JPH0442536B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an output control device for a Stirling engine, and more particularly, to an output control device for a Stirling engine, and more particularly, to an output control device for controlling the output by the pressure of a working medium in a working space. This invention relates to an output control device for a Stirling engine.

(Prior Art) The output of a Stirling engine can be controlled by the pressure of the working medium in the working space, and when it is desired to obtain a high output, the pressure is increased, and when it is desired to reduce the output, the pressure is decreased.

However, when the pressure is increased, if the working medium is continuously supplied throughout the entire operating cycle, the engine output temporarily decreases in the initial stage. This phenomenon is particularly noticeable when the pressure is rapidly increased from low speed and low output, and the reason is that the compression work increases due to the supply of working medium even when the cycle is in the compression process.

In order to prevent this initial output drop, conventional
-69441, the distributor intended to supply the working medium mainly when the pressure in the working space is near the maximum cycle pressure, as shown in Figure 2. It is used. Figure 1 shows
This figure shows the configuration of an output control device using this distributor in a 4-cylinder Stirling engine, where 1 is a working medium reservoir, and 2, 3, 4, and 5 are first, second, third, and fourth working fluid reservoirs. Space, 6 to 17 are check valves, 18 is a pressure increase valve, 19 is a pressure reduction valve, 20 is a compressor, 21 is a main supply conduit, 22 is a distributor, and 23 is a conduit. The distributor 22 closes the main supply conduit 21 and the conduit 23 when the pressure in the working space is relatively low, and supplies medium when the working space is near the maximum cycle pressure, but the pressure in the working space is still present. When the pressure exceeds this value, the main supply conduit 21 and the conduit 23, which were closed at low pressure, are brought into communication, and also have the function of supplying medium throughout the entire operating cycle.

(Problem to be Solved by the Invention) However, the above-mentioned distributor needs to seal the high-pressure working medium without lubrication while rotating synchronously with the engine, but it is difficult to seal the high-pressure working medium without lubrication. There is also a problem with durability. In addition, mounting locations are limited by the engine for transmitting the rotation of the engine, and there are many fitting parts, making the mechanism and piping complicated, and the cost is high.

Incidentally, as shown in FIGS. 3 and 4, the initial output reduction amount upon pressure increase is determined by the engine speed and the flow rate of the working medium supplied to the working space. That is, the higher the engine speed and the lower the flow rate of the supplied medium, the smaller the amount of initial output (torque) decrease during pressure increase, and becomes negligible after reaching a certain range. Figures 3 to 5 show the range of rotational speed and supply flow rate in which the initial output decreases.

Therefore, the present invention provides an output control device for the Stirling engine that can control the output at the initial stage of pressure increase without reducing the durability of the device, complicating the configuration, increasing cost, and without causing restrictions on the mounting location. The technical challenge is to prevent this decline.

[Structure of the invention]

(Means for solving the problem) The means taken to solve the above technical problem is that the output control device an engine rotation speed sensor that detects the engine rotation speed, a pressure sensor that detects the pressure of the working medium in the working space, a throttle opening sensor that detects the degree of pressure increase request, and a The supply flow rate of the working medium supplied to the working space is calculated according to the signals from the valve mechanism, the throttle opening sensor, and the pressure sensor, which makes the flow rate of the supplied working medium variable, and the calculated supply flow rate is Set the engine rotation speed at which the initial output of the engine does not decrease due to the supply flow rate being supplied into the working space,
It consists of a calculator that compares this set engine speed and the engine speed detected by the engine speed sensor,
The purpose is to limit the flow rate of the working medium supplied to the working space by using variable flow rate operation of the valve mechanism so that the initial output of the engine does not decrease.

(effect) The above means works as follows.

When you want to increase the output of the engine, when the degree of pressure increase request is detected by the throttle opening sensor, the flow rate of the working medium to be supplied to the working space is calculated by a calculator based on the signals from the throttle opening sensor and the pressure sensor. Calculated by The computing unit sets a rotation speed at which the initial output does not decrease when the calculated flow rate is supplied into the working space, and compares this set rotation speed with a signal from the engine rotation speed sensor. If the engine speed is lower than the set speed,
The computing unit controls the valve mechanism so that the flow rate supplied to the working space is reduced, and the flow rate of the working medium supplied to the working space during pressure increase is reduced to a flow rate range that does not cause an initial output drop.

When the engine speed is higher than the set rotation speed, the computing unit controls the valve mechanism to increase the flow rate supplied to the working space, and increases the flow rate of the working medium supplied to the working space when pressure is increased; Increase output.

(Example) Hereinafter, an example of an output control device for a Stirling engine according to the present invention will be described based on the drawings.

FIG. 6 shows an embodiment in which the present invention is applied to a four-cylinder Stirling engine.
Reference numeral 1 denotes a working medium reservoir, and the reservoir 101 is connected to one end of a pressure increase valve 130 through a conduit 114. The other end of the pressure increase valve 130 communicates with one end of an orifice 133 through a conduit 115.
The other end of 3 is connected to conduits 116 to 120 and check valve 10.
It communicates with the working spaces 102-105 via 6-109.

At both ends of the orifice 133, conduits 128, 1
A supply flow rate control valve 134, which is a valve mechanism in the present invention, is connected in parallel to the orifice 133 by 29. The working spaces 102 to 105 are further connected to one end of a pressure reducing valve 132 by check valves 110 to 113 and conduits 121 to 125, and the other end of the pressure reducing valve 132 is connected to the compressor 13 by a conduit 126.
It communicates with the intake port No.5. The outlet of compressor 135 communicates with reservoir 101 by conduit 127 . Note that at least one of the working spaces 102 to 105 is provided with a pressure sensor 136 that detects the pressure of the working medium in the working space to detect a typical pressure in the working space. The pressure increase valve 130 also includes a throttle opening sensor 131 that detects its opening.
Although not shown in FIG. 6, the Stirling engine is provided with an engine speed sensor for detecting the engine speed.

FIG. 7 shows the supply flow rate control valve 13 in FIG.
4 shows a control mechanism including an arithmetic unit in the present invention that controls the driving of the motor. The calculator includes a flow calculator 138 that calculates the flow rate of the working medium to be supplied to the working spaces 102 to 105 according to signals from the pressure sensor 136 and the throttle opening sensor 131.
and a limit rotation speed setting device 139 that sets a limit rotation speed at which the initial output does not decrease when the flow rate calculated by the flow rate calculator 138 is supplied into the working spaces 102 to 105; A comparator 140 that compares the set value by the setting device 139 and the rotation speed detected by the engine rotation speed sensor 137.
The drive current to the supply flow rate control valve drive circuit 141 is controlled based on the judgment result of the comparator 140.

The operation of this embodiment having the above configuration will be explained based on FIGS. 6 and 7.

When the engine is in steady operation, the pressure increase valve 130 and the pressure reduction valve 132 remain closed, and the supply flow control valve 1
34 is also closed. Thus, when it is desired to increase the output of the engine, the pressure increase valve 130 is opened. Pressure increase valve 13
0, the opening degree, and the pressure in the working spaces 102 to 105 determine the flow rate of the medium flowing through the pressure increase valve 130. Therefore,
Throttle opening sensor 131 and pressure sensor 136
According to the signal, the flow rate calculator 138 controls the pressure increase valve 13.
Calculate the flow rate of the medium flowing through the engine speed sensor 137, set the rotation speed at which no initial output decrease occurs (rotation speed R1 for the flow rate Q1 in FIG. 5) using the limit rotation speed setting device 139, The comparator 140 compares the signal with the signal of . When the engine speed is below this set point, the supply flow control valve 134 remains closed.

At this time, the working medium that has passed through the pressure increase valve 130 is
The orifice 133 restricts the flow rate to a range where no initial output drop occurs. Therefore, the working medium supplied by the orifice 133 allows the engine to maintain its initial output without decreasing its output.
Its rotational speed increases, its rotational speed reaches the set value,
Thereafter, the supply flow rate control valve drive circuit 141 and the supply flow rate control valve 134 are opened, and the working medium flowing through the pressure increase valve 130 is not restricted by the flow rate, and the working space 102 is
~105. When the engine speed is high from the beginning of pressure increase, the supply flow rate control valve 134 is opened from the beginning.

By controlling the supply flow rate of the working medium as described above, it is possible to prevent the initial output from decreasing in response to a request for an increase in output under all conditions of the engine.

8 to 10 show modified embodiments of the present invention, and FIG. 8 shows the pressure increase valve 130 in FIG. 6.
The orifice 133 and the supply flow control valve 134 are replaced with one flow control valve 142a, and the throttle opening sensor 143, which is provided separately from the flow control valve 142a and detects the degree of pressure increase request, is replaced with the throttle opening sensor 143 shown in FIG. It replaces the opening sensor 131.

In FIG. 8, the throttle opening sensor 143
The pressure increase request signal from the engine, the rotation speed signal from the engine rotation speed sensor 137, and the pressure signal from the pressure sensor 136 in the working space are input to a computing unit 144, and the control mechanism including the computing unit 144 is shown in FIG. , the computing unit 144 operates the flow computing unit 1 according to the signals from the pressure sensor 136 and the throttle opening sensor 143.
38 calculates the flow rate of the working medium to be supplied to the working space, and determines the limit rotation speed at which the initial output does not decrease when the flow rate calculated by the flow rate calculator 138 is supplied into the working space. Set with the limit rotation speed setting device 139, and the limit rotation speed setting device 1
A comparator 140 compares the set value set by the engine 39 with the engine speed detected by the engine speed sensor 137. When the engine speed is lower than the set value, the flow control valve drive circuit 141 activates the throttle opening sensor 14.
The opening degree of the flow rate control valve 142a is adjusted so that the flow rate does not cause a decrease in initial output regardless of the pressure increase request signal from 3. Thereafter, when the rotational speed increases, the flow rate control valve drive circuit 141 adjusts the flow rate control valve 142a so that the flow rate matches the pressure increase request. Other configurations and operations are the same as those of the embodiment shown in FIG. 6, so detailed explanations will be omitted.

Further, in the modified embodiment shown in FIG. 9, the flow rate control valve 142a of FIG.
It is replaced by c. In this example,
A flow control valve drive circuit 141 shown in FIG. 10 adjusts the number of solenoid valves that are in an open state, and controls the flow rate of the working medium during pressure increase. Since the method of this control can be easily understood from the explanation of the embodiments shown in FIGS. 6 and 8 above, detailed explanation thereof will be omitted.

〔Effect of the invention〕

As explained above, according to the present invention, there is no rotating seal part, the device is excellent in reliability and durability, it is easy to keep the working medium supply circuit free of lubrication, and it is completely separate from the engine. It can also be installed in the following locations. Moreover, the mechanism is simple, so the cost is low.
Maintenance is also easy. Therefore, in the output control device for the Stirling engine, it is possible to reduce the output decrease at the initial stage of pressure increase without reducing the durability of the device, complicating the configuration, increasing cost, and without causing restrictions on the installation location. It becomes possible to prevent this.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the configuration of a typical Stirling engine output control device using a conventional device for preventing an initial output drop during pressure increase, and Figure 2 is an explanatory diagram showing the configuration of a typical Stirling engine output control device using a conventional device for preventing an initial output drop during pressure increase. A diagram showing the supply timing of the working medium, Fig. 3 is a diagram showing the relationship between the engine rotation speed and the amount of initial torque reduction when the working medium is continuously supplied over the entire fixed cycle of the Stirling engine, and Fig. 4 is a diagram showing the relationship between the engine speed and the amount of initial torque reduction. Similarly, FIG. 5 is a diagram showing the relationship between the supply flow rate and the amount of initial torque reduction, FIG. 5 is a diagram showing the range of the rotational speed at which the initial output decrease occurs and the supply flow rate of the working medium, and FIG. 6 is a diagram showing the Stirling engine according to the present invention. FIG. 7 is an explanatory diagram showing the configuration of an embodiment of the output control device shown in FIG. 6, FIG. 8 and FIG. FIG. 10 is an explanatory diagram showing the control mechanism of the modified embodiment shown in FIGS. 8 and 9. 101... Reservoir, 102-105... Operating space, 130... Pressure increase valve, 131... Throttle opening sensor, 133... Orifice, 134...
Supply flow control valve, 136...Pressure sensor, 137
...Engine speed sensor, 138...Flow rate calculator,
139...Limit rotation speed setter, 140...Comparator, 141...Supply flow rate control valve drive circuit (flow rate control valve drive circuit), 142a...Flow rate control valve, 14
2b, 142c... Solenoid valve.

Claims (1)

[Claims] 1. An output control device for a Stirling engine that controls output according to the pressure of a working medium in a working space, which comprises: an engine speed sensor that detects the engine speed; a pressure sensor that detects the pressure of the working medium in the space; a throttle opening sensor that detects the degree of pressure increase request; a valve mechanism that varies the flow rate of the working medium supplied to the working space when the pressure is increased; A supply flow rate of the working medium to be supplied to the working space is calculated according to signals from the throttle opening sensor and the pressure sensor, and the supply flow rate is supplied into the working space with respect to the calculated supply flow rate. an arithmetic unit configured to set an engine rotation speed at which the initial output of the engine does not decrease, and to compare this set engine rotation speed with the engine rotation speed detected by the engine rotation speed sensor; An output control device for a Stirling engine, characterized in that the flow rate of the working medium supplied to the working space is limited by variable flow rate operation of the valve mechanism so that the output does not decrease.