JPS60216703A - Brake system of internal-combustion engine driven electric vehicle - Google Patents

Abstract

PURPOSE:To improve fuel consumption by reducing fuel supply amount to an internal-combustion engine when the rotating speed of the engine becomes an idling speed or higher at the brake operating time by an engine brake. CONSTITUTION:The output of a synchronous generator 2 which is coupled with a Diesel engine 1 is supplied through a generator side converter 3 and motor side converters 5L, 5R to wheel driving induction motors 6L, 6R. The engine 1 becomes an idling state at the brake operating time, brake powers generared from the motors 6L, 6R are supplied through the converters 5L, 5R and the converter 3 to a synchronous generator 2, and an engine brake is operated. At this time, when the rotating speed of the engine 1 becomes the idling speed or higher, a fuel supply amount reduction command is applied to a fuel supply unit 23 through a system controller 31.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a braking system for an internal combustion engine-driven electric vehicle that runs on electric power from a generator driven by an internal combustion engine.

[Prior art and its problems]

Large vehicles such as large dump trucks and self-propelled crane trucks
For construction equipment vehicles, etc., the equipment mounted on the vehicle can be made smaller and lighter, and maintenance is easier. For this purpose, the internal combustion engine is used to drive the generator, rather than the conventional mechanical system that applies power from the internal combustion engine to the wheels via a clutch, reduction gear, or differential gear. Overnight, electric systems began to be used, with the output of a generator driving a traction motor connected to the wheels. With the development of semiconductor power converters in recent years, electric power converters are now preferred over DC power converters, which have good controllability but are difficult to maintain and cost.

FIG. 1 is a main circuit connection diagram showing a conventional example of an internal combustion engine-driven electric vehicle driven by an induction motor.

In FIG. 1, a synchronous generator 2 is coupled to a laser engine l as an internal combustion engine, and the AC power output from the synchronous generator 2 is converted to DC power by a generator-side converter 3 made of a thyristor. It is converted and fed to the DC intermediate circuit. This DC intermediate circuit has a filter reactor of 4L.
An inverted filter formed by a filter reactor 4C and a filter reactor 4C is provided to remove the pulsation component contained in the single DC power from the generator side converter 3. The DC power smoothed by this filter is input to motor side converters 5L and 5R, which are composed of gate turn-off thyristors. The induction motor 6L that drives the left wheel receives AC power from the left wheel motor side converter 5L, and the induction motor 6R that drives the right wheel receives AC power from the right wheel converter station. Motor side converters 5L and 5R
Since the aforementioned smoothed DC power is separately converted into a variable voltage/variable frequency cross (N, 'flL force), the rotational speed and torque of the induction motors 5L and 5R, that is, the running speed and traction torque of the vehicle, are determined by the electric motor. It is controlled by the conversion operations of the side converters 5L and 5R.Also, as mentioned above, the right and left wheels are controlled separately, so this vehicle can run smoothly on curves, and the distance between the wheels and the ground is controlled separately. Even if slippage occurs, this slippage can be quickly eliminated by controlling the torque and rotational speed of the wheel.

When a running vehicle configured as described above enters a braking operation, the diesel engine 1 is likely to be in an idling state, so the synchronous generator 2 generates an alternating current voltage, which is transferred to the converter on the scatterer generator side. 3 and motor side converter sL,
A so-called DC intermediate circuit between the generator and the generator 5R is also photoelectrically powered by the DC voltage from the generator side converter 3. Assuming that the vehicle is going down a slope, the left and right induction motors 6L and 6R are rotated through the wheels by the potential energy possessed by the vehicle, so these induction motors 6L and 6R become induction generators and generate AC power. occurs, and the motor side converter 5L, 5
R converts this AC power into DC power and sends it to the DC intermediate circuit. At this time, since the synchronous generator 2 is generating an alternating current voltage as described above, the generator side converter 3 can perform reverse conversion operation in the same way as a separately excited converter connected to a normal power system. Therefore, by performing a reverse conversion operation on the generator side converter 3, the power sent from the induction motors 6L and 6R to the DC intermediate circuit is converted into AC power and sent to the synchronous generator 2.

The synchronous generator 2 receives this AC power and becomes a synchronous generator, and its speed is lower than the speed of the diesel engine 1 during idling. This increase in the speed of the diesel engine 1 during idling means that engine braking is applied, so the energy held by the vehicle that is exiting the vehicle is eventually absorbed by this engine braking, and the traveling speed of this vehicle is reduced. It will be suppressed. Furthermore, since a braking resistor 8 is connected to the synchronous generator 2 via a SIRIS rectifier 7, this SYRISC rectifier 7 is operated and the alternating current power reversely converted by the converter 3 on the machine side is transferred to the braking resistor. It is also possible to suppress the running speed of this vehicle by making it consume 8. That scattered generator side converter 3
The braking power generated by the induction motors 6L and 6R is transferred to the diesel engine 1 by appropriately controlling the thyristor rectifier and thyristor rectifier 7.
It is distributed to the braking resistance 8 and consumed to suppress the running speed of the vehicle.

However, in the above-described system, the diesel engine 1 is idling during braking, so fuel is constantly supplied for this purpose.

Therefore, this diesel engine 1 does not fully utilize its engine braking performance, so the distribution of braking power consumed by the braking resistor 8 increases, so the braking resistor 8 and the sirisk rectifier 7 are made smaller and lighter. Not only is the payload and space available for the intended purpose of the vehicle obstructed, but also the braking resistance 8 t
This has the disadvantage that the fuel consumption of the vehicle deteriorates.

FIG. 2 is a main circuit connection diagram showing a conventional example of an internal combustion, single-displacement drive, pneumatic vehicle that runs on direct current power.

In FIG. 2, AC power from a synchronous light machine 2 driven by a diesel engine 1 is converted to DC power by an armature converter 11L made of Cyrisk to drive the left wheel, and the braking resistance 12L is applied to the armature 13L of the DC current #1 machine with one diameter, but when driving in full force, the braking resistor 12L is short-circuited with the short-circuit switch 14L,
fence. In order to drive the right wheel, an armature converter 11R, a braking resistor 12R, a braking resistor 13R, and a short circuit switch 14R having the same functions as those for the left wheel are provided. The DC force from the field converter 11F, which is caused by the The polarity of the windings 15L and 15R can be changed by a field changeover switch 16.

When the vehicle is driven in the forward direction, the short circuit switch 14
Turn on L and 14R, short-circuit braking resistors 12L and 12R, and connect armature converters 11L and 11R to field converter 11.
F is operated in forward conversion operation, and the left and right electric motors are operated at the desired speed and torque. During braking operation, the wheels, that is, the electric four wheels, are rotated in the same direction as during forward driving, so operate the field changeover switch 16 to change the field windings 15L and 15R.
When the direction of the current flowing in is reversed, the wake-up machine 13L,
A voltage opposite to that during forward driving is generated at 13R. Therefore, by idling the diesel engine 1 and generating father-flow kick pressure from the synchronous generator 2, the armature converter]
, IL, and IIR are operated, the DC power from the generator and γX is converted to father current power, and the same AA @' machine 2 is operated as a motor. The diesel engine 1 is rotated at a higher speed than when idling, and engine braking is applied. At this time, if the short-circuit switches 14L and 14R are turned off, braking power is consumed by the braking resistors 12L and 12R.

The ratio of braking power borne by the braking resistors 12L, 12R and the engine brake is the armature converter 11L, IIR.
It can be adjusted by adjusting the output voltage.

However, even with the conventional system shown in FIG. 2, fuel is supplied to the diesel engine 1 for idling, so the engine 1 cannot fully utilize its engine braking performance, and the braking resistances 12L and 12R are As already mentioned, the braking resistors 12L and 12R cannot be made small and light because braking power must be consumed, which causes various inconveniences.

[Purpose of the invention]

This invention utilizes 100% of the engine braking performance possessed by the internal combustion engine during braking operation, thereby making it possible to minimize the size of other braking means such as braking resistance, thereby improving fuel efficiency. The purpose is to provide a braking method.

[Key points of the invention]

This invention provides a method of reducing or eliminating the amount of fuel supplied to the internal combustion engine when the internal combustion engine rotational speed is equal to or higher than a first speed setting value, which is approximately the idling operating speed, when performing braking operation using the engine brake. The purpose is to generate an extra braking force corresponding to the energy reduced by this fuel reduction. Furthermore, by using braking energy to increase the speed of the internal combustion engine to a second speed setting value that is the maximum allowable speed, the braking energy absorbed by the internal combustion engine is increased.

[Embodiments of the invention]

An embodiment of the present invention will be described below in which a diesel engine is used as an example of an internal combustion engine.

FIG. 3 is a graph showing the amount of fuel supplied when the engine brake is activated according to the present invention, in which the horizontal axis represents the rotational speed of the engine, and the vertical axis represents the amount of fuel supplied to the engine. In Fig. 3, when engine braking is applied to the diesel engine, if the speed of the diesel engine exceeds the first speed setting value N1, that is, the idling speed, the amount of fuel supplied to the engine is reduced. Eventually, the fuel supply amount will be reduced to zero.

By reducing the amount of fuel in this manner, braking energy commensurate with the amount of reduction can be absorbed as extra engine braking, resulting in improved engine braking performance compared to conventional methods.

Figure 4 shows the speed when the engine brake is applied according to the present invention.
This is a graph showing braking torque characteristics, with the horizontal axis representing engine rotational speed and the vertical axis representing braking torque. In this Figure 4, at speeds lower than the idling speed N1, the effect of engine braking is slight;
Other braking methods, such as consuming braking energy in braking resistance or applying mechanical braking, do not use engine braking. Engine braking is applied from an idling speed of N1, and as the fuel supply amount is reduced as shown in FIG. 3, the braking torque increases, and when the fuel is zero, the braking torque reaches the maximum value TQ.

If the braking energy further increases in this state, the engine's speed will increase due to the braking torque TQ, and the engine will absorb the increased braking energy. Once the engine speed reaches the allowable high speed of N2, it is dangerous for the engine to absorb any more braking energy, so the excess braking energy is consumed by braking resistance or mechanical braking. do.

FIG. 5 is a circuit diagram showing an embodiment of the present invention, and this circuit performs the esogen brake operation as shown in FIGS. 3 and 4.

In FIG. 5, a synchronous generator 2 is coupled to a diesel engine 1 as an internal combustion engine to generate alternating current power,
The generator-side converter 3 converts this AC power into DC power. The pulsation of this DC power is removed by a filter reactor 4L and a filter capacitor 4c, and the AC power converted by the motor side converter 5L is applied to the induction motor 6L for the left wheel. ,
Similarly, since AC power converted by the motor-side converter 5R is applied, the vehicle can obtain the desired running speed and traction torque, as in the conventional example.

During braking operation, the braking power output from the induction motors on the left and right sides of the kidney is converted into DC power by converters 5L and 5R on the motor side, and further converted into AC power by the converter 3 on the generator side, and this AC power is used for synchronous generation. The speed of the vehicle is suppressed by consuming the above-mentioned braking power by operating the electric motor of the lt machine 2 or by causing power loss to occur in the braking resistor 10 via the thyristor regulator 9.

A speed detector is coupled to the diesel engine 1,
Its speed can be detected at all times, and the fixed fuel supply number controls the amount of fuel supplied to the diesel engine 1 to adjust its output. The synchronous generator 2 is also equipped with an excitation device 21, which controls the excitation current supplied to the generator field winding η connected to the excitation device 21. Reference numeral 30 denotes a driving command device for the vehicle, which is composed of an accelerator pedal, a brake pedal, and the like. Furthermore, 31 is a system control device, which controls the fuel supply system of the diesel engine 1, the excitation device 21 of the synchronous generator 2, the generator-side converter 3, and the si-risk regulator based on commands from the operation controller I. 9. Control motor side converters 5L and 5R.

When the vehicle switches from forward driving to braking driving, the accelerator pedal is in a free state, but the driving command unit 30 issues this command, and the diesel engine 1 is placed in an idle link driving state. When the brake pedal is subsequently depressed, the braking power generated from the sieve 4 electric motors 6L and -6R is transmitted through the motor side converters 5L and 5R and the generator side converter 3 according to commands from the operation command device 30 and the system control device 31. Since the synchronous generator 2 is driven, the (b) rotational speed of the diesel engine 1 becomes higher than the idling speed and engine braking is applied. The speed detector detects this idling speed N1, and issues a fuel supply reduction command to the fuel supply device via the system control device 31 to increase the engine braking energy absorbed by the engine 1.

Even if the amount of fuel supplied to the engine 1 is reduced, when the generated braking power cannot be absorbed by the engine 1, the engine 1 increases its speed to the maximum allowable speed N2 and increases the energy absorption capacity of the engine. Speed is from N1 to N
2, all the generated braking power can be absorbed as engine braking, so there is no need to use the braking resistor 10.

If the speed of the engine 1 exceeds the maximum allowable speed N2, the engine 1 may be damaged, so the amount that cannot be absorbed by the engine brake at this time is applied to the mechanical brake or the braking resistance 10.
limit the energy that the engine 1 can absorb. Also, when the generated braking power is small and the speed of the engine 1 is less than the idling speed N1,
The system control device 31 executes these operations such that energy is consumed by the mechanical brake or the braking resistor 10 without applying the engine brake.

〔Effect of the invention〕

According to the present invention, when an internal combustion engine-driven electric vehicle is braked by engine braking, if the speed of the internal combustion engine becomes higher than the idling speed, the amount of fuel supplied to the internal combustion engine is reduced or eliminated. In addition, by increasing the speed of the internal combustion engine to a large permissible speed, even more braking energy can be absorbed. In other words, when the internal combustion engine speed is between the idling speed and the maximum permissible speed when the engine brake is applied, all the braking power generated from the traveling electric motor can be absorbed by the internal combustion engine.
Only a small amount of energy is consumed in braking resistance. Since the size and weight of the unfolding dynamic resistance can be reduced, not only the payload weight and space, which are the original purpose of the vehicle, can be increased, but also the braking resistance can be reduced, which improves fuel efficiency when traveling. Furthermore, since the amount of fuel supplied to the internal combustion engine is reduced or eliminated when the engine brake is activated, fuel efficiency can be improved here as well.

[Brief explanation of the drawing]

FIG. 211 is a main circuit connection diagram showing a conventional example of an internal combustion engine driven electric vehicle using an induction motor, and FIG. 2 is a main circuit connection diagram showing a conventional example of an internal combustion engine driven electric vehicle using a DC motor. FIG. 3 is a fuel supply amount graph when the engine brake is activated according to the present invention, and FIG. 4 is a graph of speed vs. braking torque when the engine brake is activated according to the present invention.
FIG. 5 is a circuit diagram showing an embodiment of the present invention. 1... Diesel engine as an internal combustion engine, 2...
・Synchronous generator, 3... Generator side converter, 4C... Filter capacitor, 4L... Filter reactor, 5
L, 5R...Motor side converter, 6L t 6R...
Induction motor, 7... Cyrisk rectifier, 8, 10...
・Braking resistance, 9... Thyristor regulator, IIF...
Field converter, IIL, IIR... Armature converter,
12L, 12R...braking resistance, 13L, 13R...
DC motor armature, 14L, 14R... Short circuit switch, 15L, 15R... DC motor field winding, 16...
・Field switching switch, acceleration/speed detector, 21...
Excitation device, n... Generator field winding,... Fuel supply device, Blade... Operation command device, Fig. 2 Ichina Engine speed ash Fig. 3 --> Engine speed - Fig. 4

Claims (1)

[Scope of Claims] 1) Electric power generated by a generator driven by an internal combustion engine mounted on a vehicle is applied to a traveling electric motor coupled to wheels to drive the vehicle at a desired speed, and also to brake the vehicle. In an internal combustion engine-driven electric vehicle, the internal combustion engine-driven electric vehicle is configured to apply braking energy generated by the traveling electric motor to the generator to operate the electric motor, thereby causing the internal combustion engine to absorb the braking energy and suppressing the speed of the vehicle. , when the speed of the internal combustion engine is below the first speed setting value during braking operation, the II energy to be absorbed by the internal combustion engine is reduced or zero; - when the speed of the internal combustion engine exceeds the first speed setting value; Reduce or eliminate the fuel supplied to the internal combustion engine, and when the speed of the internal combustion engine exceeds a second speed set value that is higher than the first speed set value, reduce or reduce the braking energy absorbed by the internal combustion engine. A braking system for internal combustion engine-powered electric vehicles that aims to reduce the temperature to zero. 2. In the braking system described in claim 1-,
- A braking method for an internal combustion engine-driven electric vehicle, characterized in that the first speed setting value of the internal combustion engine is set approximately equal to the idling operating speed of the internal combustion engine. 3) In the braking method according to claim 1, the second speed setting value for the internal combustion engine is set smaller than the maximum speed allowable for the internal combustion engine. Braking method.