JP3389751B2 - Exhaust energy recovery device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust energy recovery apparatus for recovering energy by rotating a rotating electric machine provided in a turbocharger by using exhaust gas. [0002] In a turbocharger of a turbo car, a turbine is rotated by exhaust gas to promote the suction of the atmosphere. However, the exhaust gas after starting the vehicle and shifting to normal running rotates the turbine. Even after being let go, it still has enough energy. Therefore, a device has been considered in which a rotating electric machine is attached to a turbocharger and the exhaust energy is further recovered. FIG. 8 is a diagram showing a configuration of such an exhaust energy recovery device. 8, 1 is a vehicle generator, 11 is a turbocharger rotating electric machine, 11-1 is a rotor, 11-2 is a stator, 13 is a battery, 20 is a pulley, 21 is an engine, 22 is an intake pipe, and 23 is Exhaust pipe, 2
4 is a belt, 25 is a pulley, 26 is a turbocharger,
27 is a compressor blade, 28 is a turbine blade, and 29 is an electric load. The pulley 20 is connected to the shaft of the engine 21, and the pulley 25 is connected to the shaft of the vehicle generator 1. The pulleys 20 and 25 are connected by a belt 24. The turbocharger rotating electric machine 11 is provided in the turbocharger 26, and its rotor 1
1-1 is connected to the rotating shafts of the compressor blade 27 and the turbine blade 28 of the turbocharger 26, and the stator 11-2 is fixed inside the turbocharger 26. As the turbocharger rotating electric machine 11, a synchronous machine is used, and as described below, the generator is operated or the motor is operated as occasion demands. The electric power generated by the vehicle generator 1 is used to charge the battery 13 and supply power to the electric load 29, as is well known, but when the turbocharger 26 has a weak turbo action (the boost pressure is still small) at the time of starting. For example, power is also supplied to the turbocharger rotating electric machine 11. The turbocharger rotating electric machine 11 supplied from the vehicle generator 1 operates as a motor, assists the rotation of the compressor blade 27 and the turbine blade 28, promotes the turbo action, and increases the engine torque. When the energy of the exhaust gas is large, the turbocharger rotating electric machine 11 is operated by a generator, and the generated electric power is used to charge the battery 13 or to charge the electric load 2.
9 for power supply. In some cases, it is also supplied to the vehicle generator 1, and the vehicle generator 1 is driven by a motor.
The motor generator-driven vehicle generator 1 applies torque to the engine 21 to reduce fuel consumption. FIG. 9 is a block diagram of a conventional exhaust energy recovery device. Reference numerals correspond to those in FIG. 8, 2 is an inverter rectifier circuit, 3 is a rectifier circuit, 4 is an inverter, 5
Is a smoothing circuit, 6 is a booster circuit, 7 is a smoothing circuit, 8 is an inverter rectifier circuit, 9 is an inverter, 10 is a rectifier circuit, 11
Is a turbocharger rotating electric machine, 12 is a position sensor, 14 is a regulator, 15 is a switching circuit, and 16 is a control unit. [0007] The booster circuit 6 boosts and applies the generated voltage of the vehicle generator 1 when the turbocharger rotating electric machine 11 is driven by a motor. Generally, the rotation speed of the turbocharger rotating electric machine 11 is higher than that of the vehicle generator 1, and the induced voltage thereof is higher. In order to operate the turbocharger rotating electric machine 11 with a motor, it is necessary to apply a voltage higher than the induced voltage, but the generated voltage of the vehicle generator 1 may not reach that value. Therefore, the voltage is boosted by the booster circuit 6 and applied. The configuration of the booster circuit 6 is a known booster circuit using a switching transistor. The inverter rectifier circuits 2 and 8 are circuits that at one time perform the role of an inverter and at other times perform the role of a rectifier circuit. One example of the configuration is shown in FIG. 3 (parts indicated by reference numerals 2 and 8) described later. The position sensor 12 is a sensor that detects a magnetic pole position of a rotor of the turbocharger rotating electric machine 11 that is a synchronous machine.
The number of rotations can also be detected based on the signal from the position sensor 12. The control unit 16 receives signals from the position sensor 12 as well as vehicle information (eg, accelerator opening, engine speed, etc.) from various sensors and switches. Then, as shown by the dotted line, the control circuit issues a signal for controlling the inverter rectifier circuit 2, the booster circuit 6, the inverter rectifier circuit 8, and the regulator 14. The generated voltage of the vehicle generator 1 is rectified by the rectifier circuit 3, smoothed by the smoothing circuit 5, and
The output voltage V _P to appear. Similarly, when the turbocharger rotating electric machine 11 performs a power generation operation, the generated voltage is rectified by the rectification circuit 10, smoothed by the smoothing circuit 7, and
The output voltage _VQ appears at the right. The output voltage V _P of each smoothing circuit,
V _Q is input to the switching circuit 15, the higher voltage of which is selected and output to the regulator 14. The regulator 14 controls the voltage from the switching circuit 15 to a voltage suitable for charging the battery 13 or supplying power to an electric load. Its configuration is, for example, a switching transistor,
It is a known device including a transformer, a rectifying / smoothing circuit, and the like (see a portion indicated by reference numeral 14 in FIG. 3 described later). FIG. 2 is a diagram showing a region where a torque increase is required and an energy recovery region in the engine. The horizontal axis represents the engine speed, and the vertical axis represents the turbocharger speed. The rotation speed of the vehicle generator 1 is determined by the engine rotation speed and the rotation speed ratio of the pulleys 20 and 25.
A curve a indicates a change in the turbocharger rotation speed when the turbocharger rotating electric machine 11 is not operated by the motor or the power generation operation. The torque increase required area A, which is indicated as an area where the engine speed is lower than N _1, is an area where the boost pressure is low and the engine torque is low only when the turbocharger 26 is rotated only by the energy of the exhaust gas. It is. In this region, a torque increase is required. Engine speed N ₁ is different depending on the type of engine (e.g., 900 rpm). The curve B shows a change when the turbocharger rotating electric machine 11 is driven by a motor to increase the torque and the turbocharger rotation speed is increased. When the turbocharger rotating electric machine 11 is driven by a motor, the electric power generated by the vehicle generator 1 is supplied through a route of the rectifier circuit 3 → the smoothing circuit 5 → the booster circuit 6 → the inverter 9 → the turbocharger rotating electric machine 11. The energy recovery region B, which is indicated as a region where the engine speed is higher than N _2, is a region where the boost pressure becomes unnecessarily high when the turbocharger 26 is rotating with the energy of the exhaust gas. And
In this region, extra energy can be recovered. Engine speed N ₂ depends on the type of engine (e.g., 1300 rpm). A curve C shows a change when the turbocharger rotating electric machine 11 is operated as a generator for energy recovery and the turbocharger rotation speed is reduced. The power generated by the turbocharger rotating electric machine 11 is supplied to the rectifier circuit 10 → smoothing circuit 7 → switching circuit 15 → regulator 1
4 and a rectifier circuit 10 → smoothing circuit 7 → inverter 4 →
There is also a case where the electric power is supplied to the vehicle generator 1 through the route of the vehicle generator 1. Thus, the energy of the exhaust gas is recovered as electrical energy and mechanical energy. Conventional documents relating to the exhaust energy recovery device include, for example, Japanese Patent Application Laid-Open No. 5-152919,
There is JP-A-3-222695. [0017] The above-mentioned prior art has the following problems. The first problem is that the step-up circuit 6 needs to be provided in order to motor-operate the turbocharger rotating electric machine 11 with the electric power generated by the vehicle generator 1, which increases the cost and requires the installation space. It is. The second problem is that when the generated voltage of the turbocharger rotating electric machine 11 is lower than the generated voltage of the vehicle generator 1, the vehicle generator 1 cannot be driven by a motor. An object of the present invention is to solve such a problem. In order to solve the above-mentioned problems, an exhaust energy recovery apparatus according to the present invention is provided with a vehicle generator and a turbocharger. The turbocharger rotating electric machine that is driven and the generator is operated when the energy of the exhaust gas is large, and is provided corresponding to each of the vehicle generator and the turbocharger rotating electric machine. An inverter rectifier circuit that is operated as an inverter and operates as a rectifier circuit or a step-up chopper when operating a generator; Circuit, a current sensor for detecting a current of each of the smoothing circuits, the vehicle generator and a turbocharger. When the current flowing into the smoothing circuit on the motor operating side of the rotating electric machine does not reach a predetermined value, the control means controls the voltage of the inverter rectifier circuit on the generator operating side. (Summary of operation to be solved) In an exhaust energy recovery apparatus provided with a turbocharger rotating electric machine in addition to a vehicle generator, an inverter rectifier circuit provided corresponding to the vehicle generator and the turbocharger rotating electric machine Is operated as an inverter when performing DC / AC conversion, and is operated as a rectifier circuit or a step-up chopper when performing AC / DC conversion. If the generated voltage is lower than the induced voltage of the other party operating the motor, it is operated as a boost chopper and raised. By using the inverter rectifier circuit in this way, it is not necessary to provide a dedicated booster circuit. Also, if necessary, the voltage generated by the turbocharger rotating electric machine can be increased, and the vehicle generator can be driven by a motor. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of the exhaust energy recovery apparatus of the present invention, and the reference numerals correspond to those of FIG. 17 is a boost pressure sensor, 18
Is an engine speed sensor, 19 is an accelerator opening sensor,
Reference numerals 30 and 31 are current sensors. The first point of the configuration, which is different from the conventional example of FIG. 9, is that the booster circuit 6 is eliminated. The second point is that current sensors 30 and 31 for detecting the current on the DC side of the smoothing circuits 5 and 7 are provided. The third point is that the switching circuit 15 is also eliminated. Since the boost pressure detection signal, the engine speed signal, and the accelerator opening are included in various "vehicle information" input to the control unit 16 in the conventional example of FIG. Boost pressure sensor to detect,
Although there were an engine speed sensor, an accelerator opening sensor, and the like, detection signals from these sensors are also related to the control operation of the present invention, and therefore, they are particularly illustrated in FIG. Although the configuration of the inverter rectifier circuits 2 and 8 is the same as that of the conventional example shown in FIG. 9, the present invention is different in the way of use when converting from AC to DC. That is, when processing the generated voltage of the generator connected to the AC side of the inverter rectifier circuit (for example, the vehicle generator 1 for the inverter rectifier circuit 2), only the rectifier circuit portion is used as in the related art. In some cases, only rectification is performed, and in other cases, a rectifier circuit and an inverter are used in combination to operate as a step-up chopper. The boost chopper operation is performed in the following case. In other words, a voltage obtained by simply rectifying and smoothing the generated voltage is a case where the voltage is lower than the smoothed voltage from the other generator, and this is performed when it is desired to supply power to the other generator or the regulator 14 from this side. When a voltage higher than the induced voltage of the other generator is applied, the other generator can be operated by a motor. Also, among the smoothed voltage V _P, V _Q, if one is higher than the other is boosted, is fed from the side of one said to the regulator 14. Regulator 14 by boost
Since the power supply to the power supply can be determined, the switching circuit 15 becomes unnecessary. FIG. 3 is a diagram showing a specific circuit of the exhaust energy recovery apparatus of the present invention, and the reference numerals correspond to those of FIG. Then, 14-1 are switching transistors, L _A, L _T is a reactor. The inverter rectifier circuits 2 and 8 are known circuits each including a three-phase bridge-connected switching element (eg, a transistor) and a diode connected in anti-parallel to the switching element. This circuit is
The DC voltage applied from the DC terminal side can be converted into an AC voltage, and the AC voltage (power generation voltage) applied to the AC side can be converted (rectified) into a DC voltage. However, in the present invention, a method of operating the inverter rectifier circuits 2 and 8 as a step-up chopper in a specific case using a reactor existing on the AC side is also used. Next, a boost chopper will be described using the inverter rectifier circuit 2 as an example. FIG. 4 is a diagram showing the connection relationship between the inverter rectifier circuit 2 and the stator winding of the vehicle generator 1. The reference numerals correspond to those in FIG.
Reference numerals -1 and 2-2 denote transistors which are switching elements for a certain phase, reference numerals 2-3 and 2-4 denote diodes connected in anti-parallel to the transistors, and reference numerals 2-5 and 2-6 denote terminals. . When operating as a step-up chopper, of the switching transistors constituting the inverter rectifier circuit 2, the switching transistors connected in the direction in which the generated current flows are on-off controlled to perform chopping. The other switching transistor is kept off. For example, with respect to the generated current from the stator winding 1-1, the transistor 2-2 connected in the direction in which the current flows is controlled to be on and off, and the other transistor 2-1 is kept off. Then, a current I ₁ flows during on of the transistor 2-2, a current flows I ₂ through the diode 2-3 during off. FIG. 5 is a diagram showing an example of a circuit portion operating as a step-up chopper. Symbols correspond to those in FIG. 4, 2-7 and 2-8 are terminals, V _IN is an input voltage,
V _OUT is the output voltage. A known boost chopper using a switching transistor requires a reactor for storing electromagnetic energy on the input side, but the stator winding 1-1 for generating a voltage also functions as the reactor. If the shortage still occurs, as shown in FIGS. 3 and 4, the vehicle generator 1 and the inverter rectifier circuit 2
The reactor L _A may be connected to each of the phase lines between the two. (The reactor L _{T in} FIG. 3 can also be connected for the same reason as for the turbocharger rotating electric machine 11. The transistor 2 During the period when -2 is turned on,
Current I ₁ flows through a path shown by dashed-line arrow. The off time period, the electromagnetic energy stored in the stator winding 1-1 in the period of ON, the current I ₂ flows in the path indicated by dotted arrows. FIG. 6 is a waveform diagram of the current and the like of the step-up chopper of FIG. FIG. 6A shows a switching signal for turning on and off the transistor 2-2. The switching frequency of this signal is much higher than the frequency of the generated voltage from the vehicle generator 1 (eg, about the carrier frequency). Then, the change in the generated voltage in a short time of one cycle of the switching signal is extremely small, and the input voltage V _IN during that time can be considered almost the same as the DC voltage. FIGS. 6B and 6C show the currents I ₁ and I ₂ , and FIG.
_Shows the waveform of the output voltage V _OUT . The output voltage V _OUT output from the inverter rectifier circuit 2 is smoothed by the smoothing circuit 5 in FIG. FIG. 7 is a flowchart for explaining the control operation in the present invention. Step 1: It is checked whether or not the turbocharger rotating electric machine 11 is to be operated by a motor. As a case where the motor operation is required, for example, there is a case where the operating condition of the engine is in the torque increase required region in FIG. Whether it is in that area is determined based on the engine speed detected by the engine speed sensor 18. Step 2: If the turbocharger rotating electric machine 11 is to be operated by a motor, a current for operating the motor must flow from the DC side of the inverter rectifier circuit 8. Therefore, the current is detected by the current sensor 31 in FIG. Step 3: It is checked whether or not the detected current from the current sensor 31 is smaller than the current to be passed to the turbocharger rotating electric machine 11 (motor operation instruction current). Note that the motor operation instruction current for the turbocharger rotating electric machine 11 is a current necessary to attain a desired motor operation state at this time. The motor operating state desired at this time is determined by a differential pressure between a boost pressure desired in the current operating state of the engine (hereinafter, referred to as “target boost pressure”) and an actual boost pressure detected by the boost pressure sensor 17. . The target boost pressure differs according to the engine speed and the accelerator opening, which are factors that define the operation state of the engine, and is obtained in advance and stored as a map. The target boost pressure can be obtained by operating the turbocharger rotating electric machine 11 by a motor and increasing the boost pressure by the differential pressure. The current required for operation is the motor operation instruction current. Step 4: If the current detected by the current sensor 31 is smaller than the motor operation instruction current (including the case where the direction of the current is reversed), the DC current flowing into the inverter rectifier circuit 8 is increased. Then, the inverter rectifier circuit 2 on the power supply side is operated as a boost chopper. Step 5: The ON period of the boost chopper is increased to increase the boost voltage. Step 6: If the detected current is larger than the motor operation instruction current in Step 3, it is checked whether or not the inverter rectifier circuit 2 is already operating as a step-up chopper. If not (if only a rectifying operation is being performed), the process proceeds to step 8. Step 7: If the boost chopper is operating, the ON period is reduced. Step 8: The inverter rectifier circuit 8 performs an inverter operation for converting DC to AC, and supplies a motor operating current to the turbocharger rotating electric machine 11. Step 9: If it is not the case that the turbocharger rotating electric machine 11 is operated by the motor in the step 1, it is checked whether or not the vehicle generator 1 is operated by the motor. The case where it is necessary to drive the vehicle generator 1 with a motor includes, for example, a case where there is a large amount of exhaust energy (a case where the operation state of the engine is in the energy recovery region in FIG. 2). If the vehicle generator 1 does not need to be driven by a motor, the process proceeds to the end. Step 10: If the vehicle generator 1 is to be operated by a motor, a current for operating the motor must flow from the DC side of the inverter rectifier circuit 2. Therefore, the current is detected by the current sensor 30 in FIG. Step 11: It is checked whether or not the detected current from the current sensor 30 is smaller than the current to be supplied to the vehicle generator 1 (motor operation instruction current). The vehicle generator 1
Is a current necessary for bringing the motor into a desired operating state at this time. The desired motor operating state at this time is determined by the differential pressure between the target boost pressure in the current operating condition of the engine and the actual boost pressure detected by the boost pressure sensor 17. If the turbocharger rotating electric machine 11 is operated by the generator with the energy corresponding to the differential pressure, the turbo action is reduced and the target boost pressure is obtained. Therefore, the current that can flow through the vehicle generator 1 is determined by the differential pressure, and this current becomes the motor operation instruction current. Step 12: If the current detected by the current sensor 30 is smaller than the motor operation instruction current (including the case where the direction of the current is reversed), the DC current flowing into the inverter rectifier circuit 2 is increased. Then, the inverter rectifier circuit 8 on the power supply side is operated as a boost chopper. Step 13: The ON period of the boost chopper is increased to increase the boost voltage. Step 14: If the detected current is larger than the motor operation instruction current in Step 11, it is checked whether or not the inverter rectifier circuit 8 is already operating as a boost chopper. If not (if only rectifying operation),
Proceed to step 16. Step 15: If the step-up chopper is operating, the ON period is reduced. Step 16: The inverter rectifier circuit 2 is caused to perform an inverter operation for converting DC to AC, and a motor operating current is supplied to the vehicle generator 1. As described above, according to the exhaust energy recovery apparatus of the present invention, the inverter rectifier circuit provided corresponding to the vehicle generator and the turbocharger rotating electric machine converts DC / AC into DC / AC. If so, it is operated as an inverter, and if AC / DC conversion is performed, it is operated as a rectifier circuit or a step-up chopper. Therefore, when one of them is operated by the generator and the other is operated by the motor, if the voltage on the generator operation side is lower than the induced voltage on the motor operation side, the inverter rectifier circuit on the generator operation side operates the boost chopper operation. Can be higher. Therefore, it is not necessary to provide a dedicated booster circuit. Also, if necessary, boost the generated voltage of the turbocharger rotating electrical machine,
The vehicle generator can also be driven by a motor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an exhaust energy recovery device of the present invention. FIG. 2 is a diagram showing a torque-up required area and an energy recovery area. FIG. FIG. 4 is a diagram showing a circuit. FIG. 4 is a diagram showing a connection relationship between an inverter rectifier circuit and a stator winding of a vehicle generator. FIG. 5 is a diagram showing a circuit portion operating as a step-up chopper. FIG. 7 is a flowchart illustrating a control operation in the present invention. FIG. 8 is a diagram illustrating a configuration of an exhaust energy recovery device. FIG. 9 is a block diagram of a conventional exhaust energy recovery device. Description: 1 ... vehicle generator, 2 ... inverter rectifier circuit, 3 ... rectifier circuit, 4 ... inverter, 5 ... smoothing circuit, 6 ... booster circuit, 7
... Smoothing circuit, 8 ... Inverter rectifier circuit, 9 ... Inverter, 10 ... Rectifier circuit, 11 ... Turbocharger rotating electric machine, 11-1 ... Rotor, 11-2 ... Stator, 12 ... Position sensor, 13 ... Battery, 14 …regulator,
15 switching circuit, 16 control section, 17 boost pressure sensor, 18 engine speed sensor, 19 accelerator opening sensor, 20 pulley, 21 engine, 22 intake pipe, 23 exhaust pipe, 24 Belt, 25 ... pulley, 26
... turbocharger, 27 ... compressor blade, 2
8 Turbine blade 29 Electric load 30, 31
Current sensor

Claims (1)

(57) [Claims] [Claim 1] A vehicle generator and a turbocharger are provided, and a motor is operated when the turbo action is insufficient, and when the energy of exhaust gas is large, A turbocharger rotating electric machine driven by a generator is provided corresponding to each of the vehicle generator and the turbocharger rotating electric machine, and operates as an inverter when the motor is operated, and a rectifier circuit or a rectified circuit when the generator is operated. An inverter rectifier circuit that operates as a boost chopper, and a smoothing circuit that is provided corresponding to each of the inverter rectifier circuits and smoothes a DC output voltage of the inverter rectifier circuit.
A current sensor for detecting a current of each of the smoothing circuits; and a generator operating side when the current flowing into the smoothing circuit on the motor operating side of the vehicle generator and the turbocharger rotating electric machine does not reach a predetermined value. And a control means for controlling the pressure of the inverter rectifier circuit.