JP3389750B2 - 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. 4 is a diagram showing a configuration of such an exhaust energy recovery apparatus. In FIG. 4, 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 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 as a generator, and the generated electric power is used for charging the battery 13 and supplying power to the electric load 29. 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. 5 is a block diagram of a conventional exhaust energy recovery apparatus. Reference numerals correspond to those in FIG. 4, 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 much higher than that of the vehicle generator 1, and the induced voltage is large. Therefore, in order to operate the turbocharger rotating electric machine 11 by motor, it is necessary to apply a voltage larger than the induced voltage, but the generated voltage of the vehicle generator 1 may not reach the 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, 8 are circuits that at one time act as inverters and at other times act as rectifier circuits. The configuration is, for example, a configuration in which diodes are connected in anti-parallel to each of the three-phase bridge-connected switching transistors. 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, the voltage generated by the turbocharger rotating electric machine 11 is rectified by the rectifier circuit 10,
The output voltage V _Q appears at the point Q after being smoothed by the smoothing circuit 7. The output voltages V _P and V _Q of each smoothing circuit are input to the switching circuit 15, and the higher voltage 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 and supplying power to the electric load 29. FIG. 6 shows an example of the configuration of the regulator. 14
-1 is a switching transistor, 14-2 is a transformer,
14-3 is a diode, 14-4 is a smoothing capacitor, 1
4-5 and 14-6 are input terminals. By turning on / off the switching transistor 14-1, the terminal 14
The DC voltage applied to -5 and 14-6 is converted to an AC voltage. The AC voltage is transformed by the transformer 14-2, rectified and smoothed by the diode 14-3 and the smoothing capacitor 14-4, and becomes a flat DC voltage. This is applied to the battery 13 and the electric load 29. FIG. 7 is a diagram showing an area where torque is required and an energy recovery area 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. In the energy recovery area B shown as an area where the engine speed is higher than N ₂ , the boost pressure becomes unnecessarily high when the turbocharger 26 is rotated with the energy of the exhaust gas. This is an area where 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 decreases.
The electric power generated by the turbocharger rotating electric machine 11 is supplied to the battery 13 and the electric load 29 through the route of the rectifier circuit 10 → the smoothing circuit 7 → the switching circuit 15 → the regulator 14, and the rectifier circuit 10 → the smoothing circuit 7 → the 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. When the battery 13 is charged, overcharging is prevented. That is, the battery voltage is detected, and the detected battery voltage is the upper limit of the allowable charging voltage (eg, 2
The regulator 14 is controlled so as not to exceed 7 V). As a conventional document relating to an exhaust energy recovery apparatus, there is, for example, Japanese Patent Application Laid-Open No. 5-141254. [Problems to be Solved] (Problem) In the above-mentioned conventional technology, the battery is charged without any particular difference in charging between normal driving and braking. During braking when there is a lot of energy available, the battery may be in a state where the amount of charge that the battery can accept is small. In such a case,
There was a problem that only a part of the energy was recovered and the remaining energy could not be recovered. (Explanation of the Problem) The limitation on the charging of the battery 13 is limited only when the battery voltage is monitored and the battery 13 is likely to be overcharged. Therefore, the battery 13 may be charged to near full charge during normal driving. However, if the brake is applied in such a state, the battery 13 is immediately generated by the generation of the recovered energy. It will be fully charged. It is restricted not to charge any more (it is made not to take out generated power)
Therefore, despite the energy that can still be recovered,
You will not be able to collect it. The electric power generated by the vehicle generator 1 during normal running is generated by being driven by the engine 3, and the electric power charged thereby is the electric power generated by consuming fuel. Therefore, the energy that can be recovered during braking is not fully utilized, and extra fuel is consumed during normal driving to charge the battery. It can be said that energy is recovered efficiently. Did not. An object of the present invention is to solve such a problem. In order to solve the above-mentioned problems, the present invention provides a vehicle generator operated by a motor or a generator, and a turbocharger provided with a turbocharger, which lacks a turbo action. A turbocharger rotating electric machine that is driven by a motor and is operated by a generator when the energy of the exhaust gas is large, and supplies the electric power generated from the vehicle generator or the turbocharger rotating electric machine to a battery and an electric load. And a control means for controlling the motor operation or the generator operation of the vehicle generator and the turbocharger rotating electric machine and for controlling the regulator, the control means comprising: Equipped with a counter that determines the frequency of braking for a predetermined time in the last The maximum output current of the regulator when
During normal driving without braking, the regulator is controlled so that the battery charging current is set to a value set according to the braking frequency level, and when the battery voltage is higher than the allowable charging voltage upper limit, the output current of the regulator is controlled. And when the battery voltage is smaller than the allowable lower limit of the charging voltage, the output current of the regulator is increased. [Operation] In an exhaust energy recovery apparatus provided with a turbocharger rotating electric machine in addition to a vehicle generator,
When the battery generated by the recovered energy is charged to the battery via the regulator, it cannot be charged any more once the battery is fully charged. Energy increases. Therefore, the regulator controls the amount of charge during normal running with no brake applied such that the greater the frequency of braking, the smaller the amount of charge. Then, at the time of braking, the battery is charged by making maximum use of the recoverable energy. Since the power generation by the vehicle generator during normal driving is performed by consuming fuel, the fuel consumption is improved by reducing the charging by the fuel. Also, the energy recovery efficiency during braking is improved. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of an exhaust energy recovery device of the present invention, and the reference numerals correspond to those in FIG. 16-1 is a counter, 17 and 18 are current sensors, and 19 is a brake switch. Current sensor 17
Detects the current (charge current, discharge current) of the battery 13, and the current sensor 18 detects the output current of the regulator 14. The counter 16-1 is provided in the control unit 16,
The switch signal from the brake switch 19 within a predetermined time (for example, 10 minutes) in the past from the current time is counted. That is, the number of brakes within a predetermined time in the latest past is recorded. The components having the same reference numerals as those in FIG. 5 are the same, and the description thereof will be omitted. In the present invention, the battery 13 is charged as much as possible with the energy that can be recovered during braking, so that the charge during normal driving is reduced.
However, even if the charge is reduced, it is necessary to avoid the battery from being in an overdischarged state. If the charge during normal driving is reduced, the amount of power generated by the vehicle generator 1 can be reduced, and the consumed fuel can be reduced. For this reason, charging during normal running is performed in consideration of the frequency of braking. The greater the frequency, the greater the chance of charging with the recovered energy during braking, and therefore the less the charging during normal driving. In addition,
The control of the battery charging current is performed by controlling the regulator 14. The relationship between the brake frequency and the battery charging current to be controlled is set in advance based on experiments and the like, and stored in the control unit 16. FIG. 2 is a diagram showing an example of the correspondence between the brake frequency level and the battery charging current. In this example, levels are classified according to the number of brakes in the last 10 minutes. For example, those brake count is 4-7 times, and the brake frequency level L _3. The number of levels to be divided and how many times to what level are determined as needed. Further, the battery charging current is set to I in accordance with the brake frequency levels L _{1 to} L _5.
Although set to ₁ ~I _5, this setting is also performed appropriately based on experiment or the like. FIG. 3 is a flowchart for explaining the control operation of the regulator when charging the battery. Block C in the flowchart is control for protecting the battery, block D is control during braking, and block E is control during normal running. Step 1: Detect the voltage of the battery 13 and determine the allowable upper limit of the charging voltage (the maximum charging voltage for preventing overcharging. For example,
27V) is checked. Step 2: If the charging voltage is larger than the allowable upper limit value, the output current of the regulator 14 is reduced. Step 3: The voltage of the battery 13 is detected, and it is checked whether the voltage is lower than an allowable lower limit value of the charging voltage (a minimum charging voltage for preventing an overdischarge state, for example, 21V). Step 4: If the charging voltage is smaller than the allowable lower limit, the output current of the regulator 14 is increased. Step 5: Check whether the brakes are applied now. This can be known from a signal from the brake switch 19. Step 6: During braking, control is performed so that the output current of the regulator 14 becomes maximum. This is because the energy that can be recovered during braking is charged to the maximum use. Step 7: The control after this step is as follows:
This is control when the brake is not applied, that is, during normal running. At the time of normal running, first, the count value of the counter 16-1 is checked to check the brake frequency (the number of brakes applied within a predetermined time). Step 8 ... brake frequency is examined whether or not corresponding to the frequency level L ₁ in FIG. [0030] Step 9: brake frequency level in the case of L _1, and controls the charging current to the battery 13 to I _1.
This control detects the charging current by the current sensor 17, it performs by controlling the regulator 14 so that I _1. Steps 10 to 17 In these steps, as in Steps 8 and 9, it is checked which brake frequency level corresponds to, and the regulator 14 is controlled so that the charging current is determined in accordance with the level. Control. When the "battery charge current" set in FIG. 2 is negative, it means the current discharged from the battery. When the braking frequency is high (for example, L ₅ ), the battery may be charged with the recovered energy at the time of braking, so that the battery may be discharged during normal driving (for example, I ₅ = −5 A is set). ). As described above, according to the exhaust energy recovery apparatus of the present invention, the regulator during normal driving without the brake is applied such that the greater the frequency of braking, the smaller the amount of charge. In braking, the battery is charged by making full use of the energy that can be recovered.This improves the energy recovery efficiency during braking, reduces the load on the vehicle generator during normal driving, and reduces fuel consumption. Be improved.

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 an example of a correspondence relationship between a brake frequency level and a battery charging current; FIG. 4 is a flowchart illustrating a control operation of a regulator at the time of operation. [FIG. 4] A diagram showing a configuration of an exhaust energy recovery device. [FIG. 5] A block diagram of a conventional exhaust energy recovery device. [FIG. 6] A diagram showing an example of a configuration of a regulator. FIG. 7 is a diagram showing a torque-up required area and an energy recovery area. [Description of References] 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 unit, 17, 18 current sensor, 19 brake switch, 20 pulley, 21 engine, 22 intake pipe, 23 exhaust pipe, 24 belt
25 ... pulley, 26 ... turbocharger, 27 ... compressor blade, 28 ... turbine blade, 29 ... electric load

Claims (1)

(57) [Claims] [Claim 1] A vehicle generator driven by a motor or a generator and a turbocharger provided with a turbocharger, the motor is driven when the turbo action is insufficient, and exhaust gas A turbocharger rotating electric machine that is driven by a generator when the energy is large; a regulator that performs control for supplying power generated from the vehicle generator or the turbocharger rotating electric machine to a battery and an electric load; In an exhaust energy recovery apparatus comprising a generator and control means for controlling the motor operation or the generator operation of the turbocharger rotating electric machine and for controlling the regulator, the control means controls the brake frequency for the latest past predetermined time. Equipped with the required counter, when the brake is applied, maximize the output current of the regulator, During normal running with no rake, the regulator is controlled so that the battery charge current is set to a value set according to the brake frequency level, and when the battery voltage is higher than the maximum allowable charge voltage, the output current of the regulator is controlled. And the output current of the regulator is increased when the battery voltage is smaller than the allowable lower limit of the charging voltage.