JP2019027318A - Waste heat recovery device - Google Patents

Abstract

To provide a waste heat recovery device for, when an output shaft of a steam turbine is cut off from an output shaft of an internal combustion engine by a clutch, suppressing the overspeed of the steam turbine while suppressing a reduction in the pressure of steam to be supplied to the steam turbine.SOLUTION: A control device of the waste heat recovery device adjusts an injection angle using a variable device so that the rotation speed of the steam turbine does not exceed an upper limit rotation speed when the output shaft of the steam turbine is cut off from the output shaft of the internal combustion engine by the clutch.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a waste heat recovery apparatus that recovers waste heat of an internal combustion engine, and more particularly, to a waste heat recovery apparatus suitable for waste heat recovery of an in-vehicle internal combustion engine.

  Patent Document 1 discloses a waste heat recovery device (Rankine cycle system) that includes a steam generator (boiler), a superheater, a steam turbine, and a condenser and recovers waste heat of an internal combustion engine. The waste heat recovery apparatus further includes a clutch that connects or disconnects the output shaft of the steam turbine and the output shaft of the internal combustion engine, a bypass passage that bypasses the steam turbine, and a bypass valve that opens and closes the bypass passage. .

  In the above waste heat recovery apparatus, when the engine speed exceeds a predetermined threshold, the output shaft of the steam turbine is disconnected from the output shaft of the internal combustion engine by the clutch. In addition, in order to suppress over-rotation of the steam turbine after the output shaft of the steam turbine is disconnected from the output shaft of the internal combustion engine, the steam is released to the bypass passage by opening the bypass valve.

Japanese Patent Laid-Open No. 2006-156342 Japanese Unexamined Patent Publication No. 01-262305 JP 2010-101283 A

  As described in Patent Document 1, when steam is released to the bypass passage in order to suppress over-rotation of the steam turbine, the pressure of the steam supplied to the steam turbine (more specifically, a nozzle that injects steam into the steam turbine) The pressure of the steam supplied to the As a result, when the output shaft of the steam turbine and the output shaft of the internal combustion engine are connected again by the clutch thereafter, there is a concern that the efficiency of the steam turbine is reduced.

  The present invention has been made in view of the above-described problems. When the output shaft of the steam turbine is disconnected from the output shaft of the internal combustion engine by the clutch, the pressure of the steam supplied to the steam turbine is reduced. It is an object of the present invention to provide a waste heat recovery device that can suppress over-rotation of a steam turbine while suppressing it.

The waste heat recovery apparatus according to the present invention is
A steam generator for generating steam by boiling a liquid-phase working fluid by waste heat of an internal combustion engine;
A steam turbine driven by steam generated in the steam generator;
A clutch that connects or disconnects the output shaft of the steam turbine and the output shaft of the internal combustion engine;
A variable device for varying an incident angle of a steam flow to a turbine blade of the steam turbine;
A control device for controlling the clutch and the variable device;
Is provided.
The control device uses the variable device so that the rotation speed of the steam turbine does not exceed an upper limit rotation speed when the output shaft of the steam turbine is disconnected from the output shaft of the internal combustion engine by the clutch. To adjust the incident angle.

  According to the present invention, when the output shaft of the steam turbine is disconnected from the output shaft of the internal combustion engine by the clutch, the incident angle is adjusted using the variable device so that the rotation speed of the steam turbine does not exceed the upper limit rotation speed. The By utilizing the adjustment of the incident angle, the steam supplied to the steam turbine is not bypassed. For this reason, it is possible to suppress the excessive rotation of the steam turbine while suppressing a decrease in the pressure of the steam supplied to the steam turbine.

It is a figure which shows typically the whole structure of the waste-heat recovery apparatus which concerns on embodiment of this invention. It is a figure for demonstrating the incident angle (alpha) of the steam flow with respect to a turbine blade. It is a figure which shows typically the structural example of two types of variable incident angle nozzles of a rotational type (A) and a slide type (B). It is a figure for demonstrating the influence of the incident angle (alpha) on the efficiency of a turbine. It is a time chart showing an example of operation of turbine revolving speed control concerning an embodiment of the present invention. It is a flowchart which shows the main routine of the process regarding the turbine rotation speed control which concerns on embodiment of this invention. It is a flowchart which shows the subroutine of the process of step S102 regarding clutch ON. It is a flowchart which shows the subroutine of the process of step S108 regarding adjustment of incident angle (alpha). It is a figure for demonstrating an example of the setting of the map used for calculation of incident angle (alpha). It is a time chart showing how the incident angle α is adjusted according to the rotational speed difference ΔNt. It is a flowchart which shows the subroutine of the process of step S112 regarding reconnection of a clutch.

  Embodiments of the present invention will be described below with reference to the drawings. However, the same reference numerals are given to common elements in the drawings, and redundant description is omitted. In addition, in the embodiment shown below, when referring to the number of each element, quantity, quantity, range, etc., unless otherwise specified or clearly specified in principle, the reference However, the present invention is not limited to these numbers. Further, the structures, steps, and the like described in the embodiments below are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

1. Configuration of Waste Heat Recovery Device The waste heat recovery device of the present embodiment is mounted on a vehicle and recovers waste heat of an internal combustion engine that is a power device of the vehicle.

1-1. Overall Configuration of Waste Heat Recovery Apparatus FIG. 1 is a diagram schematically showing an overall configuration of a waste heat recovery apparatus 10 according to an embodiment of the present invention. The waste heat recovery apparatus 10 shown in FIG. 1 is configured as a Rankine cycle system. In this embodiment, water is used as an example of the working fluid of this Rankine cycle system. The waste heat recovery apparatus 10 includes a heat source side device 12, a nozzle 14, a steam turbine (hereinafter also simply referred to as “turbine”) 16, a cooling side device 18, and a pump 20 on a passage 11 through which a working fluid flows. It has.

  The heat source side device 12 includes a superheater as an example together with a steam generator. The steam generator is configured to generate steam by boiling the liquid-phase working fluid flowing through the passage 11 by waste heat of the internal combustion engine (engine) 1. The superheater superheats the vapor phase working fluid, which is saturated steam generated in the steam generator, by heat exchange with exhaust gas, for example, to form superheated steam. The heat source of the steam generator is not particularly limited. For example, waste heat such as engine cooling water or intake air supercharged in a supercharger can be used as the heat source. Moreover, it is not restricted to a single heat source, It may generate steam by a plurality of heat sources.

  The turbine 16 expands the vapor-phase working fluid sent from the heat source side device 12 and recovers thermal energy. The nozzle 14 is provided upstream of the turbine 16. The gas phase working fluid is sprayed from the nozzle 14 to the turbine blade 16 a of the turbine 16 to rotate the turbine 16.

  The cooling side device 18 includes a condenser (condenser) and a catch tank. The gas phase working fluid expanded by the turbine 16 is sent to this condenser. The vapor-phase working fluid sent to the condenser is cooled and condensed by the condenser and returned to the liquid-phase working fluid. The liquid-phase working fluid generated by the condensation of the gas-phase working fluid is sent from the condenser to the catch tank and is temporarily stored in the catch tank.

  The pump 20 is disposed on the passage 11 between the cooling side device 18 and the heat source side device 12. The pump 20 is a pump for sending the liquid-phase working fluid stored in the catch tank of the cooling side device 18 to the steam generator of the heat source side device 12.

  An output shaft (rotary shaft) 16 b of the turbine 16 is mechanically connected to the output shaft 1 a of the engine 1 via the speed reduction mechanism 22. More specifically, the speed reduction ratio R of the speed reduction mechanism 22 is a value greater than 1, and is determined so that the turbine speed Nt is higher than the engine speed Ne (Nt = R × Ne). The thermal energy recovered by the turbine 16 is recovered by the engine 1 as power for assisting the rotation of the engine 1.

  The waste heat recovery apparatus 10 further includes a clutch 24 for connecting or disconnecting the output shaft 16 b of the turbine 16 and the output shaft 1 a of the engine 1. The position of the clutch 24 is not particularly limited as long as it is on the power transmission path between the turbine 16 and the engine 1. A rotation speed sensor 26 for measuring the turbine rotation speed Nt is attached to the output shaft 16 b of the turbine 16. The rotational speed sensor 26 is provided at a position where the turbine rotational speed Nt can be detected even when the turbine 16 is disconnected from the engine 1 by the clutch 24.

1-2. Structural Example of Variable Incident Angle Nozzle FIG. 2 is a diagram for explaining the incident angle α of the steam flow with respect to the turbine blade 16a. Here, a plane perpendicular to the axial direction of the turbine 16 and passing through the center of the thickness of the turbine blade 16 a is referred to as a “reference plane S” of the turbine 16. In the configuration of the present embodiment, as shown in FIG. 2, the incident angle α corresponds to an angle formed by the reference plane S and the direction D of the steam flow sprayed from the nozzle 14 to the turbine blade 16 a. The incident angle α has a value of 0 when the steam from the nozzle 14 pushes the turbine blade 16a in the direction of rotation and the steam flow direction D is parallel to the reference plane S. Defined as ° (where 0 ° is not a feasible value).

  Parameters affecting the turbine performance include the pressure on the heat source side (that is, the pressure of steam supplied to the turbine 16 (more specifically, the nozzle 14)), the amount of steam, and the above-described incident angle α of steam. It is done. The efficiency of the turbine 16 increases as the incident angle α decreases.

  More specifically, the nozzle 14 of the present embodiment is configured to change the incident angle α. Therefore, hereinafter, the nozzle 14 is also referred to as “variable incident angle nozzle 14”. FIG. 3 is a diagram schematically showing an example of the structure of two types of variable incident angle nozzles, a rotary type (A) and a slide type (B). The rotary type shown in FIG. 3A is an example employed in this embodiment. In this example, the variable incident angle nozzle 14 is configured to be rotatable in such a manner that the direction D of the steam flow with respect to the reference surface S is changed by a drive mechanism (not shown). According to such a structural example, the incident angle α can be changed by changing the direction D. In addition, as shown in FIG. 1, an angle sensor 28 that detects the rotation angle of the nozzle 14 is provided to grasp the incident angle α.

  On the other hand, in the sliding type example shown in FIG. 3B, the nozzle is configured to be slidable in a manner in which the nozzle rotates around the intersection P between the reference plane S and the direction D by a driving mechanism (not shown). Yes. In this example, the connection passage located between the nozzle and the passage on the upstream side thereof may be constituted by, for example, a flexible pipe (or hose) in order to absorb the change in the position of the nozzle with respect to the passage. . Even with such a structural example, the incident angle α can be changed by changing the direction D. Note that any structure other than the structural example illustrated here may be adopted as long as only the incident angle α can be changed without changing the opening area of the nozzle.

1-3. Control Device The waste heat recovery device 10 further includes an electronic control unit (ECU) 30 as a control device that controls the clutch 24 and the variable incident angle nozzle 14. The ECU 30 includes at least an input / output interface, a memory, and a processor. The input / output interface captures sensor signals from various sensors and outputs operation signals to the clutch 24 and the variable incident angle nozzle 14. The various sensors referred to here include a crank angle sensor 32 for obtaining the engine rotational speed Ne together with the rotational speed sensor 26 and the angle sensor 28 described above. The memory stores various control programs and maps. The processor reads the control program from the memory and executes it, and generates an operation signal for the clutch 24 and the variable incident angle nozzle 14 based on the acquired sensor signal.

2. 2. Turbine rotational speed control at clutch disconnection 2-1. Turbine over-speed due to clutch disengagement for turbine protection etc. If the engine speed Ne rises while the clutch 24 is engaged, the turbine speed Nt may become too high depending on how the engine speed Ne rises. is there. More specifically, the reason why the turbine 16 over-rotates as the engine speed Ne increases is that, for example, it is desired to secure a high turbine speed Nt that provides high efficiency in the normal range of the engine speed Ne. This is because the reduction ratio R is increased.

  In the present embodiment, when the turbine rotation speed Nt reaches a predetermined upper limit rotation speed Ntmax, the clutch 24 is disconnected for reasons such as protection of the turbine 16. However, when the clutch 24 is disengaged, the turbine 16 is in an unloaded state, and thus the turbine 16 may be over-rotated.

2-2. Influence of Incident Angle α on Turbine Efficiency FIGS. 4A to 4C are diagrams for explaining the influence of the incident angle α on the efficiency of the turbine 16.

  FIG. 4A shows the positional relationship between the variable incident angle nozzle 14 and the turbine blade 16a when the incident angle α is the minimum value αmin (0 ° <αmin <90 °). As described above, the efficiency of the turbine 16 increases as the incident angle α decreases. This is because when the incident angle α is small, the steam from the variable incident angle nozzle 14 can efficiently push the turbine blade 16a in the rotation direction. For this reason, the minimum value αmin is used as the incident angle α at the time of waste heat recovery (that is, when the clutch 24 is engaged). The value of the minimum value αmin is set according to the system to be constructed as the minimum incident angle α that can be taken in consideration of the nozzle diameter and the component strength.

  FIG. 4B shows the positional relationship between the variable incident angle nozzle 14 and the turbine blade 16a when the incident angle α is 90 °. In this case, the steam from the variable incident angle nozzle 14 strikes the turbine blade 16a horizontally. For this reason, the rotational force (driving force) of the turbine 16 is not substantially generated by the spraying of steam in this case.

  FIG. 4C shows the positional relationship between the variable incident angle nozzle 14 and the turbine blade 16a when the incident angle α is greater than 90 °. When the incident angle α exceeds 90 ° as in this example, the steam from the variable incident angle nozzle 14 is in a direction opposite to the normal rotation direction of the turbine blade 16a as shown in FIG. 4C. It is sprayed to 16a. For this reason, the spraying of steam in this case acts as a braking force that reduces the rotation of the turbine blade 16a. Note that the maximum value αmax of the incident angle α is a system that is constructed as the maximum incident angle α (less than 180 °) that can be taken in consideration of the nozzle diameter and the component strength, as in the setting of the minimum value αmin. Is set according to

2-3. Overview of Turbine Speed Control at Clutch Disengagement As can be seen from the description with reference to FIGS. 4 (A) to 4 (C), the turbine blade 16a can be changed from steam by increasing or decreasing the incident angle α on the basis of 90 °. A driving force or a braking force can be applied. Therefore, in the present embodiment, when the output shaft 16b of the turbine 16 is disconnected from the output shaft 1a of the engine 1 by the clutch 24, the adjustment of the incident angle α is used for controlling the turbine rotational speed Nt. Specifically, in order to prevent the turbine speed Nt from exceeding the upper limit speed Ntmax, the incident angle α is adjusted using the variable incident angle nozzle 14 so that the turbine speed Nt approaches the upper limit speed Ntmax. Is done.

  FIG. 5 is a time chart showing an example of the operation of the turbine rotation speed control according to the embodiment of the present invention. 5, the solid line indicates the product (Ne × R) of the engine speed Ne and the reduction ratio R, that is, the output shaft 16b of the turbine 16 and the rotating shaft 34 on the engine 1 side to be connected (see FIG. 5). 1), and the broken line is the turbine speed Nt. Both are equal during clutch 24 engagement.

  In a period before time t1 in FIG. 5, the clutch 24 is turned on (connected state), and waste heat recovery is performed. During this period, the variable incident angle nozzle 14 is controlled so that the incident angle α becomes the minimum value αmin. During this period, the turbine rotational speed Nt (in this case, equal to the rotational speed (Ne × R) of the rotating shaft 34) increases as the engine rotational speed Ne increases.

  The time point t1 corresponds to a time point when the turbine rotational speed Nt reaches the upper limit rotational speed Ntmax while the clutch 24 is engaged. According to the turbine rotational speed control of the present embodiment, at the time point t1, the clutch 24 is turned off (disconnected), and the adjustment of the incident angle α is started. At the time point t1, the incident angle α is controlled to be larger than 90 ° in order to suppress over-rotation of the turbine 16 exceeding the upper limit rotational speed Ntmax.

  A time point t2 after the time point t1 corresponds to a time point when the rotational speed (Ne × R) of the rotary shaft 34 has decreased to the upper limit rotational speed Ntmax as the engine rotational speed Ne decreases. During the period from time t1 to time t2 (t1-t2), the turbine rotational speed Nt deviates from the rotational speed (Ne × R) of the rotating shaft 34 as the clutch 24 is disengaged.

  In the period (t1-t2), the turbine rotational speed control will be described in detail later with reference to FIGS. 8 to 10. However, the rotational speed difference between the measured value of the turbine rotational speed Nt by the rotational speed sensor 26 and the upper limit rotational speed Ntmax. The incident angle α is adjusted so that ΔNt (the absolute value thereof) becomes small. Thereby, the turbine speed Nt is brought close to the upper limit speed Ntmax. As described above, the turbine rotational speed control of the present embodiment using the adjustment of the incident angle α is different from the conventional method in which the steam generated in the heat source side device 12 is released to the bypass passage, and the turbine rotational speed Nt is adjusted. Therefore, it does not control the steam pressure. For this reason, also during a period (t1-t2), as shown in FIG. 5, the heat-source side pressure (pressure of the steam supplied to the turbine 16 (nozzle 14)) can be maintained high.

  At the time point t2, the clutch 24 is turned on again (reconnected). More specifically, as shown in FIG. 11 described later, the reconnection of the clutch 24 is executed when the rotational speed (Ne × R) of the rotating shaft 34 becomes equal to the turbine rotational speed Nt.

  When the clutch 24 is reconnected, waste heat recovery is resumed. As described above, according to the turbine rotation speed control of the present embodiment, the heat source side pressure is kept high even during the period (t1-t2), so that it is high when the waste heat recovery is resumed after time t2. It becomes possible to obtain a high turbine output under the turbine rotational speed Nt. In addition, since the incident angle α is controlled to the minimum value αmin at time t2, waste heat recovery can be resumed while increasing the efficiency of the turbine 16 to the maximum in terms of the incident angle α.

2-4. FIG. 6 is a flowchart showing a main routine of processing related to turbine rotational speed control according to the embodiment of the present invention. In the main routine shown in FIG. 6, the ECU 30 determines whether or not the engine is ON, that is, whether or not the engine 1 is started (step S100).

  If it is determined in step S100 that the engine is not turned on, the ECU 30 ends the current processing cycle of this routine. On the other hand, when it is determined in step S100 that the engine is turned on, the ECU 30 executes a process for turning on (connecting) the clutch 24 (step S102).

  FIG. 7 is a flowchart showing a subroutine of the process of step S102 regarding the clutch ON. In the subroutine shown in FIG. 7, the ECU 30 confirms that the turbine rotational speed Nt is not 0 (step S200). Next, the ECU 30 acquires the rotational speed (Ne × R) of the rotating shaft 34 and the turbine rotational speed Nt (step S202). The rotational speed (Ne × R) of the rotary shaft 34 is calculated by multiplying the engine speed Ne obtained by the crank speed sensor 32 and then multiplying the acquired engine rotational speed Ne by a predetermined reduction ratio R. The The turbine rotational speed Nt is detected using the rotational speed sensor 26.

  Next, the ECU 30 determines whether or not the rotational speed (Ne × R) of the rotating shaft 34 acquired in step S202 is equal to the turbine rotational speed Nt (step S204). As a result, when this determination is not satisfied, the process of step S202 is repeatedly executed. On the other hand, when it is determined that this determination is established, the ECU 30 turns on (couples) the clutch 24 (step S206). In addition, when the waste heat recovery device 10 is applied to a system (for example, an idling stop system or a hybrid system) in which the engine is repeatedly stopped and started while the vehicle is operating, the clutch is connected when the engine is stopped and the engine is restarted. It may become a state. For this reason, in such a system, it is desirable that a sufficient clutch capacity is ensured so as to be able to cope with a sudden change in the turbine speed Nt when the engine is stopped and the engine is restarted.

  In the main routine shown in FIG. 6, after the clutch 24 is turned on in step S102, the ECU 30 determines whether or not the rotational speed (Ne × R) of the rotating shaft 34 is equal to or higher than the (turbine) upper limit rotational speed Ntmax. (Step S104). The upper limit rotational speed Ntmax is a predetermined value. As a result, when this determination is not established, the ECU 30 ends the current processing cycle of this routine. On the other hand, when it is determined that the rotation speed (Ne × R) of the rotating shaft 34 is equal to or higher than the upper limit rotation speed Ntmax, the ECU 30 executes a process for turning off (disconnecting) the clutch 24 (step S106). .

  Next, the ECU 30 executes a process for adjusting the incident angle α (step S108). FIG. 8 is a flowchart showing a subroutine of the process of step S108 relating to the adjustment of the incident angle α. In the subroutine shown in FIG. 8, the ECU 30 calculates a rotational speed difference ΔNt (= Nt−Ntmax) between the turbine rotational speed Nt and the upper limit rotational speed Ntmax (step S300).

  Next, the ECU 30 calculates the incident angle α corresponding to the above rotation speed difference ΔNt (step S302). FIG. 9 is a diagram for explaining an example of setting of a map used for calculating the incident angle α. The map shown in FIG. 9 defines the relationship between the rotation speed difference ΔNt and the incident angle α as follows with the incident angle α of 90 ° as a reference (that is, zero).

  Specifically, in the map shown in FIG. 9, a predetermined maximum value ΔNtmax (positive value) of the rotational speed difference ΔNt is associated with a maximum value αmax of the incident angle α, and the predetermined minimum value of the rotational speed difference ΔNt is associated. While associating ΔNtmin (negative value) with the minimum value αmin of the incident angle α, the incident angle α corresponding to the rotation speed difference ΔNt is set as follows. That is, when the rotational speed difference ΔNt is a positive value, that is, when the turbine rotational speed Nt is higher than the upper limit rotational speed Ntmax, the incident angle α is made larger than 90 ° in order to decelerate the turbine 16. . Conversely, when the rotational speed difference ΔNt is a negative value, that is, when the turbine rotational speed Nt is lower than the upper limit rotational speed Ntmax, the incident angle α is smaller than 90 ° in order to increase the turbine 16 speed. Is done. For example, when the turbine speed Nt is higher than the upper limit speed Ntmax by 100 rpm, the incident angle α is increased to α1 larger than 90 °, and conversely, the turbine speed Nt is 100 rpm higher than the upper limit speed Ntmax. If it is only low, the angle of incidence α is reduced to α2, which is smaller than 90 °.

  More specifically, according to the map shown in FIG. 9, the incident angle α is increased as the positive rotational speed difference ΔNt increases, and conversely, the incident angle α is negative when the rotational speed difference ΔNt is negative. The larger the absolute value, the larger. According to the map setting described above, the incident angle α is adjusted so that the rotation speed difference ΔNt (absolute value thereof) becomes small.

  Next, the ECU 30 controls the variable incident angle nozzle 14 so that the incident angle α is changed to a value calculated with reference to the map (step S304). FIG. 10 is a time chart showing how the incident angle α is adjusted according to the rotation speed difference ΔNt. In the example illustrated in FIG. 10, in the period in which the rotation speed difference ΔNt is positive (period (t1′−t2 ′) and period after the time point t3 ′), the angular range is larger than 90 °. The incident angle α is adjusted according to a change in the positive rotation speed difference ΔNt. On the other hand, in the period (t2′−t3 ′) in which the rotational speed difference ΔNt is negative, the incident angle α is adjusted according to the change in the negative rotational speed difference ΔNt within an angle range smaller than 90 °. . In the period before t1 ', since the rotation speed difference ΔNt is zero, the incident angle α is held at 90 °.

  In the main routine shown in FIG. 6, after adjusting the incident angle α in step S108, the ECU 30 determines whether or not the rotational speed (Ne × R) of the rotating shaft 34 is less than the (turbine) upper limit rotational speed Ntmax. (Step S110). As a result, when this determination is not established, the ECU 30 ends the current processing cycle of this routine. On the other hand, when it is determined that the rotation speed (Ne × R) of the rotating shaft 34 is less than the upper limit rotation speed Ntmax, the ECU 30 executes a process for reconnecting the clutch 24 (step S112).

  FIG. 11 is a flowchart showing a subroutine of the process of step S112 regarding the reconnection of the clutch 24. In the subroutine shown in FIG. 11, the ECU 30 acquires the rotational speed (Ne × R) of the rotary shaft 34 and the turbine rotational speed Nt (step S400). Next, the ECU 30 determines whether or not the rotational speed (Ne × R) of the rotating shaft 34 acquired in step S400 is equal to the turbine rotational speed Nt (step S402).

  As a result, when the determination in step S402 is not established, the process in step S400 is repeatedly executed. On the other hand, when it is determined that this determination is established, the ECU 30 turns on (couples) the clutch 24 (step S404). Next, the ECU 30 executes a process of changing the incident angle α to the minimum value αmin (step S406).

  According to the processing of the routine shown in FIG. 6 described above, when the output shaft 16b of the turbine 16 is disconnected from the output shaft 1a of the engine 1 by the clutch 24, the incident angle α is reduced so that the rotational speed difference ΔNt is reduced. By adjusting this, the turbine rotational speed Nt can be brought close to the upper limit rotational speed Ntmax. Thereby, the incident angle α can be adjusted so that the turbine speed Nt does not exceed the upper limit speed Ntmax. And according to utilization of adjustment of incident angle alpha, as already stated, the steam supplied to turbine 16 is not bypassed. For this reason, according to the turbine rotation speed control of the present embodiment, it is possible to suppress over-rotation of the turbine 16 while suppressing a decrease in the pressure of the steam supplied to the turbine 16 (nozzle 14).

  Further, in the conventional method for controlling the turbine speed Nt by allowing steam to escape to the bypass passage, a response delay occurs in the adjustment of the turbine speed Nt by the steam pressure due to the presence of the volume of the heat source side equipment. It's not good. On the other hand, according to the turbine speed control of the present embodiment using the incident angle α, the turbine speed Nt is set to the upper limit speed Ntmax during the period in which the clutch 24 is disengaged without the influence of the response delay. You can keep it close. For this reason, when the turbine rotation speed Nt falls to the upper limit rotation speed Ntmax, the clutch 24 can be quickly reconnected (reconnected).

3. In the first embodiment described above, the variable incident angle nozzle capable of changing the incident angle α of the steam flow with respect to the turbine blade 16a by changing the position of the nozzle 14 is “variable. An example provided as "apparatus" is shown. However, the variable device according to the present invention only needs to be able to change the incident angle of the steam flow with respect to the turbine blade, and may have the following configuration, for example. In other words, the variable device may be capable of changing the angle of the turbine blade in place of or along with the position of the nozzle. Further, the variable device may be capable of changing the angle of the turbine (the output shaft thereof) instead of or along with the position of the nozzle.

DESCRIPTION OF SYMBOLS 1 Engine 1a Engine output shaft 10 Waste heat recovery apparatus 12 Heat source side apparatus 14 Nozzle (variable incident angle nozzle)
16 turbine 16a turbine blade 16b turbine output shaft 18 cooling side equipment 20 pump 22 speed reduction mechanism 24 clutch 30 electronic control unit (ECU)

Claims (1)

A steam generator for generating steam by boiling a liquid-phase working fluid by waste heat of an internal combustion engine;
A steam turbine driven by steam generated in the steam generator;
A clutch that connects or disconnects the output shaft of the steam turbine and the output shaft of the internal combustion engine;
A variable device for varying an incident angle of a steam flow to a turbine blade of the steam turbine;
A control device for controlling the clutch and the variable device;
A waste heat recovery device comprising:
The control device uses the variable device so that the rotation speed of the steam turbine does not exceed an upper limit rotation speed when the output shaft of the steam turbine is disconnected from the output shaft of the internal combustion engine by the clutch. And adjusting the incident angle.

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