JP5653320B2 - Waste heat regeneration system - Google Patents

Description

  The present invention relates to an exhaust heat regeneration system that regenerates exhaust heat from cooling water or exhaust gas for cooling an engine of an automobile or the like as power by using a Rankine cycle.

  Conventional waste heat utilization devices include a pump that pumps a liquid phase working fluid (liquid phase refrigerant), a heat generating device (evaporator) that heats the liquid refrigerant to form a gas phase working fluid (gas phase refrigerant), a gas phase A Rankine cycle comprising an expander that converts the energy of the working fluid (gas-phase refrigerant) into mechanical energy, a condenser that condenses and liquefies the expanded gas-phase refrigerant flowing out of the expander and sends it to a pump; The expander, the pump, and the electric motor are connected coaxially, the suction side and the discharge side of the expander are bypassed by the bypass flow path, and opening / closing means for opening and closing the bypass flow path is provided (for example, , See Patent Document 1).

  In the conventional waste heat utilization device, the opening / closing means is opened at the time of startup, and most of the liquid-phase refrigerant guided to the suction side of the expander is guided to the discharge side of the expander without passing through the expander. As a result, the start-up of the Rankine cycle was stabilized.

JP 2009-97387 A

  However, in the conventional waste heat utilization device, by opening and closing the opening / closing means, most of the gas-phase refrigerant is guided to the discharge side of the expander without passing through the expander, thereby stabilizing the start-up. However, the inflow amount of the gas-phase refrigerant sucked into the expander during operation cannot be adjusted.

  Here, since the pump and the expander are connected coaxially, the pump and the expander are rotated at the same rotational speed.

In an exhaust heat regeneration system of the same type as a conventional waste heat utilization device, the amount of refrigerant (liquid phase) discharged from the pump, the expander, except when the pump and the expander are rotated at a specific rotation speed The amount of refrigerant (gas phase) that can be properly processed is different.
In a system of the same type as a conventional waste heat utilization device, if the amount of refrigerant discharged from the pump is larger than the amount of refrigerant properly processed by the expander, the pressure on the discharge side of the pump becomes abnormally high, There is a risk of damage to the equipment through which the refrigerant flows.

  The present invention has been made to solve the above-described problems, and the pump and the expander are integrally driven under the condition that the amount of refrigerant discharged from the pump is larger than the amount of refrigerant properly processed by the expander. Even if it is, it aims at obtaining the exhaust heat regeneration system which can adjust the quantity of the refrigerant | coolant which flows in into an expander in the quantity which can be appropriately processed with an expander.

  An exhaust heat regeneration system according to the present invention includes an expander that expands the refrigerant to generate a driving force, a condenser that condenses the refrigerant from the expander, and an output shaft that transmits the driving force of the expander. A heat recovery system comprising a pump that pumps the refrigerant from the condenser and an evaporator that heats the refrigerant from the pump 4 and sends it to the expander, from the pump to the evaporator A flow rate adjusting means that configures a first bypass flow path that connects between the refrigerant flow path and the refrigerant flow path that extends from the expander to the pump via the condenser, and that can adjust the flow rate of the refrigerant flowing through the first bypass flow path. A first bypass means having a first pressure sensor for obtaining information on the pressure of the refrigerant pumped from the pump, and a refrigerant flow rate control means for controlling the driving of the flow rate adjusting means based on the output of the first pressure sensor. It has.

  According to the exhaust heat regeneration system according to the present invention, even when the pump and the expander are integrally driven under the condition that the amount of refrigerant pumped from the pump is larger than the amount of refrigerant properly processed by the expander, Based on the output of the first pressure sensor, among the refrigerant pumped from the pump, an appropriate amount of refrigerant is passed from the expander to the pump through the condenser to the low-pressure side refrigerant flow path via the first bypass flow path. By returning, the flow rate of the refrigerant flowing into the expander becomes a flow rate that can be appropriately processed by the expander, and thus damage to the device due to an abnormal pressure increase of the refrigerant can be prevented.

It is a block diagram of the waste heat regeneration system which concerns on Embodiment 1 of this invention. It is a figure which shows the flow volume characteristic of the refrigerant | coolant about each of the expander and pump which comprise the waste heat regeneration system which concerns on Embodiment 1 of this invention. It is a Mollier diagram of a Rankine cycle which is a thermodynamic cycle of a reference exhaust heat regeneration system, and shows a state where a pump and an expander are rotated at an adapted rotation speed. It is a Mollier diagram of Rankine cycle which is a thermodynamic cycle of the exhaust heat regeneration system of a reference example, and shows a mode in case a pump and an expander are rotated at a rotational speed slower than a suitable rotational speed. It is a Mollier diagram of a Rankine cycle which is a thermodynamic cycle of the exhaust heat regeneration system of a reference example, and shows a mode in a case where a pump and an expander are rotated at a rotational speed faster than a compatible rotational speed. It is a flowchart explaining operation | movement of the exhaust heat regeneration system which concerns on Embodiment 1 of this invention. It is a Mollier diagram of Rankine cycle which is a thermodynamic cycle of the exhaust heat regeneration system concerning Embodiment 1 of this invention, and shows a case where pump 4 and an expander are rotating faster than a suitable rotation speed. It is a block diagram of the waste heat regeneration system which concerns on Embodiment 2 of this invention. It is a block diagram of the waste heat regeneration system which concerns on Embodiment 3 of this invention. It is a flowchart explaining operation | movement of the exhaust heat regeneration system which concerns on Embodiment 3 of this invention. It is a Mollier diagram of Rankine cycle which is a thermodynamic cycle of the exhaust heat regeneration system concerning Embodiment 3 of this invention, and shows a case where an expander is rotated at a speed faster than an adapted rotation speed. It is a block diagram of the waste heat regeneration system which concerns on Embodiment 4 of this invention. It is a block diagram of the waste heat regeneration system which concerns on Embodiment 5 of this invention.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

Embodiment 1 FIG.
1 is a configuration diagram of an exhaust heat regeneration system according to Embodiment 1 of the present invention. FIG. 1 shows an exhaust heat regeneration system that uses exhaust heat from an engine that generates driving force of an automobile.

In FIG. 1, an exhaust heat regeneration system 1 </ b> A includes an expander 2 that expands a refrigerant to generate a driving force, a condenser 3 that condenses the refrigerant from the expander 2, and a pump that pumps the refrigerant from the condenser 3. 4 and an evaporator 5 that heats the refrigerant from the pump 4 by heat introduced from the outside and sends the refrigerant to the expander 2. Here, the heat introduced from the outside is the heat of the cooling water of the engine 8 heated by the engine 8.
Although R134a is used as the refrigerant, it is not limited to this.

  In addition, the exhaust heat regeneration system 1A includes a first bypass flow that connects a refrigerant flow path from the pump 4 to the evaporator 5 and a refrigerant flow path from the expander 2 to the pump 4 via the condenser 3. The information about the pressure of the refrigerant | coolant pumped from the 1st bypass means 10A which has the flow volume adjustment valve 11 as a flow volume adjustment means which comprises a path and can adjust the flow volume of the refrigerant | coolant which flows through a 1st bypass flow path, and the pump 4 is shown. A first pressure sensor 13 to be acquired, a first temperature sensor 14 as a high-pressure side temperature sensor to acquire information on the temperature of the refrigerant flowing into the expander 2, and a flow rate adjustment valve based on the output of the first pressure sensor 13 11 and a refrigerant flow rate control means 16 for controlling the rotational speed of the expander 2 based on the output of the first temperature sensor 14.

  The exhaust heat regeneration system 1A includes a first pipe 21 that guides the refrigerant from the evaporator 5 to the expander 2, a second pipe 22 that guides the refrigerant from the expander 2 to the condenser 3, and the refrigerant from the condenser 3 to the pump 4. A third pipe 23 for guiding and a fourth pipe 24 for guiding the refrigerant from the pump 4 to the evaporator 5 are provided.

Cooling water that circulates between the evaporator 5 flows through the engine 8.
Connected between the evaporator 5 and the engine 8 are a low temperature side pipe 9 a that guides cooling water from the evaporator 5 to the engine 8 and a high temperature side pipe 9 b that guides cooling water from the engine 8 to the evaporator 5. .
Then, the cooling water is led from the evaporator 5 to the engine 8 through the low temperature side pipe 9a, and is heated by taking the heat (waste heat) of the engine 8 and then heated through the high temperature side pipe 9b. It circulates in the circulation path | route which flows inside and flows through the low temperature side piping 9a again.

The first bypass means 10 </ b> A includes a flow rate adjustment valve 11 and a bypass pipe 12 </ b> A that forms a first bypass flow path from the fourth pipe 24 to the second pipe 22 via the flow rate adjustment valve 11. . That is, the first bypass flow path connects the refrigerant flow path from the pump 4 to the evaporator 5 and the refrigerant flow path from the expander 2 to the condenser 3.
More specifically, the bypass pipe 12 </ b> A includes a fifth pipe 12 a that forms a refrigerant flow path from the fourth pipe 24 to the flow control valve 11, and a refrigerant flow path from the flow control valve 11 to the second pipe 22. The 6th piping 12b which forms is provided.

  And the flow volume of the refrigerant | coolant which flows through a 1st bypass flow path can be adjusted by adjusting the opening degree of the flow regulating valve 11.

The expander 2 and the pump 4 are connected via an output shaft 7 so that the driving force of the expander 2 is transmitted to the pump 4. The expander 2 and the pump 4 are integrally attached to the housing 6.
An output shaft 7 that rotates around the shaft in conjunction with the drive of the expander 2 and the pump 4 extends from the housing 6. A generator 30 as a rotating electrical machine having a rotor (not shown) is connected to the output shaft 7 so that the rotor is rotated in conjunction with the rotation of the output shaft 7.

The first pressure sensor 13 is, for example, a resistance strain cage pressure sensor, and the first temperature sensor 14 is, for example, a thermistor or a thermocouple.
The 1st pressure sensor 13 is provided in the 4th piping 24 so that the information about the pressure of the refrigerant pumped from pump 4 can be acquired.
The 1st temperature sensor 14 is provided in the 1st piping 21 so that the information regarding the temperature of the refrigerant | coolant which flows in into the expander 2 can be acquired.

The refrigerant flow control means 16 is, for example, a microcomputer having a CPU, a RAM, a ROM, and the like (not shown), and can read the outputs of the first pressure sensor 13 and the first temperature sensor 14, 1 It is connected to the temperature sensor 14.
The refrigerant flow rate control means 16 is connected to the flow rate adjustment valve 11 so that the drive of the flow rate adjustment valve 11 can be controlled. The flow rate adjusting valve 11 is configured such that the opening degree of the valve is set based on a control command value output from the refrigerant flow rate control means 16.

  Moreover, the refrigerant | coolant flow control means 16 is connected to the expander 2 so that the rotational speed of the expander 2 is controllable. Specifically, the refrigerant flow control means 16 can set a torque (absorption torque) necessary for rotating a rotor of the generator 30 (not shown). That is, when the absorption torque is increased, the torque required to rotate the output shaft 7 is increased, so that the rotation speed of the expander 2 rotated by the circulation of the refrigerant is decreased. On the other hand, if the absorption torque is reduced, the torque required to rotate the output shaft 7 is reduced, so that the rotational speed of the expander 2 is increased.

Next, refrigerant flow rate characteristics of the expander 2 and the pump 4 constituting the exhaust heat regeneration system 1A will be described.
The refrigerant flow rate characteristic of the expander 2 is the maximum refrigerant flow rate that can be appropriately processed by the expander 2 with respect to the rotation speed of the expander 2, and the refrigerant flow rate characteristic of the pump 4 is the rotation of the pump 4. This is the flow rate of refrigerant pumped from the pump 4 with respect to speed.

FIG. 2 is a diagram showing refrigerant flow rate characteristics for each of the expander and the pump constituting the exhaust heat regeneration system according to Embodiment 1 of the present invention.
Here, the pressure of the high-pressure side refrigerant from the pump 4 through the evaporator 5 to the expander 2 and the pressure of the low-pressure side refrigerant from the expander 2 through the condenser 3 to the pump 4 are constant conditions. It has become. The pressure of the refrigerant on the high pressure side is 2.6 MPa, the pressure of the refrigerant on the low pressure side is 0.8 MPa, and the differential pressure between the high pressure side and the low pressure side is 1.8 MPa.

In FIG. 2, the horizontal axis indicates the rotational speed (rpm) of the pump 4 and the expander 2 that are rotated together, and the vertical axis indicates the refrigerant flow rate as mass flow rate (kg / min).
And it measured about the refrigerant | coolant flow rate characteristic of the pump 4 and the expander 2 when each rotational speed of the pump 4 and the expander 2 exists in the range of 700-3000 (rpm).

First, the flow rate characteristic of the refrigerant in the expander 2 will be described.
As shown in FIG. 2, the refrigerant flow rate that can be properly processed by the expander 2 is approximately proportional to the rotational speed of the expander 2.
However, due to the flow resistance of the refrigerant at the inlet of the expander 2, the amount of increase in the refrigerant flow rate when the rotational speed of the pump 4 increases by the unit speed gradually decreases as the rotational speed increases. .
The refrigerant flow rate that can be properly processed by the expander 2 when the rotation speed is about 700 (rpm) is about 1.8 (kg / min), and is appropriate for the expander 2 when the rotation speed is 3000 (rpm). The refrigerant flow rate that can be processed is about 5.6 (kg / min).

Next, the refrigerant flow rate characteristic of the pump 4 will be described.
The flow rate of the refrigerant pumped from the pump 4 is approximately proportional to the rotational speed of the pump 4.
However, when the rotational speed is increased, the rotational speed of the pump 4 is increased by the unit speed due to the relative decrease in refrigerant leakage from the high pressure discharge side to the low pressure inlet side in the pump 4. The amount of increase in the refrigerant flow rate gradually increases as the rotational speed increases.

  The refrigerant flow rate when the rotation speed is 700 (rpm) is about 0.8 (kg / min), and the refrigerant flow rate when the rotation speed is 3000 (rpm) is about 9.0 (kg / min). It has become.

And when each rotational speed of the pump 4 and the expander 2 is about 2000 (rpm), the refrigerant | coolant flow volume pumped from the pump 4 and the largest refrigerant | coolant flow volume which can be appropriately processed with the expander 2 correspond. Has been.
The difference between the flow rate of the refrigerant pumped from the pump 4 and the maximum refrigerant flow rate that can be appropriately processed by the expander 2 increases as the rotational speed increases from 2000 (rpm).

In the exhaust heat regeneration system 1A, under the condition where the high and low pressures of the Rankine cycle are constant, it is possible to make the refrigerant flow rate fed from the pump 4 coincide with the maximum refrigerant flow rate that can be properly processed by the expander 2. Operation is possible only at a specific rotational speed, here 2000 (rpm).
Hereinafter, the rotational speed of the pump 4 and the expander 2 in which the flow rate of the refrigerant pumped from the pump 4 and the maximum refrigerant flow rate that can be properly processed by the expander 2 coincide with each other will be referred to as the appropriate rotational speed.

  In the exhaust heat regeneration system 1 </ b> A, a reference heat exhaust regeneration system is one that does not have the control function of the flow rate adjustment valve 11, in other words, one that does not have the function of adjusting the flow rate of the refrigerant flowing through the first bypass passage.

A Mollier diagram of the Rankine cycle, which is the thermodynamic cycle of the reference exhaust heat regeneration system, is shown in FIG.
FIG. 3 is a Mollier diagram of the Rankine cycle, which is a thermodynamic cycle of the reference exhaust heat regeneration system, and shows a state where the pump and the expander are rotated at an appropriate rotation speed.

  In FIG. 3, during the Rankine cycle, point a is the state of the refrigerant at the inlet of the pump 4, point b is the state of the refrigerant at the outlet of the pump 4, point c is the state of the refrigerant at the outlet of the evaporator 5, and point d is the expander. It is the state of the refrigerant | coolant in 2 exits.

The refrigerant flows into the pump 4 in the liquid state represented by the point a, is pressurized, and is discharged from the pump 4 into a state represented by the point b, and is sent to the evaporator 5 through the fourth pipe 24. And passes through the evaporator 5. Cooling water heated to 90-100 ° C. by the engine 8 is circulated from the outside to the evaporator 5. The cooling water is cooled by exchanging heat with the refrigerant in the evaporator 5.
Conversely, the refrigerant is heated by absorbing the heat of the cooling water, and becomes a high-pressure vapor at a high temperature close to 100 ° C. represented by point c at the outlet of the evaporator 5 while keeping the pressure constant.

  The high-temperature and high-pressure refrigerant is led to the expander 2 through the first pipe 21, expands when passing through the expander 2, and the pressure is reduced as represented by point d. The steam is reduced in temperature to about 40 ° C. and discharged from the expander 2. At this time, power for rotating the output shaft 7 is generated in the process of expansion of the expander 2. This power is used as a driving force of the pump 4, taken out for driving a car, or converted into electric energy by a generator 30 having a rotor that rotates in conjunction with the output shaft 7, thereby lighting the car. It can be used as a power source.

Then, the refrigerant is introduced from the expander 2 into the condenser 3 through the second pipe 22 and cooled while keeping the pressure constant. As indicated by point a, the refrigerant has a low temperature slightly lower than 30 ° C. It becomes a liquid, is sent from the condenser 3 to the pump 4 through the third pipe 23, is pressurized again by the pump 4, and is discharged. Note that the condenser 3 has a function of cooling the refrigerant by running wind when the automobile is running, a fan (not shown), or the like.
As the refrigerant circulates through the flow path passing through the pump 4, the evaporator 5, the expander 2, and the condenser 3, the state of the refrigerant changes as described above in the Rankine cycle.

Next, the operation when the pump 4 and the expander 2 are rotated at a rotation speed slower than the compatible rotation speed in the exhaust heat regeneration system of the reference example will be described.
FIG. 4 is a Mollier diagram of the Rankine cycle, which is a thermodynamic cycle of the exhaust heat regeneration system of the reference example, and shows a state where the pump and the expander are rotated at a rotational speed slower than the compatible rotational speed.
During the Rankine cycle, point a1 is the state of the refrigerant at the inlet of the pump 4, point b1 is the state of the refrigerant at the outlet of the pump 4, point c1 is the state of the refrigerant at the outlet of the evaporator 5, and point d1 is the outlet of the expander 2 Is the state of the refrigerant.
Moreover, in FIG. 4, the Mollier diagram in case the pump 4 and the expander 2 are rotated with a suitable rotational speed is written together with the dotted line.

The circulation path of the refrigerant is the same as the case where the pump 4 and the expander 2 are rotated at an appropriate rotation speed.
The refrigerant flows into the pump 4 in a state represented by point a1 and is pressurized, and is discharged from the pump 4 in a state represented by point b1. At this time, since the flow rate of the refrigerant pumped from the pump 4 is smaller than the flow rate of the refrigerant that can be properly processed by the expander 2, the pressure of the refrigerant at the outlet of the pump 4 is expanded as shown by the point b1. It will be in the state which fell compared with the case where the machine 2 rotates with a suitable rotational speed. Thereafter, the refrigerant passing through the evaporator 5 is heated by the cooling water of the engine 8 while keeping the pressure constant, and is expressed at a point c1 at the outlet of the evaporator 5, in other words, at the inlet of the expander 2. Thus, it is considered to be high-pressure steam at a high temperature close to 100 ° C.

After that, it is guided to the expander 2 through the first pipe 21 and expands when passing through the expander 2, and the pressure decreases and the temperature decreases to about 50 ° C. as represented by the point d 1. Steam is discharged from the expander 2. Further, the refrigerant is introduced from the expander 2 through the second pipe 22 into the condenser 3 and cooled, returns to the state indicated by the point a1, and is again pressurized and discharged by the pump 4.
The state of the refrigerant changes repeatedly as described above in the Rankine cycle.

Next, the operation when the pump 4 and the expander 2 are rotated at a rotational speed faster than the compatible rotational speed in the exhaust heat regeneration system of the reference example will be described.
FIG. 5 is a Mollier diagram of the Rankine cycle, which is a thermodynamic cycle of the exhaust heat regeneration system of the reference example, and shows a state where the pump and the expander are rotated at a rotational speed faster than the compatible rotational speed.

During the Rankine cycle, point b2 is the state of the refrigerant at the outlet of the pump 4, point c2 is the state of the refrigerant at the outlet of the evaporator 5, and point d2 is the state of the refrigerant at the outlet of the expander 2.
Moreover, in FIG. 5, the Mollier diagram in case the pump 4 and the expander 2 are rotated with a suitable rotational speed is written together with the dotted line.

The circulation path of the refrigerant is the same as the case where the pump 4 and the expander 2 are rotated at an appropriate rotation speed.
The refrigerant flows into the pump 4 in a state represented by the point a and is pressurized, and is discharged from the pump 4 in a state represented by the point b2. At this time, since the flow rate of the refrigerant pumped from the pump 4 is larger than the refrigerant flow rate that can be properly processed by the expander 2, the pressure of the refrigerant at the outlet of the pump 4 is expanded as shown by point b2. The machine 2 is in an increased state as compared with the case where the machine 2 is rotated at an adapted rotational speed.

  Thereafter, the refrigerant passing through the evaporator 5 is heated by the cooling water of the engine 8 while keeping the pressure constant, and is represented by c2 at the outlet of the evaporator 5, in other words, at the inlet of the expander 2. Thus, it is considered as high-pressure steam at a high temperature close to about 100 ° C.

  After that, it is guided to the expander 2 through the first pipe 21 and expands when passing through the expander 2, and the pressure is reduced and the temperature is about 30 ° C. as represented by the point d 2. The steam is lowered and discharged from the expander 2. Further, the refrigerant is introduced from the expander 2 into the condenser 3 through the second pipe 22 and cooled while keeping the pressure constant, whereby the refrigerant returns to the state indicated by point a. The pressure is increased and discharged.

  As described above, when the exhaust heat regeneration system of the reference example is operated at a rotational speed that is higher than the compatible rotational speed of the pump 4 and the expander 2, the pressure of the high-pressure side refrigerant increases, so that the high-pressure refrigerant flows through the device. May be damaged.

  Therefore, in the exhaust heat regeneration system 1A, a part of the refrigerant discharged from the pump 4 is driven to the condenser 3 via the first bypass flow path configured by the first bypass means 10A by driving the flow rate adjusting valve 11. The refrigerant is returned to the evaporator 5 in an amount that can be properly processed by the expander 2.

Hereinafter, the details of the operation of the exhaust heat regeneration system 1A will be described.
FIG. 6 is a flowchart for explaining the operation of the exhaust heat regeneration system according to Embodiment 1 of the present invention.
In the initial state, the opening degree of the flow regulating valve 11 is assumed to be half open, for example.
For convenience of explanation, Step 101 to Step 112 are described as S101 to S112 in FIG.

In step 101, the refrigerant a refrigerant flow control means 16, which is input from the output of the first pressure sensor 13 and the first temperature sensor 14, and the pressure P _H of the high-pressure side refrigerant is pumped from the pump 4, the expander 2 The temperature T _HE is obtained.

Here, the upper limit pressure threshold value PH _(MAX) and the upper limit temperature threshold value THE _(MAX) are set as follows.
The upper limit pressure threshold value PH _(MAX) is set in advance in consideration of the pressure resistance of the devices arranged on the high-pressure side of the Rankine cycle, the refrigerant to be used, among the components constituting the exhaust heat regeneration system 1A. The value is set to a value slightly smaller than the allowable maximum pressure.
Further, the upper limit temperature threshold value T _{HE (MAX)} is set in advance in consideration of the upper limit temperature of the lubricant used for the refrigerant to be used, the expander 2 and the like, the pressure resistance of the equipment arranged on the high pressure side, and the like. The value is set to a value slightly smaller than the allowable maximum temperature.

In step 102, the refrigerant flow control means 16, the pressure _{P H} is, determines the upper limit pressure threshold _{P H (MAX)} is greater than.

In step 102, the refrigerant flow control means 16, the pressure _{P H} is, if it is determined that the upper limit pressure threshold _{P H (MAX)} is larger than the opening of the flow control valve 11, a predetermined amount larger as the flow rate control valve 11 , The refrigerant flow rate returning from the outlet side of the pump 4 to the inlet side of the condenser 3 through the first bypass channel is increased by a predetermined amount (step 103), and the process returns to step 101.

In step 102, the refrigerant flow control means 16, the pressure _{P H} is, when not greater than the upper limit pressure threshold _{P H (MAX),} the pressure _{P H} is determined reference pressure from the upper limit pressure threshold _{P H (MAX)} It is determined whether or not the value is smaller than the value obtained by subtracting the value _PN (step 104).
Determination reference pressure value P _N is previously set depending on the type of refrigerant used, the value obtained by subtracting the determined reference pressure value P _N from the upper limit pressure threshold P _{H (MAX)} are preferred as the pressure of the high-pressure side refrigerant range It is set as appropriate so as not to fall below the lower limit. In this embodiment, for example, it is set to 0.1 to 0.5 (MPa).

If the refrigerant flow rate control means 16 determines in step 104 that P _H <(P _{H (MAX)} −P _N ), it determines whether or not the opening degree of the flow rate adjusting valve 11 is minimum (step 105).
If it is determined in step 105 that the opening degree of the flow control valve 11 is the minimum, the process proceeds to step 107.
If it is determined in step 105 that the opening degree of the flow rate adjustment valve 11 is not the minimum, the opening degree of the flow rate adjustment valve 11 is controlled so that the opening degree of the flow rate adjustment valve 11 is reduced by a predetermined amount, and the first bypass flow path. The refrigerant flow rate passing through the outlet side of the pump 4 from the outlet side of the pump 4 to the inlet side of the condenser 3 is reduced by a predetermined amount (step 106), and the process returns to step 101.

In step 107, the refrigerant flow rate control means 16 determines whether or not the temperature T _HE is greater than the upper limit temperature threshold value T _{HE (MAX)} .
If the refrigerant flow rate control means 16 determines in step 107 that the temperature T _HE is greater than the upper limit temperature threshold value T _{HE (MAX)} , the rotational speed of the expander 2 is increased by a predetermined speed (step 108). Return to 101.

If the refrigerant flow rate control means 16 determines in step 107 that the temperature T _HE is not higher than the upper limit temperature threshold value T _{HE (MAX)} , the temperature T _HE becomes (upper limit temperature threshold value T _{HE (MAX)-criteria).} It is determined whether or not the temperature is smaller than (T _N ) (step 109).
The determination reference temperature value _TN is set in advance depending on the type of refrigerant to be used, and the value obtained by subtracting the determination reference temperature value _TN from the upper limit temperature threshold value T _{HE (MAX)} is the refrigerant input to the expander 2. The temperature is appropriately set so as not to fall below the lower limit of the preferred range. In the present embodiment, the determination reference temperature value _TN is set between 10 ° C. and 50 ° C., for example.

In step 109, the refrigerant flow control unit 16 _determines that a _{T HE <T HE (MAX)} -T N, slows the rotational speed of the expander 2 by a predetermined speed (step 110), the step 101 Return.
In the first embodiment, R134a is used as the refrigerant. In this case, the upper limit temperature threshold value T _{HE (MAX)} is set to about 190 ° C. By performing the control of steps 109 and 110, the temperature T _HE does not exceed the upper limit temperature threshold value T _{HE (MAX)} . In addition, the refrigerant is heated by heat exchange with cooling water warmed by the engine. For example, the refrigerant is heated by heat exchange with the exhaust gas of the engine as a heat source exceeding 200 ° C. Even in such a case, since the control in steps 109 and 110 is performed, the temperature T _HE does not exceed the upper limit temperature threshold value T _{HE (MAX)} .

In step 109, the refrigerant flow control means _{16, T HE <T HE (MAX} ) -T N not equal it is determined whether the operation stop command, such as a pump 4 and the expander 2 is output, i.e., circulating refrigerant It is determined whether or not an operation stop command for the drive system to be operated (pump 4, expander 2, condenser 3, etc.) has been output (step 111).
For example, rotation of the pump 4 and the expander 2 outputs an operation stop command for the exhaust heat regeneration system 1A on the condition that the engine 8 is stopped.

  In step 111, if the refrigerant flow rate control unit 16 determines that the operation stop command is not output, the refrigerant flow control unit 16 returns to step 101, determines that the operation stop command is output, in other words, determines that the drive system is stopped. The control of the rotation speed of the expander 2 and the opening degree of the flow rate adjustment valve 11 is finished.

In the exhaust heat regeneration system 1A that operates as described above, when the pump 4 and the expander 2 are rotated at a speed that is faster than the appropriate rotational speed by a predetermined speed, in other words, the refrigerant flow rate that is pumped from the pump 4 is When the refrigerant flow rate is larger than the refrigerant flow rate that is appropriately processed in 2 and the pressure of the refrigerant on the high-pressure side of the Rankine cycle approaches the allowable upper limit pressure and exceeds the upper limit pressure threshold value PH _(MAX) , the following Control is performed.

  That is, the refrigerant flow control means 16 is input to the expander 2 via the evaporator 5 among the refrigerant pumped from the pump 4 based on the output of the pressure sensor 13 provided on the high pressure side of the Rankine cycle. By controlling the opening degree of the flow rate adjusting valve 11 so that the flow rate of the refrigerant approaches a flow rate that can be appropriately processed, the refrigerant returns from the outlet side of the pump 4 to the inlet side of the condenser 3 through the first bypass flow path. Adjust the refrigerant flow rate.

Further, when the refrigerant temperature T _HE input to the expander 2 becomes higher than the upper limit temperature threshold value T _{HE (MAX)} , the refrigerant flow rate control means 16 increases the rotational speed of the expander 2 so that the refrigerant temperature T _HE is increased. When it becomes lower than (upper limit temperature threshold value T _{HE (MAX)} −judgment reference temperature value T _N ), the rotation speed of the expander 2 is controlled so that the temperature of the refrigerant flowing into the expander 2 is the allowable upper limit temperature. Is prevented.

Next, the Mollier diagram of the Rankine cycle, which is the thermodynamic cycle of the exhaust heat regeneration system 1A that operates as described above, will be described.
FIG. 7 is a Mollier diagram of the Rankine cycle, which is a thermodynamic cycle of the exhaust heat regeneration system according to Embodiment 1 of the present invention, and shows a case where the pump and the expander are rotated faster than the compatible rotational speed. .
During the Rankine cycle, point a3 is the refrigerant state at the inlet of the pump 4, point b3 is the refrigerant state at the outlet of the pump 4, point c3 is the refrigerant state at the outlet of the evaporator 5, and point d3 is at the outlet of the expander 2. The state of the refrigerant.
In FIG. 7, the Mollier diagram of the exhaust heat regeneration system of the reference example in which the pump 4 and the expander 2 are rotated faster than the compatible rotational speed and the flow rate of the refrigerant is not adjusted is also shown by dotted lines.

The refrigerant circulation path of the exhaust heat regeneration system 1A is the same as that described for the reference exhaust heat regeneration system.
The refrigerant flows into the pump 4 in a liquid state represented by the point a3, is pressurized, and is discharged from the pump 4 into a state represented by the point b3, and is sent to the evaporator 5 through the fourth pipe 24. And passes through the evaporator 5. At this time, the refrigerant cools the cooling water of the engine 8 that is normally heated to 90 to 100 ° C. by the cooling water of the engine 8, while it is heated by absorbing the heat of the cooling water, and at the outlet of the evaporator 5, It becomes high-temperature and high-pressure steam close to 100 ° C. represented by c3 point.

  Here, in the exhaust heat regeneration system 1A, even when the pump 4 and the expander 2 are integrally driven under the condition that the flow rate of the refrigerant discharged from the pump 4 is larger than the flow rate of the refrigerant that can be properly processed by the expander 2, By returning a part of the refrigerant discharged from the pump 4 to the condenser 3 via the first bypass flow path, the flow rate of the refrigerant flowing into the expander 2 becomes a flow rate that can be appropriately processed by the expander 2. For this reason, in the Rankine cycle, the refrigerant pressure when the state of the refrigerant moves from the point b3 to the point c3, as shown in FIG. 7, is compared with the exhaust heat regeneration system of the reference example in which the flow rate of the refrigerant is not controlled. It can be suppressed.

The high-temperature and high-pressure refrigerant is guided to the expander 2 through the first pipe 21, expands when passing through the expander 2, and the pressure is reduced as represented by point d3. The steam is reduced in temperature to about 40 ° C. and discharged from the expander 2. Similar to the exhaust heat regenerative system for reference, this power is used as a driving force for the pump 4, taken out for driving a car, or is generated by a generator 30 having a rotor rotated in conjunction with the output shaft 7. By converting it as energy, it can be used as a power source for automobile lighting or the like.
For this reason, by using the exhaust heat regeneration system 1A, the energy efficiency of the system including the exhaust heat regeneration system 1A is improved, for example, the fuel efficiency of the automobile is improved.

  Further, the refrigerant is introduced from the expander 2 into the condenser 3 through the second pipe 22 and is cooled while keeping the pressure constant, and then sent to the inlet side of the pump 4, as indicated by point a3. Then, the liquid is returned to a low temperature liquid state. Then, the refrigerant is again pressurized by the pump 4 and discharged.

  The exhaust heat regeneration system 1A according to the first embodiment includes a first bypass flow path that connects a refrigerant flow path from the pump 4 to the evaporator 5 and a refrigerant flow path from the expander 2 to the condenser 3. And a first bypass sensor 10A having a flow rate adjusting valve 11 capable of adjusting the flow rate of the refrigerant flowing through the first bypass flow path, and a first pressure sensor 13 for acquiring information on the pressure of the refrigerant pumped from the pump 4. And a refrigerant flow rate control means 16 for controlling the drive of the flow rate adjustment valve 11 based on the output of the first pressure sensor 13.

By adopting such a configuration, even when the pump 4 and the expander 2 are rotated at a rotational speed faster than the compatible rotational speed, in other words, the amount of refrigerant discharged from the pump 4 is appropriate for the expander 2. Even when the pump 4 and the expander 2 are driven integrally under a condition where the amount of refrigerant to be processed is larger, the output of the first pressure sensor 13 corresponds to the flow rate of the refrigerant that can be properly processed by the expander 2. The following effects can be obtained by controlling the flow rate adjusting valve 11 so that the pressure is changed and returning a part of the refrigerant from the high-pressure side refrigerant flow path to the low-pressure side refrigerant flow path.
That is, the pressure of the high-pressure side refrigerant is suppressed from becoming abnormally high, and the refrigerant flows into the expander 2 at a flow rate that can be processed by the expander 2, thereby preventing damage to the equipment through which the high-pressure side refrigerant flows. it can. Furthermore, it is possible to stably operate the exhaust heat regeneration system 1A that uses exhaust heat from an engine or the like as a drive source for a generator that converts electrical heat into electrical energy.

The refrigerant flow rate control means 16 controls the rotation speed of the expander 2 based on information from the first temperature sensor 14 that acquires information related to the temperature of the refrigerant flowing into the expander 2.
Thereby, it can avoid that the refrigerant | coolant which becomes abnormally high temperature flows into the expander 2, and can operate | use the waste heat regeneration system 1A more stably.

Moreover, in the conventional waste heat utilization apparatus, the high-temperature refrigerant discharged from the expander cannot be processed by the expander is configured to be introduced into the evaporator or the condenser. The amount of heat dissipated in the condenser also increases, necessitating the need to increase the size of the condenser and the evaporator, and the exhaust heat regeneration system itself increases in size.
On the other hand, in the exhaust heat regeneration system 1 </ b> A, the first bypass flow path for adjusting the refrigerant flow rate to the expander 2 is configured to be returned to the condenser 3 from the refrigerant flow path from the pump 4 to the evaporator 5. . For this reason, the amount of heat radiation in the condenser 3 is suppressed, the necessity of increasing the size of the condenser 3 and the evaporator 5 is eliminated, and the exhaust heat regeneration system 1A can be reduced in size.
Moreover, since the temperature rise at the output side of the expander 2 can be prevented, an unexpected decrease in the output of the expander 2 can be prevented, and the expander 2 can be operated stably without reducing the efficiency.

  In the first embodiment, the first pressure sensor 13 has been described as being provided in the fourth pipe 24 so that the pressure of the refrigerant pumped from the pump 4 can be acquired. However, for example, the first pressure sensor 13 may be provided on the first pipe 21 side. The pressure of the high-pressure refrigerant flowing in the refrigerant flow path from the pump 4 to the expander 2 via the evaporator 5 can be regarded as the pressure of the refrigerant pumped from the pump 4, and the first pressure sensor 13 is Even if it is provided on the one pipe 21 side, information on the pressure of the high-pressure refrigerant pumped from the pump 4 can be acquired.

Moreover, the 1st temperature sensor 14 demonstrated as what is provided in the 1st piping 21 so that the temperature of the refrigerant | coolant which flows in into the expander 2 after passing the evaporator 5 can be acquired. However, the first temperature sensor 14 may be provided in the housing 6 or the like, for example. Since the temperature of the housing 6 and the temperature of the refrigerant flowing into the expander 2 have a correlation, the temperature of the refrigerant flowing into the expander 2 can be estimated from the first temperature sensor 14 provided in the housing 6. It is.
Thus, if the 1st temperature sensor 14 can also acquire the information regarding the temperature of the refrigerant | coolant which flows in into the expander 2, an installation place will not be limited.

In the first embodiment, the refrigerant flow rate control means 16 adjusts the rotational speed of the expander 2 based on the output of the first temperature sensor 14. However, the output of the first temperature sensor 14 A configuration for adjusting the rotational speed of the expander 2 based on the above is not necessarily required and may be omitted.
Even in this case, since control is performed to flow into the expander 2 based on the output of the first pressure sensor 13, the pressure of the refrigerant on the high-pressure side is suppressed from becoming abnormally high, and a refrigerant with an appropriate flow rate is obtained. It will flow into the expander 2 and the effect of preventing damage to the equipment through which the high-pressure side refrigerant flows is not lost.

Embodiment 2. FIG.
FIG. 8 is a configuration diagram of an exhaust heat regeneration system according to Embodiment 2 of the present invention.
In FIG. 8, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In FIG. 8, the exhaust heat regeneration system 1B is the same as the exhaust heat regeneration system 1A except that the exhaust heat regeneration system 1B includes a first bypass means 10B instead of the first bypass means 10A.
The configuration of the first bypass means 10B is the same as that of the first bypass means 10A, except that an opening / closing valve 33 as an opening / closing means provided so as to freely open and close the first bypass flow path is provided separately from the flow regulating valve 11. It is.
Here, the flow rate adjusting valve 11 for adjusting the flow rate of the refrigerant generally cannot completely block the flow of the refrigerant.

  Therefore, in the second embodiment, the on-off valve 33 that can completely shut off the first bypass flow path constituted by the first bypass means 10B is provided.

The refrigerant flow control means 16 is such that the pump 4 and the expander 2 are rotated at a speed smaller than the suitable rotation speed, and the amount of refrigerant that can be properly processed by the expander 2 is sufficiently large relative to the discharge amount from the pump 4. In other words, in other words, when it is not necessary to return the refrigerant from the outlet side of the pump 4 to the inlet side of the condenser 3, the on-off valve 33 is closed.
On the contrary, the refrigerant flow rate control means 16 is such that the pump 4 and the expander 2 are rotated at a speed larger than the suitable rotation speed, and the amount of refrigerant properly processed by the expander 2 with respect to the discharge amount from the pump 4 is When it is small, the on-off valve 33 is configured to open.

According to the second embodiment, since the on-off valve 33 capable of completely blocking the first bypass flow path is provided, the flow of the refrigerant that is pumped from the pump 4 and flows through the first bypass flow path is ensured. Can be stopped.
Thus, when the exhaust heat regeneration system 1B is operated under the condition that the refrigerant flow rate control means 16 does not need to return the refrigerant from the outlet side of the pump 4 to the condenser 3, the on-off valve 33 is closed, When the exhaust heat regeneration system 1B is operated under the condition that the first bypass passage is shut off and the refrigerant needs to be returned from the outlet side of the pump 4 to the inlet side of the condenser 3, the on-off valve 33 is opened. Thus, by eliminating the blocking of the first bypass flow path, in addition to the effect of the first embodiment, an effect of improving the operation efficiency of the exhaust heat regeneration system 1B can be expected.

Embodiment 3 FIG.
FIG. 9 is a configuration diagram of an exhaust heat regeneration system according to Embodiment 3 of the present invention.
In FIG. 9, the same reference numerals are given to the same or corresponding parts as those in the first embodiment, and the description thereof is omitted.

In FIG. 9, the exhaust heat regeneration system 1 </ b> C obtains the pressure and temperature of the refrigerant flowing through the second bypass unit 40 provided in parallel with the first bypass unit 10 </ b> A and the third pipe 23 connecting the condenser 3 and the pump 4. In other words, the second pressure sensor 51 provided in the third pipe 23 and the second temperature sensor 52 as a low-pressure side temperature sensor are provided so that the pressure and temperature of the refrigerant input to the pump 4 can be acquired. Yes.
Other configurations of the exhaust heat regeneration system 1C are the same as those of the exhaust heat regeneration system 1A.

  The 2nd bypass means 40 comprises the 2nd bypass flow path which connects between the refrigerant flow path from the pump 4 to the evaporator 5, and the refrigerant flow path from the expander 2 to the condenser 3, A refrigerant tank 41 incorporated in the bypass channel, and second on-off valves 43a and 43b as refrigerant inflow selection means provided to be able to open and close the second bypass channel are provided.

  More specifically, the second bypass means 40 includes a refrigerant tank 41, throttles 42a and 42b, second on-off valves 43a and 43b, and an outlet side of the pump 4 and an inlet side of the condenser 3 through these. The second bypass pipe 45 is connected to the refrigerant tank 41 so that a part of the refrigerant pumped from the pump 4 can be transferred into the refrigerant tank 41.

  The second bypass pipe 45 forms a seventh pipe 45 a that forms a refrigerant flow path from the space in the fourth pipe 24 to the refrigerant tank 41, and a refrigerant flow path that extends from the refrigerant tank 41 to the space in the second pipe 22. And an eighth pipe 45b.

The throttle 42a is incorporated in a part of the seventh pipe 45a so that the refrigerant flow rate of the seventh pipe 45a can be adjusted, and the on-off valve 43a is provided so as to block the refrigerant flow path of the seventh pipe 45a. Yes.
Further, the throttle 42b is incorporated in a part of the eighth pipe 45b so that the refrigerant flow rate of the eighth pipe 45b can be adjusted, and the on-off valve 43b is provided so as to block the refrigerant flow path of the eighth pipe 45b. Yes.

  The second pressure sensor 51 is, for example, a resistance strain cage type pressure sensor, similarly to the first pressure sensor 13, and the second temperature sensor 52 is also, for example, a thermistor or a thermocouple, similarly to the first temperature sensor 14. is there.

  Prior to the start of operation of the exhaust heat regeneration system 1C, the throttles 42a and 42b are adjusted in opening in advance, and are fixed during operation. However, the throttles 42a and 42b may be the same as those of the flow rate adjustment valve 11 so that the refrigerant flow rate control means 16 can appropriately adjust the openings of the throttles 42a and 42b.

  The ROM constituting the refrigerant flow rate control means 16 stores the pressure-saturation temperature characteristics of the refrigerant in advance.

  Here, in the exhaust heat regeneration system 1 </ b> A described in the first embodiment, a part of the refrigerant pressure-fed from the pump 4 is supplied to the inlet of the condenser 3 through the first bypass flow path under the control of the flow rate adjustment valve 11. By appropriately returning to the side, the pressure of the refrigerant flowing into the expander 2 is maintained at an appropriate level.

As can be seen from the comparison between the points a3 and a in the Mollier diagram of FIG. 7, when the pump 4 and the expander 3 are rotated at a rotational speed faster than the adapted rotational speed, the pump 4 and the expansion at the adapted rotational speed. Since the pressure on the high pressure side is lower than when the machine 3 is rotated, the temperature of the refrigerant flowing into the pump 4 is lowered. Due to this, although there is no problem in the operation of the exhaust heat regeneration system 1A, the difference between the refrigerant temperature at the inlet of the pump 4 and the saturation temperature of the refrigerant corresponding to the refrigerant pressure at the inlet of the pump 4 The degree of supercooling represented by
When the degree of supercooling increases, the thermal efficiency of the Rankine cycle when the exhaust heat regeneration system 1A circulates the refrigerant decreases.

  Thus, in the exhaust heat regeneration system 1C of the third embodiment, the refrigerant flow rate control means 16 calculates the degree of supercooling based on the outputs of the second pressure sensor 51 and the second temperature sensor 52. When the degree of supercooling deviates from an appropriate range, the refrigerant flow control means 16 adjusts the amount of refrigerant transferred to the refrigerant tank 41 in a direction to return the degree of supercooling to an appropriate value. Further, the opening degree of the on-off valves 43a and 43b is set.

Specifically, the refrigerant flow control means 16, when the degree of supercooling or larger than the upper limit supercooling degree threshold T _SH, and may become smaller than the lower limit subcooling threshold T _SL, the second bypass means 40 The on-off valves 43a and 43b are opened, and a part of the refrigerant is moved to the refrigerant tank 41 to adjust the degree of supercooling to an appropriate value.

  In addition to this, in the exhaust heat regeneration system 1C, the pressure on the high pressure side in the Rankine cycle is controlled in the same manner as in the exhaust heat regeneration system 1A so as not to exceed the allowable upper limit pressure.

Hereinafter, the details of the operation of the exhaust heat regeneration system 1C will be described.
FIG. 10 is a flowchart for explaining the operation of the exhaust heat regeneration system according to Embodiment 3 of the present invention.

In steps 201 to 210, the refrigerant flow rate control means 16 controls the rotational speeds of the flow rate adjustment valve 11 and the expander 3 based on the outputs of the first pressure sensor 13 and the first temperature sensor 14. Since it is the same as step 101 to step 110 of the first embodiment, description thereof is omitted.
The on-off valves 43a and 43b are closed in the initial state.

In step 211, the refrigerant flow rate control means 16 acquires the pressure P _L and the temperature T _LP of the low-pressure side refrigerant flowing into the pump 4 from the outputs of the second pressure sensor 51 and the second temperature sensor 52.

In step 212, the refrigerant flow rate control means 16 obtains the refrigerant saturation temperature _TL at the pressure P _L from the pressure-saturation temperature characteristic.

In step 213, the refrigerant flow control unit 16 calculates the degree of supercooling _{ΔT (= T LP -T L)} , subcooling [Delta] T is, than the upper limit subcooling threshold _{T SH} set in advance, whether a large Is determined (step 213).
The upper limit supercooling degree threshold value _TSH is set to a value slightly smaller than the maximum value in the range of appropriate supercooling degree. For example, the upper limit supercooling degree threshold value T _SH is set to about 10 ° C.

In step 213, the refrigerant flow control means 16, subcooling ΔT is, when it is determined that the upper limit is greater than the subcooling degree threshold T _SH, opening the on-off valve 43a, a part of the refrigerant pumped from the pump 4, the The refrigerant is transferred to the refrigerant tank 41 through the seven pipe 45a, the throttle 42a, and the on-off valve 43a (step 214), and the control returns to step 211.

In step 213, the refrigerant flow control means 16, subcooling ΔT is, when it is determined that the upper limit supercooling threshold _{T SH} smaller, closed-off valve 43a (step 215), the process proceeds to step 216.

In step 216, the refrigerant flow control means 16, the degree of supercooling ΔT _{(= T} LP -T _L) determines whether or not the lower limit subcooling threshold _{T SL} is less than or a preset. The lower limit supercooling degree threshold value _TSL is set to a value slightly larger than the minimum value in the appropriate range of supercooling degree. For example, the lower limit supercooling degree threshold value T _SL is set to about 5 ° C.

In step 216, the refrigerant flow control means 16, subcooling ΔT is, determines that the lower limit supercooling threshold _{T SL} smaller than opening the on-off valve 43 b (step 217), returns to step 211.
In step 216, the refrigerant flow control means 16, subcooling ΔT is, determines that the lower limit is greater than the subcooling degree threshold _{T SL,} closed-off valve 43 b (step 218), the process proceeds to step 219.
Steps 219 and 220 are the same control operations as steps 111 and 112.

Next, the Mollier diagram of the Rankine cycle, which is the thermodynamic cycle of the exhaust heat regeneration system 1C operating as described above, will be described.
FIG. 11 is a Mollier diagram of the Rankine cycle, which is a thermodynamic cycle of the exhaust heat regeneration system according to Embodiment 3 of the present invention, and shows a case where the expander is rotated at a speed faster than the adapted rotational speed.
During the Rankine cycle, point a4 is the inlet of the pump 4, point b3 is the outlet of the pump 4, point c is the outlet of the evaporator 5, and point d4 is the state of the refrigerant at the outlet of the expander 2.
Moreover, in FIG. 11, the Mollier diagram of the Rankine cycle which is a thermodynamic cycle of the exhaust heat regeneration system 1A is shown with a dotted line.

  In the Rankine cycle of the exhaust heat regeneration system 1C shown in FIG. 11, the refrigerant flowing into the pump 4 in the liquid state is increased in pressure as shown in the point a4, as shown in the point a4. It is discharged from the outlet. Further, the refrigerant is guided to the evaporator 5 through the fourth pipe 24 and passes through the evaporator 5. At this time, the refrigerant is heated by the cooling water of the engine 8 while keeping the pressure constant, and becomes high-temperature and high-pressure steam at a high temperature close to 100 ° C. represented by the point c3 at the outlet of the evaporator 5.

  The high-temperature and high-pressure refrigerant is guided to the expander 2 through the first pipe 21, expands when passing through the expander 2, and the pressure is reduced as represented by point d4. The steam is reduced in temperature to about 40 ° C. and discharged from the expander 2. Further, the refrigerant is introduced from the expander 2 through the second pipe 22 into the condenser 3, reaches the inlet side of the pump 4, and is expressed at point a4 while keeping the pressure constant. Return to cold liquid state.

  Here, in FIG. 11, the refrigerant temperature at the inlet of the pump 4, as indicated by points a <b> 3 and a <b> 4, as compared to the case of the exhaust heat regeneration system 1 </ b> A that does not perform refrigerant flow control by the second bypass unit 40. However, although there is almost no change, the pressure of the refrigerant at the inlet of the pump 4 is reduced. Thereby, the degree of supercooling becomes a small and appropriate value.

According to the third embodiment, the refrigerant flow rate control means 16 controls the rotational speeds of the flow rate adjustment valve 11 and the expander 3 based on the outputs of the first pressure sensor 13 and the first temperature sensor 14. Is the same as in the first embodiment.
Accordingly, similarly to the exhaust heat regeneration system 1A, the pressure of the high-pressure side refrigerant is suppressed from becoming abnormally high, and an appropriate flow rate of refrigerant flows into the expander 2, so that the high-pressure side refrigerant flows through the device. Damage can be prevented.

Further, based on the saturation temperature T _{L of the} refrigerant corresponding to the output of the second pressure sensor 51 and the output of the second temperature sensor 52, the opening and closing valves 43a and 43b as the refrigerant inflow selection means open and close the second bypass flow path. And the refrigerant flow rate control means 16 controls the refrigerant flow into the refrigerant tank 41, so that the degree of supercooling ΔT is maintained at an appropriate value.
Thereby, the operating efficiency of the exhaust heat regeneration system 1C can be improved.

Embodiment 4 FIG.
FIG. 12 is a configuration diagram of an exhaust heat regeneration system according to Embodiment 4 of the present invention.
In addition, the same code | symbol is attached | subjected to the same or equivalent part as the said Embodiment 1-3, and the description is abbreviate | omitted.
In FIG. 12, the exhaust heat regeneration system 1D is the same as that of the above-described third embodiment, except that the first bypass unit 10B is provided instead of the first bypass unit 10A.
That is, the opening / closing valve 33 as the first opening / closing means provided so as to be openable / closable is provided separately from the flow rate adjusting valve 11.
The on-off valve 33 is provided for the purpose of completely blocking the one bypass flow path formed by the first bypass means 10B.
The refrigerant flow rate control means 16 controls the on-off valve as in the second embodiment.

  According to the exhaust heat regeneration system 1D of the fourth embodiment, the on-off valves 43a and 43b have the second bypass means 40, and the refrigerant flow rate control means 16 takes an appropriate value for the degree of supercooling ΔT. The point of performing the open / close control is the same as that of the third embodiment, and the operation efficiency of the exhaust heat regeneration system 1D can be improved.

Further, according to the fourth embodiment, since the on-off valve 33 capable of completely blocking the first bypass flow path constituted by the first bypass means 10B is provided, the refrigerant flowing through the first bypass flow path is provided. The flow can be stopped reliably.
When the exhaust heat regeneration system 1D is operated under the condition that the refrigerant does not need to be returned to the condenser 3 from the outlet side of the pump 4, the on-off valve 33 is closed to shut off the first bypass flow path, and the pump When the exhaust heat regeneration system 1D is operated under the condition that the refrigerant needs to be returned to the condenser 3 from the outlet side of the outlet 4, the on-off valve 33 is opened so as to cancel the blockage of the first bypass flow path. By making the refrigerant flow rate control means 16 control the operation efficiency of the exhaust heat regeneration system 1D can be improved.

Embodiment 5 FIG.
FIG. 13 is a block diagram of an exhaust heat regeneration system according to Embodiment 5 of the present invention.
In FIG. 13, the exhaust heat regeneration system 1 </ b> E is configured in the same manner as the exhaust heat regeneration system 1 </ b> C except that the first bypass means 10 </ b> C is provided instead of the first bypass means 10 </ b> A.

  The first bypass means 10C constitutes a first bypass flow path connecting the refrigerant flow path from the pump 4 to the evaporator 5 and the refrigerant flow path from the condenser 3 to the inlet side of the pump 4, and the first bypass means 10C. 1 It has the flow control valve 11 which can adjust the flow volume of the refrigerant | coolant which flows through a bypass flow path.

Specifically, the first bypass means 10 </ b> C includes a flow rate adjustment valve 11, a bypass pipe 12 </ b> B that connects the inside of the fourth pipe 24 and the inside of the third pipe 23 via the flow rate adjustment valve 11, and the first bypass flow path. And an open / close valve 33 that can be freely opened and closed.
The first bypass pipe 12B includes a ninth pipe 12c that forms a refrigerant flow path from the space in the fourth pipe 24 to the flow rate adjustment valve 11, and a refrigerant flow path from the flow rate adjustment valve 11 to the space in the third pipe 23. And a tenth pipe 12d.
And the on-off valve 33 is provided in the 10th piping 12d so that the refrigerant | coolant flow path of the 10th piping 12d can be opened and closed freely.

By controlling the flow rate adjusting valve 11 of the first bypass means 10C, it is possible to adjust the amount of refrigerant that is pumped from the pump 4 and led to the inlet side of the pump 4 through the first bypass flow path. ing.
The drive control of the flow rate adjustment valve 11 and the control of the on-off valve 33 by the refrigerant flow rate control means 16 are performed in the same manner as in the first and second embodiments.

That is, when the refrigerant flow rate pumped from the pump 4 is larger than the refrigerant flow rate appropriately processed by the expander 2, the following control is performed.
Based on the output of the first pressure sensor 13, the refrigerant flow rate control means 16 determines that the refrigerant pressure on the high-pressure side of the Rankine cycle has approached the upper limit of the allowable upper limit and has exceeded the upper limit pressure threshold value PH _(MAX). When the determination is made, as in the first embodiment, the opening of the flow rate adjusting valve 11 and the on-off valve 33 are set so that the amount of the refrigerant flowing into the first bypass flow path becomes an appropriate flow rate of the refrigerant flowing into the expander 2. Controls the opening and closing of.

Here, the first bypass means 10A, 10B of the first to fourth embodiments constitute the first bypass flow path from the outlet of the pump 4 to the inlet side of the condenser 3. The 1 bypass means 10 </ b> C constitutes a bypass flow path from the outlet side of the pump 4 to the inlet side of the pump 4.
However, the first bypass flow path connects the high-pressure side refrigerant flow path from the pump 4 to the evaporator 5 and the low-pressure side refrigerant flow path from the expander 2 to the pump 4 via the condenser 3. This is common to the first to fourth embodiments.
For this reason, also in Embodiment 5, the same effect as Embodiment 1 is acquired.

In the fifth embodiment, the bypass means 10C is applied in place of the first bypass means 10A in the exhaust heat regeneration system 1D. However, in the exhaust heat start exhaust heat regeneration system 1A, the first bypass means 10A is replaced with the first bypass means 10A. Instead, the first bypass means 10C may be applied.
That is, the first bypass means connects the refrigerant flow path from the pump 4 to the expander 2 via the evaporator 5 and the refrigerant flow path from the expander 2 to the pump 4 via the condenser 3. What is necessary is just to provide so that one bypass flow path may form.
Moreover, although the bypass means 10C has the on-off valve 33, the on-off valve 33 may be omitted.

  In each of the above embodiments, the rotating electrical machine is described as being the generator 30, but the rotating electrical machine may be an electric motor. That is, the exhaust heat regeneration systems 1 </ b> A to 1 </ b> E are not limited to those that use the exhaust heat of the engine 8 as power for driving the generator 30. For example, the output of the electric motor is used as part of the engine power source. In this way, the electric motor and the engine 8 may be connected so that the exhaust heat of the engine 8 is used as power for driving the engine or the like.

  1A to 1E Waste heat regeneration system, 2 expander, 3 condenser, 4 pump, 5 evaporator, 7 output shaft, 10A to 10C first bypass means, 11 flow rate adjustment valve (flow rate adjustment means), 13 first pressure sensor , 14 First temperature sensor (high pressure side temperature sensor), 16 Refrigerant flow rate control means, 40 Second bypass means, 41 Refrigerant tank, 43a, 43b Refrigerant inflow selection means, 51 Second pressure sensor, 52 Second temperature sensor (low pressure) Side temperature sensor).

Claims (4)

An expander that expands the refrigerant to generate a driving force;
A condenser for condensing the refrigerant from the expander;
A pump that is coupled to the expander via an output shaft so that the driving force of the expander is transmitted, and that pumps the refrigerant from the condenser;
An exhaust heat regeneration system comprising an evaporator that heats the refrigerant from the pump and sends it to the expander,
Forming a first bypass channel connecting the refrigerant channel from the pump to the evaporator and the refrigerant channel from the expander to the pump via the condenser; First bypass means having flow rate adjusting means capable of adjusting the flow rate of the refrigerant flowing through the flow path;
A first pressure sensor for acquiring information on the pressure of the refrigerant pumped from the pump;
An exhaust heat regeneration system comprising: a refrigerant flow rate control unit that controls driving of the flow rate adjustment unit based on an output of the first pressure sensor. A refrigerant tank that configures a second bypass channel that connects a refrigerant channel from the pump to the evaporator and a refrigerant channel from the expander to the condenser, and is incorporated in the second bypass channel And a second bypass means having a refrigerant inflow selection means provided to open and close the second bypass flow path,
A second pressure sensor for acquiring information on the pressure of the refrigerant guided from the condenser to the pump;
A low-pressure side temperature sensor that acquires information on the temperature of the refrigerant guided from the condenser to the pump;
The refrigerant flow rate control means opens and closes the second bypass flow path by the refrigerant inflow selection means based on the saturation temperature of the refrigerant corresponding to the output of the second pressure sensor and the output of the low temperature side temperature sensor. The exhaust heat regeneration system according to claim 1, wherein the exhaust heat regeneration system controls the flow of the refrigerant into the refrigerant tank. A high-pressure side temperature sensor that obtains information on the temperature of the refrigerant guided from the evaporator to the expander;
The exhaust heat regeneration system according to claim 1 or 2, wherein the refrigerant flow rate control means controls the rotational speed of the expander based on an output of the high pressure side temperature sensor. An opening / closing means capable of fully closing the first bypass flow path;
The exhaust heat regeneration system according to any one of claims 1 to 3, wherein the refrigerant flow rate control means controls opening and closing of the opening and closing means based on an output of the first pressure sensor. .

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