined time elapses (up to 9 seconds in FIG. 2B), that is, at the time of overshoot immediately after the start of the engine 60, the maximum value at which the engine speed reaches the higher the amount of heat generated by the fuel gas G is. It is getting bigger. Thus, even when the throttle valve 12 is throttled to a certain extent, it can be seen that the amount of heat generated by the fuel gas G can be appropriately estimated by using the engine speed at the time of overshoot immediately after the engine 60 is started. .

  As for the specific estimation of the calorific value of the fuel gas G, as previously indicated, the storage unit 51 previously stores the change pattern of the engine speed when the fuel gas G whose calorific value is known is supplied. And the change pattern of the engine rotation speed when the fuel gas G as the heat generation amount estimation target is supplied is compared with the change pattern of the engine rotation speed stored in the storage unit 51, thereby generating the heat generation amount estimation target. The calorific value of the fuel gas G can be estimated.

[Adjustment of fuel flow adjustment valve opening based on estimated heat generation]
As described above, the calorific value of the changing fuel gas G is appropriately estimated. However, in the present invention, the fuel flow rate is determined based on the calorific value of the fuel gas G thus estimated. The opening degree of the adjustment valve 14 is adjusted so as to realize a preferable operating state of the engine, and the flow rate of the supplied fuel is adjusted so as to follow the heat generation amount of the fuel gas G.
When the explanation is added, the storage unit 51 determines the excess air ratio (actual air fuel ratio / theoretical air fuel ratio) of the air-fuel mixture supplied to the combustion chamber and the fuel flow rate for each heat generation amount of the fuel gas G whose heat generation amount is known. The correspondence relationship with the opening degree of the regulating valve is stored, and the correspondence relationship stored in the storage unit 51 based on the heat generation amount estimated by the heat generation amount estimation means 53 and the target air excess rate determined separately. The valve opening degree changing means 54 for changing the opening degree of the fuel flow rate adjusting valve 14 by the valve opening degree adjusting means is provided.

That is, in the present invention, the correspondence relationship between the excess air ratio and the opening of the fuel flow rate adjustment valve 14 is stored for each calorific value of the fuel gas G whose calorific value is known. When the calorific value of the fuel gas G estimated by the estimating means 53 has changed, it is stored in the storage unit 51 based on the calorific value of the fuel gas G after the change and a target excess air ratio determined separately. Thus, the opening degree of the fuel flow rate adjustment valve 14 is controlled.
Thereby, even if the calorific value of the fuel gas G changes, the excess air ratio of the mixture of the fuel gas G and the combustion air A guided to the combustion chamber 20 is set to the target excess air ratio. The opening degree of the fuel flow rate adjustment valve 14 is controlled.

[Control flow]
Next, the flow relating to the estimation of the calorific value of the fuel gas G in the present invention and the control of the opening of the fuel flow control valve 14 so as to follow the estimated calorific value will be described based on FIG.

In the present invention, the calorific value of the fuel gas G may change from the minimum calorific value (40 MJ / Nm ³ ) to the maximum calorific value (46 MJ / Nm ³ ). An opening adjustment step for adjusting the opening of the fuel flow rate adjustment valve 14 to the open side is performed so that the engine 60 can be started even with the amount (40 MJ / Nm ³ ), and the ignition timing is set to the retard side ( # 01).
In the present invention, the target rotational speed at startup of the engine 60 at startup is set to 1300 min ⁻¹ , the excess air ratio is set to 1.3, and the ignition timing is set to 20 degrees (BTDC).

Next, the engine 60 is started (# 02).
Based on the engine rotation speed change pattern, which is the measurement result of the crank angle sensor 26 immediately after the engine 60 is started, that is, the maximum value of the engine rotation speed at the time of overshoot, A heat generation amount estimation step for estimating the heat generation amount is executed (# 03).
Specifically, the heat generation amount of the fuel gas G is estimated based on the correspondence relationship that the heat generation amount of the fuel gas G increases as the maximum value of the change pattern of the engine rotation speed during overshoot increases.

  When the estimated heat value of the fuel gas G is different from the currently set heat value of the fuel gas G (# 04), in order to realize a suitable engine operating state with the estimated fuel gas G, The opening degree of the fuel flow control valve 14 is changed (# 05).

That is, it is stored in the storage unit 51 based on the estimated calorific value of the fuel gas G and a target excess air ratio (for example, 1.5) that is separately determined for realizing a preferable operating state of the engine. Therefore, the opening degree of the fuel flow rate adjustment valve 14 is changed.
In other words, the excess air ratio is set to a desired value with the estimated calorific value of the fuel gas G by changing the opening of the fuel flow control valve 14.

  On the other hand, when the estimated calorific value of the fuel gas G matches the calorific value of the fuel gas G that is currently set (# 04), the current opening of the fuel flow rate adjusting valve 14 is maintained.

[Another embodiment]
(1) In the above-described embodiment, the heat generation amount of the fuel gas G is estimated based on the maximum value of the engine rotation speed that appears at the time of overshoot measured by the crank angle sensor 26 immediately after starting without load. did.
As another estimation method, estimation may be performed based on the shape of a graph obtained by plotting the engine rotation speed measured by the crank angle sensor 26 with time immediately after starting without load.
As another estimation method, the heat generation amount is calculated based on the time from immediately after starting without load until the engine rotation speed that appears at the time of overshoot measured by the crank angle sensor 26 reaches the maximum value. It may be estimated.

  The engine, the engine-driven heat pump device, and the fuel gas heat generation amount estimation method according to the present invention can estimate the heat generation amount of the fuel gas with a relatively simple configuration, and the engine operation can be performed with the estimated heat generation amount. The present invention can be effectively used as an engine capable of following the state, and an engine-driven heat pump device including the engine.

14: Fuel flow rate adjusting valve 20: Combustion chamber 31: Exhaust passage 32: Oxygen sensor 40: Compressor 50: Engine 51: Storage unit 52: Valve opening adjusting means 53: Heat generation amount estimating means 54: Valve opening changing means 100 : Engine-driven heat pump device A: Combustion air C: Refrigerant circuit E: Exhaust gas G: Fuel gas L: Refrigerant

Claims (6)

A fuel flow control valve for adjusting the flow rate of the fuel gas;
A valve opening adjusting means for adjusting the opening of the fuel flow rate adjusting valve;
An engine having a rotational speed measuring means for measuring the engine rotational speed,
The opening degree of the fuel flow rate adjusting valve is set to an opening degree at which the engine can be operated in a minimum calorific fuel gas supply state in which the engine is allowed to supply a fuel gas having a minimum calorific value that the engine can accept as a calorific value. In the state of adjusting
An engine provided with a calorific value estimating means for estimating a calorific value of the fuel gas based on a change pattern of the engine rotational speed measured by the rotational speed measuring means immediately after starting the engine with no load.   The calorific value estimating means estimates the calorific value of the fuel gas based on the maximum value of the engine rotational speed that appears at the time of overshoot measured by the rotational speed measuring means immediately after starting without load. The engine according to claim 1.   The engine according to claim 2, wherein the heat generation amount estimation means estimates that the heat generation amount of the fuel gas is larger as the maximum value of the engine rotation speed is larger. For each calorific value of the fuel gas whose calorific value is known, a storage unit is provided for storing a correspondence relationship between the excess air ratio and the opening of the fuel flow control valve,
Based on the calorific value of the fuel gas estimated by the calorific value estimation means and the target excess air ratio determined separately, the opening degree of the fuel flow rate adjustment valve is determined from the correspondence stored in the storage unit. The engine according to any one of claims 1 to 3, further comprising an opening changing means for changing the angle.   An engine-driven heat pump device comprising a compressor that is driven by the shaft output of the engine according to any one of claims 1 to 4. A fuel flow control valve for adjusting the flow rate of the fuel gas;
A valve opening adjusting means for adjusting the opening of the fuel flow rate adjusting valve;
A method for estimating the amount of heat generated by a fuel gas by an engine having a rotational speed measuring means for measuring an engine rotational speed,
The opening degree of the fuel flow rate adjusting valve is set to the opening degree at which the engine can be operated in the minimum calorific fuel gas supply state in which the engine is allowed to supply the lowest calorie fuel gas that is allowed by the engine as the calorific value. An opening adjustment process for adjusting
After the opening degree adjusting step, the heat generation amount estimation for estimating the heat generation amount of the fuel gas based on the change pattern of the engine rotational speed measured by the rotational speed measuring means immediately after starting the engine with no load. And a calorific value estimation method for the fuel gas.

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