JP4760777B2 - External combustion engine - Google Patents

Description

  The present invention relates to an external combustion engine that displaces a liquid phase portion of a working medium by evaporation and condensation of the working medium, converts the displacement of the liquid phase portion of the working medium into mechanical energy, and outputs the mechanical energy.

  Conventionally, this type of external combustion engine, also called a liquid piston steam engine, encloses a working medium in a tubular container so as to be able to flow in a liquid state, and is in a liquid state at an evaporation section formed at one end of the container. A part of the working medium is heated and evaporated, the working medium vapor is cooled and condensed in the condensing part formed in the middle part of the container, and the working medium is operated by repeating evaporation and condensation alternately. The liquid phase portion of the medium is periodically displaced (so-called self-excited vibration), and the self-excited vibration of the liquid phase portion of the working medium is extracted as mechanical energy at the output unit (for example, Patent Documents). 1).

  That is, the liquid piston steam engine has a first stroke and a first stroke in which a part of the working medium in a liquid state is evaporated in the evaporation section and the liquid phase portion of the working medium is displaced from the evaporation section side toward the output section side. By repeating the second step of alternately condensing the vapor of the working medium generated in the above in the condensing unit and displacing the liquid phase portion of the working medium from the output unit side toward the evaporation unit side. The phase part is self-excited and oscillated as a liquid piston to obtain an output.

In this liquid piston steam engine, the internal pressure of the container rises by evaporation of the working medium in the first stroke, and the internal pressure of the container decreases by condensation of the working medium in the second stroke. Will vary.
JP 2004-84523 A

  By the way, Japanese Patent Application No. 2006-78802 (hereinafter referred to as a prior application example) proposes an improvement in performance (output and efficiency) of a liquid piston steam engine.

  In this prior application example, the performance of the liquid piston steam engine is highest when the average value of the internal pressure of the container is a predetermined ideal value (hereinafter referred to as the ideal average value), and the inside of the container In view of the fact that the ideal average value of pressure changes with the temperature fluctuation of the evaporation section, the average value of the internal pressure of the container can be adjusted as appropriate based on the temperature of the evaporation section.

  More specifically, an auxiliary container in which only a liquid and a gas or only a liquid are sealed is provided separately from the main container in which the working medium is sealed, and the auxiliary container is communicated with the main container through the throttle portion. . Then, the internal pressure of the auxiliary container is controlled by compressing or expanding the liquid and / or gas in the auxiliary container by the piston mechanism driven by the electric actuator, and as a result, the average value of the internal pressure of the main container is Adjust as appropriate.

  However, in the prior application example, the internal pressure of the main container is lower than the internal pressure of the auxiliary container in the first half of the second stroke, and the internal pressure of the main container is higher than the internal pressure of the auxiliary container in the second half of the second stroke. Therefore, the liquid in the auxiliary container flows into the auxiliary container in the first half of the second stroke and a part of the liquid phase portion of the working medium in the main container in the second half of the second stroke. Will flow into the auxiliary container.

  For this reason, when the volume of the liquid phase part of the working medium flowing into the auxiliary container from the main container during the second stroke is larger than the volume of the liquid flowing into the main container from the auxiliary container, Since the volume of the self-excited liquid piston is reduced, the liquid phase portion of the working medium is difficult to reach the evaporation section at the end of the second stroke.

  As a result, the working medium is insufficiently evaporated in the first stroke, and the performance of the liquid piston steam engine is degraded. In the worst case, the liquid phase portion of the working medium does not reach the evaporation section at the end of the second stroke, and the working medium is not evaporated in the first stroke. It will stop.

  In view of the above points, an object of the present invention is to prevent the self-excited vibration of the working medium from stopping due to the inflow of the working medium into the auxiliary container.

To achieve the above object, the present invention includes a tubular main container (11) in which a working medium (15) is encapsulated in a liquid state so as to be flowable.
An evaporation section (11d) that is formed at one end of the main container (11) and evaporates by heating a part of the working medium (15) in the main container (11);
A condensing part (11e) that is formed in a part of the main container (11) on the other end side of the evaporation part (11d) and cools and condenses the vapor of the working medium (15) evaporated in the evaporation part (11d). )When,
An output unit (12) that communicates with the other end of the main container (11), converts the displacement of the liquid phase portion of the working medium (15) into mechanical energy, and outputs the mechanical energy;
Auxiliary container (21) in which liquid (23) is sealed, communicating with a portion between main condenser (11) between condensing part (11e) and output part (12) via communication part (22),
Pressure adjusting means (26) for adjusting the internal pressure (P2) of the auxiliary container (21),
A first step of evaporating the working medium (15) by the evaporation section (11d) and displacing the liquid phase portion of the working medium (15) from the evaporation section (11d) side toward the output section (12) side; Secondly, the working medium (15) evaporated in the process is condensed in the condensing part (11e), and the liquid phase part of the working medium (15) is displaced from the output part (12) side toward the evaporating part (11d) side. In the external combustion engine that repeats the process alternately,
The volume of the liquid phase portion of the working medium (15) flowing into the auxiliary container (21) from the main container (11) and the auxiliary container (21) into the main container (11) during the second stroke. The flow coefficient (Cv) of the communication part (22) is set so that the difference from the volume of the liquid (23) to be reduced is smaller than the volume (Vh) of the evaporation part (11d).

  According to this, at the end of the second stroke, it is possible to avoid the liquid phase portion of the working medium (15) from reaching the evaporation section (11d), so that evaporation of the working medium in the first stroke can be maintained. it can. Therefore, the stop of the self-excited vibration of the working medium (15) can be prevented.

Specifically, the present invention includes an electric variable throttle mechanism (25) disposed in the communication portion (22),
Control means (27) for controlling the throttle opening of the variable throttle mechanism (25) so that the flow coefficient (Cv) satisfies Formula 1 according to claim 2,
The flow coefficient (Cv) is set by the variable throttle mechanism (25) and the control means (27).

  In the present invention, “the flow coefficient (Cv) satisfies Formula 1” does not mean that Formula 1 is strictly satisfied, but it also means that Formula 1 is approximately satisfied. .

Further, the present invention specifically includes a changing means (thermally connected to the evaporation section (11d) and deformed by heat transmitted from the evaporation section (11d) to change the flow path diameter of the communication section (22). 30, 31),
The change means (30, 31) reduces the flow path diameter of the communicating portion (22) when the temperature (T1) of the evaporating portion (11d) increases, and reduces the communicating portion (22) when the temperature (T1) of the evaporating portion (11d) decreases. 22) is configured to increase the flow path diameter,
The flow coefficient (Cv) may be set by the changing means (30, 31).

  Further, in the present invention, specifically, the communication portion (22) is formed so that the flow coefficient (Cv) satisfies Formula 2 according to claim 4.

  According to this, since the self-excited vibration of the working medium (15) can be satisfactorily maintained by a simple configuration with a constant flow coefficient (Cv), the cost can be reduced.

  In the present invention, “the flow coefficient (Cv) satisfies Expression 2” does not mean that expression 2 is strictly satisfied, but also that expression 2 is approximately satisfied. . Further, the “maximum temperature of the temperature (T1) of the evaporating part (11d)” in the present invention means the maximum temperature of the temperature (T1) of the evaporating part (11d) assumed under normal use conditions. It is.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram showing a schematic configuration of an external combustion engine (liquid piston steam engine) 10 according to the present embodiment, and the up and down arrows in FIG. 1 indicate the vertical direction in the installed state of the liquid piston steam engine 10. .

  The liquid piston steam engine 10 according to the present embodiment includes a main container 11 and a generator 12 that forms an output unit. The generator 12 houses a mover 14 in which a permanent magnet is embedded in a casing 13, and generates an electromotive force when the mover 14 is displaced by vibration.

  The main container 11 is a pressure container in which a working medium (water in this example) 15 is sealed so as to be able to flow in a liquid state. On the outer surface of the main container 11, a heater 16 that heats and evaporates a part of the working medium 15 in a liquid state inside the main container 11, and the working medium 15 that is heated and evaporated by the heater 16 is cooled. A cooler 17 to be condensed is disposed in contact.

  Although the heater 16 of this embodiment exchanges heat with a high-temperature gas (for example, exhaust gas from an automobile), the heater 16 may be constituted by an electric heater. In addition, cooling water circulates in the cooler 17 of the present embodiment. Although not shown, a radiator that dissipates heat taken from the steam of the working medium 15 by the cooling water is disposed in the circulating circuit of the cooling water.

  And the main container 11 is a pipe-shaped pressure container formed in the substantially U shape which has the 1st, 2nd linear parts 11b and 11c so that the bending part 11a may be located in the lowest part, A heater 16 and a cooler 17 are provided on the first straight line portion 11b on one end side in the horizontal direction (right side of the sheet) across the bent portion 11a so that the heater 16 is positioned above the cooler 17. .

  In this example, since the working medium 15 is water, the main container 11 is formed of stainless steel. However, the evaporation unit 11d that is a part of the main container 11 that contacts the heater 16 and evaporates the working medium 15. And the condensing part 11e which is a site | part which contacts the cooler 17 and condenses the working medium 15 may be formed with copper, aluminum, etc. excellent in thermal conductivity.

  The evaporation part 11d has a predetermined volume Vh. In FIG. 1, for convenience, the volume Vh of the evaporation part 11 d is indicated by a broken-line hatched area.

  Although illustration is omitted, in order to secure a space for the working medium 15 to evaporate, a predetermined volume of gas is sealed at the upper end portion of the first linear portion 11b. This gas may be, for example, air or pure vapor of the working medium 15.

  On the other hand, on the upper end portion of the second linear portion 11c on the other end side in the horizontal direction (left side in the drawing) across the bent portion 11a of the main container 11, a piston 18 that is displaced by receiving pressure from the working medium is attached to the cylinder portion 19. It is slidably arranged.

  The piston 18 is connected to the shaft 14a of the movable element 14, and an elastic means for generating an elastic force that presses the movable element 14 toward the piston 18 is formed on the opposite side of the piston 18 with the movable element 14 interposed therebetween. A coil spring 20 is provided.

  Next, a mechanism for adjusting the internal pressure (hereinafter referred to as main container internal pressure) P1 of the main container 11 will be described. The auxiliary container 21 communicates with the main container 11 via a tubular communication portion 22. . In this example, the auxiliary container 21 is disposed above the bent portion 11a.

  A liquid 23 and a gas 24 are sealed in the auxiliary container 21. In this example, the liquid 23 is water as in the working medium 13. It is preferable to use a gas that is sparingly soluble in the liquid 23 as the gas 24. In this example, helium that is sparingly soluble in water is used as the gas 24. Note that only the liquid 23 may be sealed in the auxiliary container 21.

  The auxiliary container 21 and the communication part 22 are desirably made of materials having excellent heat insulation properties. In this embodiment, the liquid 23 is water, and therefore the auxiliary container 21 and the communication part 22 are made of stainless steel.

  An electrical variable aperture mechanism 25 is disposed in the communication portion 22. The variable throttle mechanism 25, together with a control device 27 described later, constitutes a flow coefficient adjusting means for adjusting a flow coefficient Cv (details will be described later) of the communicating portion 22.

  The pressure adjusting means 26 for adjusting the internal pressure (hereinafter referred to as auxiliary container internal pressure) P2 of the auxiliary container 21 includes a pressure adjusting piston 26a and an electric actuator 26b.

  The pressure adjustment piston 26 a is arranged on the upper end side in the auxiliary container 21 so as to be slidable in the vertical direction. The electric actuator 26b is disposed above the auxiliary container 21 and drives the pressure adjusting piston 26a in the vertical direction.

  Next, the outline of the electronic control unit in the present embodiment will be described. The control device 27 is composed of a well-known microcomputer comprising a CPU, ROM, RAM and the like and its peripheral circuits. It corresponds to the means.

  In order to control the pressure adjusting means 26, the control device 27 includes a temperature sensor 28 for detecting the temperature of the evaporator 11d (hereinafter referred to as the evaporator temperature) T1 and a pressure sensor 29 for detecting the auxiliary container internal pressure P2. A detection signal is input from. The control device 27 controls the electric actuator 26b based on the detection signals from the sensors 28 and 29.

  Next, the operation in the above configuration will be described. When the heater 16 and the cooler 17 are operated, first, a first step of displacing the liquid phase portion of the working medium 15 toward the generator 12 side is performed. In the first step, the working medium 15 in the liquid state in the evaporation section 11d is heated and evaporated by the heater 16, and the vapor of the high-temperature and high-pressure working medium 15 is accumulated in the evaporation section 11d. The liquid level of the working medium 15 in the part 11b is pushed down.

  Then, the liquid phase part of the working medium 15 enclosed in the part closer to the generator 12 than the evaporation part 11d in the main container 11 is displaced from the evaporation part 11d side to the generator 12 side. The piston 18 is pushed up. At this time, the coil spring 20 is elastically compressed.

  When the liquid level of the working medium 15 falls to the condensing part 11e in the first linear part 11b and the vapor of the working medium 15 enters the condensing part 11e, the liquid phase part of the working medium 15 is directed toward the evaporation part 11d. A second stroke to be displaced is performed.

  In this second stroke, the vapor of the working medium 15 that has entered the condensing part 11e is cooled and condensed by the cooler 17, and the force that pushes down the liquid level of the working medium 15 in the first linear part 11b disappears.

  Then, the piston 18 on the generator 12 side that is once pushed up by the expansion of the steam of the working medium 15 is lowered by the elastic restoring force of the coil spring 20, and the piston 12 on the side of the generator 12 that is once pushed up by the expansion of the steam of the working medium 15 The piston 18 descends.

  For this reason, the liquid phase part of the working medium 15 is displaced from the generator 12 side to the evaporation part 11d side, and the liquid level of the working medium 15 rises to the evaporation part 11d in the first linear part 11b. The working medium 15 in the liquid state is heated and evaporated in the portion 11d.

  The first stroke and the second stroke are repeated until the operations of the heater 16 and the cooler 17 are stopped. During this time, the liquid phase portion of the working medium 15 in the main container 11 is periodically displaced (so-called self-propagation). Exciting vibration) causes the mover 14 of the generator 12 to move up and down.

  That is, by alternately and repeatedly performing evaporation and condensation of the working medium 15, the liquid phase portion of the working medium 15 self-excites and vibrates as a liquid piston, and the self-excited vibration of the liquid piston is extracted as an output. For this reason, the external combustion engine according to the present embodiment can also be called a liquid piston steam engine.

  FIG. 2 is a graph showing the relationship between the change in piston volume in the first and second strokes, and the pressure waveforms of the main container internal pressure P1 and the auxiliary container internal pressure P2. Here, the piston volume is a volume of a space surrounded by the main container 11, the cylinder portion 19, and the piston 18, and this piston volume fluctuates periodically as the piston 18 reciprocates.

  As can be seen from FIG. 2, the main container pressure P1 also periodically varies between the peak value P1p and the bottom value P1b in accordance with the periodic variation of the piston volume. On the other hand, the internal pressure P2 of the auxiliary container 21 is substantially constant.

  That is, since the variable throttle mechanism 25 is disposed in the communication part 22 and the flow path diameter of the communication part 22 is reduced, the auxiliary container internal pressure P2 is suppressed from following the periodic fluctuation of the main container internal pressure P1. The average value P1a of the main container internal pressure P1 is stabilized at a pressure substantially equal to the auxiliary container internal pressure P2.

  3A to 3C are PV diagrams for explaining the relationship between the peak value P1p of the main container internal pressure P1 and the performance (output and efficiency) of the liquid piston steam engine 10. The horizontal axis of this PV diagram is the piston volume described above.

  First, FIG. 3A shows an ideal state in which the performance (output and efficiency) of the liquid piston steam engine 10 is the highest. That is, as shown in FIG. 3A, the peak value P1p of the main container internal pressure P1 is lower than the saturated vapor pressure Ps of the working medium 15 at the evaporator temperature T1 and is as close as possible to the saturated vapor pressure Ps. (Hereinafter referred to as the ideal peak value), the liquid piston steam engine 10 has the largest work per cycle, and the performance of the liquid piston steam engine 10 is the highest. In addition, the average value P1a of the main container internal pressure P1 at this time is hereinafter referred to as an ideal average value.

  On the other hand, FIG. 3B shows a PV diagram when the peak value P1p is significantly lower than the saturated vapor pressure Ps. In this state, the work amount per cycle is small, and the performance of the liquid piston steam engine 10 is degraded.

  FIG. 3C shows a PV diagram when the peak value P1p is higher than the saturated vapor pressure Ps. In this state, since the peak value P1p is higher than the saturated vapor pressure Ps, a part of the vapor of the working medium 13 is condensed. For this reason, since negative work is performed, the performance of the liquid piston steam engine 10 is deteriorated.

  Therefore, in order to maximize the performance of the liquid piston steam engine 10, the peak value P1p of the main container internal pressure P1 should always be maintained at the ideal peak value.

  Here, it is known that the bottom value P1b of the main container internal pressure P1 is substantially equal to the atmospheric pressure. Therefore, when the peak value P1p of the main container internal pressure P1 increases, the average value P1a of the main container internal pressure P1 also increases, and when the peak value P1p of the main container internal pressure P1 decreases, the average value P1a of the main container internal pressure P1 also increases. Will be reduced.

  For this reason, if the average value P1a of the main container internal pressure P1 is always maintained at the ideal average value, the peak value P1p of the main container internal pressure P1 can be always maintained at the ideal peak value. The best performance can be obtained.

  However, when the temperature of the high-temperature gas that is the heat source of the heater 16 varies, the evaporator temperature T1 also varies. As a result, since the saturated vapor pressure Ps of the working medium 13 also varies, the ideal peak value also varies, and consequently the ideal average value also varies.

  Therefore, the liquid piston steam engine 10 according to the present embodiment always maintains the average value P1a of the main container internal pressure P1 at the ideal average value by adjusting the main container internal pressure P1 according to the fluctuation of the evaporation part temperature T1. Thus, the performance of the liquid piston steam engine 10 is maximized.

  More specifically, the average value P1a of the main container internal pressure P1 is always brought close to the ideal average value by bringing the average value P1a of the main container internal pressure P1 close to the target value P1A approximated to the ideal average value.

  FIG. 4 is a block diagram showing an outline of control of the main container internal pressure P1 in the present embodiment. First, based on the evaporation part temperature T1 and the vapor pressure curve of the working medium 15 stored in the control device 27 in advance, the saturated vapor pressure Ps of the working medium 15 at the evaporation part temperature T1 is calculated.

  Next, an average value between the saturated vapor pressure Ps of the working medium 15 and the atmospheric pressure (0.1 MPa) at the evaporation portion temperature T1 is calculated as the target value P1A, and this average value is set as the target value P1A.

  That is, as can be seen from FIG. 3A, the average value of the saturated vapor pressure Ps of the working medium 15 at the evaporation portion temperature T1 and the bottom value P1b in one cycle of the main container internal pressure P1 is an ideal average value. An approximate value.

  Further, it is known that the bottom value P1b in one cycle of the main container internal pressure P1 is substantially equal to the atmospheric pressure (0.1 MPa). For these reasons, the average value of the saturated vapor pressure Ps of the working medium 15 and the atmospheric pressure (0.1 MPa) at the evaporator temperature T1 is a value that approximates the ideal average value.

  Therefore, in this example, the average value of the saturated vapor pressure Ps of the working medium 15 and the atmospheric pressure (0.1 MPa) at the evaporator temperature T1 is set as the target value P1A. A value obtained by appropriately correcting the average value may be set as the target value P1A.

  When the auxiliary container internal pressure P2 is lower than the target value P1A, the electric actuator 26b pushes out the pressure adjusting piston 26a to reduce the volume of the auxiliary container 21. Thereby, the liquid 23 is compressed and the auxiliary container internal pressure P2 rises.

  On the other hand, when the auxiliary container internal pressure P2 is higher than the target value P1A, the volume of the auxiliary container 21 is decreased by retracting the pressure adjusting piston 26a. Thereby, the liquid 23 expand | swells and the auxiliary container internal pressure P2 falls.

  Then, the average value P1a of the main container internal pressure P1 changes following the auxiliary container internal pressure P2, and the average value P1a of the main container internal pressure P1 approaches the target value P1A. In other words, since the average value P1a of the main container internal pressure P1 approaches the ideal average value, the performance of the liquid piston steam engine 10 can be maximized.

  Incidentally, FIG. 5 is an enlarged cross-sectional view in the vicinity of the communication portion 22. In FIG. 5, the variable aperture mechanism 25 is not shown for the sake of illustration. When the main container internal pressure P1 is larger than the auxiliary container internal pressure P2, the liquid phase portion of the working medium 15 in the main container 11 flows into the auxiliary container 21 as shown by the arrow in FIG. Become.

  The volume flow rate Q of the liquid phase portion of the working medium 15 in the communication portion 22 at this time can be expressed as Q = Cv × (P1−P2). Here, Cv is a flow coefficient of the communication portion 22 and is a value determined from the shape of the communication portion 22 (flow path length, flow path diameter, etc.).

  Therefore, as the flow coefficient Cv of the communication part 22 increases, the volume flow rate Q of the liquid phase portion of the working medium 15 flowing from the main container 11 into the auxiliary container 21 increases. In this embodiment, the communication part 22 is used. Since the electric variable throttle mechanism 25 is disposed at the center, the flow coefficient Cv of the communication portion 22 can be arbitrarily set by adjusting the throttle opening of the variable throttle mechanism 25.

  On the other hand, FIG. 6 is a graph showing the relationship between the flow coefficient Cv of the communicating portion 22 and the efficiency of the liquid piston steam engine 10 when the peak value P1p of the main container internal pressure P1 and the auxiliary container internal pressure P2 are constant. . In addition, since the relationship between the flow coefficient Cv of the communication part 22 and the output of the liquid piston steam engine 10 is the same as that of FIG. 6, illustration is abbreviate | omitted.

  A point A in FIG. 6 is a state in which the flow coefficient Cv of the communication portion 22 is appropriately set. At this time, the PV diagram is as shown in FIG. Highest performance.

  On the other hand, point B in FIG. 6 is a state in which the flow coefficient Cv of the communicating portion 22 is too large. At this time, the PV diagram is as shown in FIG. 3B, and the performance of the liquid piston steam engine 10 is degraded. . This is due to the following reason.

  That is, as can be seen from FIG. 2, the main container internal pressure P1 is lower than the auxiliary container internal pressure P2 in the first half of the second stroke, and the main container internal pressure P1 is lower than the auxiliary container internal pressure P2 in the second half of the second stroke. Also grows.

  Therefore, the liquid 23 in the auxiliary container 21 flows into the main container 11 in the first half of the second stroke. Conversely, in the second half of the second stroke, the liquid phase portion of the working medium 15 in the main container 11 is in the auxiliary container 21. Will flow in.

  According to the study of the present inventor, the volume of the liquid phase portion of the working medium 15 that flows from the main container 11 into the auxiliary container 21 during the second stroke is the liquid that flows from the auxiliary container 21 into the main container 11. It is known that the volume of the liquid piston that self-excites in the main container 11 is reduced.

  Therefore, when the flow coefficient Cv of the communication portion 22 is too large, the amount of decrease in the liquid piston volume increases, and the liquid phase portion of the working medium 15 is reached at the end of the second stroke, that is, when the piston volume is reduced most. However, it becomes difficult to reach into the evaporation part 11d.

  As a result, the evaporation of the working medium 15 in the evaporation section 11d becomes insufficient, and the peak value P1p of the main container internal pressure P1 decreases, so that the performance of the liquid piston steam engine 10 decreases. In the worst case, the liquid phase portion of the working medium 15 does not reach the evaporation section 11d at the end of the second stroke, and the working medium 15 is not evaporated in the first stroke. Excited vibration stops.

  From the above, in order to maintain the self-excited vibration of the working medium 15 satisfactorily, the flow coefficient Cv of the communication portion 22 is set to a predetermined value or less, and the liquid phase portion of the working medium 15 is not changed at the end of the second stroke. It is necessary to always reach the evaporation part 11d.

  Specifically, if the flow coefficient Cv of the communication part 22 is set so as to satisfy the following mathematical formula 3, the liquid phase part of the working medium 15 can surely reach the evaporation part 11d at the end of the second stroke. .

Vh: Volume of the evaporation part 11d P1: Main container internal pressure P2: Auxiliary container internal pressure t1: Start time of the second stroke t2: End time of the second stroke In the above equation 3, the denominator in the right side is 2 corresponds to the difference (area S2−area S1) between the area of the hatching region S2 and the area of the hatching region S1 shown in FIG.

  That is, if the flow coefficient Cv of the communication part 22 satisfies the above mathematical formula 3, the amount of decrease in the liquid piston volume during the second stroke can be suppressed to be smaller than the volume Vh of the evaporation part 11d. It can be avoided that the liquid phase portion of the working medium 15 does not reach the portion 11d, and the self-excited vibration of the working medium 15 can be prevented from stopping.

  However, since the pressure waveform of the main container internal pressure P1 and the auxiliary container internal pressure P2 vary with the variation of the evaporation part temperature T1, the value of the denominator in the right side of Equation 3 also varies. The upper limit value of the flow coefficient Cv of the communication part 22 obtained by Expression 3 also varies.

  Therefore, in the present embodiment, the upper limit value of the flow coefficient Cv of the communication unit 22 is obtained based on the above Equation 3, and the control unit 21 opens the throttle of the variable throttle mechanism 25 according to the obtained upper limit value of the flow coefficient Cv. The degree is to be controlled. Thereby, even if the evaporation part temperature T1 fluctuates, the flow coefficient Cv of the communication part 22 can always satisfy the above mathematical formula 3.

  Even if the flow coefficient Cv of the communicating portion 22 is adjusted in this way, the volume of the liquid piston is somewhat reduced when the second stroke is performed once, but the self-excited vibration of the working medium 15 is maintained. Then, the liquid piston volume is increased thereafter, and the liquid piston volume returns to a predetermined amount.

  That is, when the volume of the liquid piston is somewhat reduced in the second stroke, the working medium 15 that evaporates in the evaporating portion 11d is reduced, and the average value P1a of the main container internal pressure P1 is reduced. Therefore, the auxiliary container internal pressure P2 also decreases following the average value P1a of the main container internal pressure P1, and the auxiliary container internal pressure P2 becomes lower than the target value P1A.

  Then, as described above, since the electric actuator 26b pushes out the pressure adjusting piston 26a to increase the auxiliary container internal pressure P2, the volume of the liquid phase portion of the working medium 15 flowing from the main container 11 into the auxiliary container 21 is larger. The volume of the liquid 23 flowing into the main container 11 from the auxiliary container 21 becomes larger. As a result, since the liquid piston volume increases, the liquid piston volume returns to a predetermined amount.

  By the way, as can be seen from FIG. 2, the pressure waveform of the main container pressure P1 approximates a sine curve (Sin curve). Therefore, in this example, in Equation 3 above, P1 (t) is approximated by a sine curve (Sin curve) to obtain the upper limit value of the flow coefficient Cv.

  More specifically, it is approximated by a sine curve in which the peak value P1p of the main container internal pressure P1 is the maximum value and the atmospheric pressure (0.1 MPa) is the minimum value. For this reason, since it is not necessary to sample the main container internal pressure P1 with a pressure sensor, cost can be reduced.

(Second Embodiment)
In the first embodiment, the flow coefficient Cv of the communication portion 22 is adjusted by the electric variable throttle mechanism 25 and the control device 27. In the second embodiment, as shown in FIG. The flow coefficient Cv of the communication part 22 is adjusted by forming the pipe wall 30 of the communication part 22 with a shape memory alloy.

  Although not shown, the tube wall 30 of the communication part 22 is thermally connected to the evaporation part 11d. More specifically, a material having excellent thermal conductivity (for example, copper) is disposed between the tube wall 30 and the evaporation portion 11d, and the temperature of the tube wall 30 changes according to the fluctuation of the evaporation portion temperature T1. It is supposed to be.

  When the evaporation portion temperature T1 is low and the temperature of the tube wall 30 is low, as shown in FIG. 7A, the tube wall 30 is deformed so that the flow path diameter of the communication portion 22 is increased, and the flow coefficient Cv is increased. It is getting bigger. On the other hand, when the evaporation portion temperature T1 is increased and the temperature of the tube wall 30 is increased, as shown in FIG. 7B, the tube wall 30 is deformed so that the flow path diameter of the communication portion 22 is reduced, and the flow coefficient Cv. Becomes smaller.

  That is, when the evaporation part temperature T1 increases, the main container internal pressure P1 increases, and the working medium 15 easily flows from the main container 11 into the auxiliary container 21, but in this embodiment, Since the flow coefficient Cv of the communication part 22 becomes small, the inflow of the working medium 15 from the main container 11 to the auxiliary container 21 can be suppressed.

  For this reason, it can be avoided that the liquid phase portion of the working medium 15 hardly reaches the evaporation portion 11d at the end of the second stroke and the performance of the liquid piston steam engine 10 is deteriorated.

  Furthermore, in this embodiment, the material, shape, and the like of the tube wall 30 (shape memory alloy) are selected so that the flow coefficient Cv substantially satisfies the above mathematical formula 3. For this reason, since the amount of decrease in the volume of the liquid piston in the second stroke can be suppressed to be smaller than the volume Vh of the evaporation unit 11d, it is possible to avoid the liquid phase portion of the working medium 15 from reaching the evaporation unit 11d. As a result, it can avoid that the self-excited vibration of the working medium 15 stops.

  In this example, the entire tube wall 30 of the communication portion 22 is formed of a shape memory alloy, but a part of the communication portion 22 is formed of a shape memory alloy, and only a portion of the tube wall 30 is shape memory. You may make it form with an alloy.

(Third embodiment)
In the second embodiment, the flow coefficient Cv of the communicating portion 22 is adjusted by forming the pipe wall 30 from a shape memory alloy. However, in the third embodiment, as shown in FIG. The flow coefficient Cv of the communicating portion 22 is adjusted by a mechanism 31 that displaces a part of the communication portion 22.

  A mechanism 31 for displacing a part of the tube wall 30 includes a fluid sealing portion 32 disposed on the outer periphery of the communication portion 22, a flow coefficient adjusting fluid 33 sealed in the fluid sealing portion 32, and the tube wall 30. An adjustment plate 34 that constitutes a part and partitions the space in the communication portion 22 and the space in the fluid sealing portion 32 is formed.

  The adjustment plate 34 enlarges or reduces the flow path diameter of the communication part 22 by the pressure balance between the flow coefficient adjusting fluid 33 in the fluid sealing part 32 and the working medium 15 or the liquid 23 in the communication part 22. Displaceable. For example, air or helium can be used as the flow coefficient adjusting fluid 33.

  Although not shown, the fluid sealing portion 32 is thermally connected to the evaporation portion 11d. More specifically, a material having excellent thermal conductivity (for example, copper) is disposed between the fluid sealing part 32 and the evaporation part 11d, and the inside of the fluid sealing part 32 is changed according to the fluctuation of the evaporation part temperature T1. The temperature of the flow coefficient adjusting fluid 33 is also changed.

  As shown in FIG. 8A, when the evaporation portion temperature T1 is low and the temperature of the flow coefficient adjusting fluid 33 is low, the flow coefficient adjusting fluid 33 is thermally contracted and the adjusting plate 34 is connected to the communication portion 22. It is displaced so as to increase the flow path diameter. For this reason, the flow coefficient Cv of the communication part 22 becomes large.

  On the other hand, as shown in FIG. 8B, when the evaporation portion temperature T1 is increased and the temperature of the flow coefficient adjusting fluid 33 is increased, the flow coefficient adjusting fluid 33 is thermally expanded, and the adjusting plate 34 is connected to the communicating portion 22. It is displaced so as to reduce the flow path diameter. For this reason, the flow coefficient Cv of the communication part 22 becomes small.

  Therefore, as in the second embodiment, the liquid phase portion of the working medium 15 is unlikely to reach the evaporation section 11d at the end of the second stroke, and the performance of the liquid piston steam engine 10 is deteriorated. Can be avoided.

  Furthermore, in this example, the components of the flow coefficient adjusting fluid 33, the enclosed volume, the shape of the adjusting plate 34, and the like are selected so that the flow coefficient Cv substantially satisfies the above mathematical formula 3. For this reason, the stop of the self-excited vibration of the working medium 15 can be avoided as in the second embodiment.

(Fourth embodiment)
In the first embodiment, the variable throttle mechanism 25 is disposed in the communication portion 22 so that the flow coefficient Cv of the communication portion 22 can be adjusted. However, in this embodiment, as shown in FIG. Instead of this, a fixed throttle 34 is arranged to make the flow coefficient Cv of the communication part 22 constant.

  FIG. 10 is a graph showing the relationship between the change in piston volume in the first and second strokes and the pressure waveforms of the main container internal pressure P1 and the auxiliary container internal pressure P2 as in FIG. A solid line P1max indicates the pressure waveform of the main container internal pressure P1 when the evaporation part temperature T1 is the maximum temperature, and a two-dot chain line P1min indicates the main container when the evaporation part temperature T1 is the minimum temperature. The pressure waveform of the internal pressure P1 is shown.

  Here, the “maximum temperature of the evaporation part temperature T1” means the maximum temperature of the evaporation part temperature T1 assumed under normal use conditions, and the “minimum temperature of the evaporation part temperature T1” means a normal temperature. It means the lowest temperature of the evaporation part temperature T1 assumed in the use conditions.

  Although not shown, when the evaporation portion temperature T1 is an intermediate temperature between the maximum temperature and the minimum temperature, the pressure waveform of the main container internal pressure P1 is an intermediate between the solid line P1max and the two-dot chain line P1min. become. Further, in FIG. 10, an alternate long and short dash line P2max indicates the auxiliary container internal pressure P2 when the evaporation portion temperature T1 is the lowest temperature.

  As can be seen from FIG. 10, if the flow coefficient Cv of the communication part 22 is constant, the volume of the liquid phase portion of the working medium 15 flowing from the main container 11 into the auxiliary container 21 is the maximum temperature of the evaporation part temperature T1. It becomes the largest when it is. For this reason, the amount of decrease in the volume of the liquid piston during the second stroke is maximized when the evaporator temperature T1 is at the maximum temperature.

  Therefore, in the present embodiment, the communication portion 22 is formed so that the flow coefficient Cv of the communication portion 22 satisfies the following mathematical formula 4. More specifically, the channel diameter, the channel length, the opening degree of the fixed throttle 34, and the like of the communication unit 22 are set so that the flow coefficient Cv of the communication unit 22 satisfies the following mathematical formula 4.

Vh: Volume of the evaporating part 11d P1max: Pressure inside the main container when the evaporating part temperature T1 is the highest temperature P2max: Pressure inside the auxiliary container when the evaporating part temperature T1 is the highest temperature t1: Second stroke Start time t2: end time of the second stroke In other words, if the flow coefficient Cv of the communicating portion 22 satisfies the above equation 4, even if the evaporation portion temperature T1 is at the maximum temperature, the second stroke is performed. The amount of decrease in the volume of the liquid piston during one operation can be suppressed to be smaller than the volume Vh of the evaporation unit 11d.

  For this reason, even if the evaporation part temperature T1 fluctuates, it can be avoided that the liquid phase part of the working medium 15 does not always reach the evaporation part 11d, and the self-excited vibration of the working medium 15 stops. Can be avoided.

  Note that the opening degree of the fixed throttle 34 may be set so that the flow coefficient Cv of the communicating portion 22 approximately satisfies the above mathematical formula 4. For example, since the auxiliary container internal pressure P2max is substantially equal to the average value of the main container internal pressure P1max, P2max (t) may be approximated by the average value of the main container internal pressure P1max in Equation 4 above.

(Other embodiments)
In each of the above embodiments, an example in which the present invention is applied to a so-called single-cylinder liquid piston steam engine 10 in which the entire main container 11 is formed in a single tubular shape is shown. The present invention is applied to a so-called multi-cylinder type liquid piston steam engine in which the portion on the evaporation section 11d side is constituted by a plurality of branch pipes and the remaining part of the main container 11 is constituted by a single collecting pipe. Is possible.

  In each of the above embodiments, an example in which the present invention is applied to a liquid piston steam engine 10 having only one main container 11 is shown. However, a plurality of main containers 11 are provided, and a plurality of main containers 11 are arranged as one. The present invention can be applied to a liquid piston steam engine connected by two output portions.

Further, in each of the above embodiments, the pressure adjusting means 26 for adjusting the auxiliary container internal pressure P2 is constituted by the pressure adjusting piston 26a and the electric actuator 26b. Similarly to the above, pressure adjusting means having various configurations can be used. For example,
Moreover, although each said embodiment demonstrated the case where this invention was applied to the drive source of an electric power generating apparatus, the external combustion engine of this invention can be utilized also as drive sources other than an electric power generating apparatus.

It is a block diagram showing schematic structure of the liquid piston steam engine by 1st Embodiment of this invention. It is a graph which shows the relationship between the change of the piston volume in a 1st, 2nd stroke, and the pressure waveform of the main container internal pressure and the auxiliary container internal pressure. It is a PV diagram explaining the relationship between the peak value of the pressure in the main container and the performance of the liquid piston steam engine. It is a block diagram which shows the outline | summary of control of the main container internal pressure in 1st Embodiment. It is sectional drawing explaining the flow coefficient of the connection piping in 1st Embodiment. It is a graph which shows the relationship between the flow coefficient of connection piping, and the efficiency of a liquid piston steam engine. It is a principal part expanded sectional view of the liquid piston steam engine by 2nd Embodiment of this invention, (a) has shown the case where evaporation part temperature is low, (b) has shown the case where evaporation part temperature is high. It is a principal part expanded sectional view of the liquid piston steam engine by 3rd Embodiment of this invention, (a) shows the case where evaporation part temperature is low, (b) has shown the case where evaporation part temperature is high. It is a block diagram showing schematic structure of the liquid piston steam engine by 4th Embodiment of this invention. It is a graph which shows the relationship between the evaporation part temperature and the pressure waveform of the pressure in a main container.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Main container, 11d ... Evaporating part, 11e ... Condensing part, 12 ... Output part, 15 ... Working medium,
21 ... Auxiliary container, 22 ... Communication part, 23 ... Liquid, 25 ... Variable throttle mechanism,
26 ... Pressure adjusting means, 27 ... Control device (control means).

Claims (4)

A tubular main container (11) in which a working medium (15) is enclosed in a liquid state so as to be flowable;
An evaporation section (11d) that is formed at a portion on one end side of the main container (11) and heats and evaporates a part of the working medium (15) in the main container (11);
The steam of the working medium (15) formed in a portion of the main container (11) on the other end side of the evaporation section (11d) and evaporated in the evaporation section (11d) is cooled and condensed. A condensing part (11e);
An output unit (12) that communicates with the other end of the main container (11), converts the displacement of the liquid phase portion of the working medium (15) into mechanical energy, and outputs the mechanical energy;
Auxiliary container (21) in which liquid (23) is sealed by communicating with a portion between said condensing part (11e) and said output part (12) in said main container (11) via communication part (22). )When,
Pressure adjusting means (26) for adjusting the internal pressure (P2) of the auxiliary container (21),
First, the evaporation medium (11d) evaporates the working medium (15) to displace the liquid phase portion of the working medium (15) from the evaporation section (11d) side toward the output section (12) side. The working medium (15) evaporated in the process and the first process is condensed in the condensing part (11e), and the liquid phase portion of the working medium (15) is transferred from the output part (12) side to the evaporation part. (11d) In the external combustion engine that alternately repeats the second stroke to be displaced toward the side,
The volume of the liquid phase portion of the working medium (15) flowing into the auxiliary container (21) from the main container (11) and the main container from the auxiliary container (21) during the second stroke. (11) The flow coefficient (Cv) of the communication part (22) is set so that the difference from the volume of the liquid (23) flowing into the liquid (23) is smaller than the volume (Vh) of the evaporation part (11d). An external combustion engine characterized by being. An electric variable throttle mechanism (25) disposed in the communication portion (22);
Control means (27) for controlling the throttle opening of the variable throttle mechanism (25) so that the flow coefficient (Cv) satisfies the following mathematical formula 1,
The external combustion engine according to claim 1, wherein the flow coefficient (Cv) is set by the variable throttle mechanism (25) and the control means (27).

Vh: Volume of the evaporation section (11d) P1: Internal pressure of the main container (11) P2: Internal pressure of the auxiliary container (21) t1: Start time of the second stroke t2: End time of the second stroke It comprises a changing means (30, 31) that is thermally connected to the evaporation section (11d) and is deformed by heat transferred from the evaporation section (11d) to change the flow path diameter of the communication section (22).
When the temperature (T1) of the evaporation section (11d) increases, the changing means (30, 31) decreases the flow path diameter of the communication section (22), and the temperature (T1) of the evaporation section (11d) decreases. Then, it is comprised so that the flow path diameter of the said communication part (22) may be enlarged,
The external combustion engine according to claim 1, wherein the flow coefficient (Cv) is set by the changing means (30, 31). The external combustion engine according to claim 1, wherein the communication part (22) is formed so that the flow coefficient (Cv) satisfies the following formula (2).

Vh: Volume of the evaporation section (11d) P1max: Internal pressure of the main container (11) when the temperature (T1) of the evaporation section (11d) is the maximum temperature P2max: Temperature (T1) of the evaporation section (11d) is the maximum temperature Internal pressure of auxiliary container (21) at time t1: Start time of second stroke t2: End time of second stroke

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