SE468133B - SETTING AND DEVICE FOR CONTROL OF AN ENERGY CONVERSION SYSTEM - Google Patents

Description

lO 15 20 25 30 35 468 155 2 can be divided into fuel / air regulations and torque control systems. The former achieves by a change in the amount of combustible fuel / air mixture, corresponding change in the temperature of the heater wall well known to those skilled in the art, a change in speed and thus a change in the power emitted from the engine. The torque control systems aim at a change in the torque emanating from the engine at one and the same speed through a change in the working pressure of the working gas enclosed in the engine. This can be done in a variety of different and in more or less complicated ways.

In the event of a need for slowly varying torques, simple and safe systems have been designed that fully satisfy the control requirements, for example for marine engines. When there is a need for rapidly variable elements, different types of systems have been tried. The so-called average gas pressure system, where the amount of working gas in the cycle and thus the average gas pressure is regulated in step with the requirement for varying torques, provides fully acceptable speed, but is complicated to perform and therefore expensive to manufacture and is also associated with unwanted energy losses in the part of the control phase, which is associated with a rapid reduction of the torque. Such an expensive power control system has therefore greatly reduced the competitiveness of hot gas engines, for example when used in vehicles. A power control system that can satisfy the need for rapid torque change, which is also based on a change in mean gas pressure, is so-called step control. By enabling a change in the volume of the working gas in one or more steps, the engine's deliverable torque can be increased or decreased at each speed. This is a fairly inexpensive way of achieving power control. Due to the fact that this regulation takes place in steps, while in vehicle applications, for example, it is desired that the regulation takes place continuously, hot gas engines regulated in this way cannot be used.

Another problem in this context, which so far has not been solved, is that hot gas engines, in order not to wear extremely, require one to two minutes of heating time before they should be loaded. Thus, there is also an accessibility problem, since a user of an engine of this kind, for example in a car, requires immediate availability, just as with a petrol or diesel engine, which also means that hot gas engines cannot be used.

The main object of the present invention is to provide a control method of the kind mentioned in the introduction, which allows continuous variation of the power emanating from the energy conversion system.

Another object of the invention is to provide an energy conversion system whose availability is at least as good as that of a Diesel or Otto engine. The objects are achieved with a control method according to the invention which is characterized in that the power of the hot gas engine to the energy conversion system is increased or decreased in a couple or a few predetermined control steps at the same time as the power through an energy storage system included in each operating cycle. the conversion system is decelerated or raised to the desired level. The objects are further achieved with a device according to the invention, which is characterized by an energy accumulator for receiving power from the hot gas engine and a control system with which the output power of the energy conversion system is modulated in relation to a desired output power either by accumulating excess power in the accumulator or by withdrawal of power from the accumulator. Further purpose fulfillment is obtained by using more than one hot gas engine module in the energy conversion system.

An advantage of the invention is that the energy storage in the conversion system allows for a limited time operation of the system completely without exhaust emissions, eg driving a bus driven by the system in a garage.

Another advantage is that the maximum power of the energy conversion system is obtained by adding the maximum power of the hot gas engine and the maximum extractable power from the energy storage system. In this way, the maximum power of the hot gas engine (s) can be limited in relation to a conventional drive source, eg a Diesel engine.

A further advantage of the invention is that conditions are created for the construction of small city vehicles, which when driven in a city center can be driven electrically or by pressure fluid and outside the city center can be driven by a hot gas engine while the energy storage system accumulates the part of the engine ate to drive the vehicle.

Further advantages of the invention will become apparent from the following detailed description of preferred embodiments when considered in conjunction with the accompanying figures, in which: Fig. 1 schematically shows an application example of a city bus.

Fig. 2 schematically shows an application example of a light urban vehicle.

Fig. 3 schematically shows an application example of an urban distribution vehicle.

Fig. 4 shows the power output of the energy conversion system as a function of time for an imaginary driving cycle.

Fig. 5 shows, analogously to Fig. 4, the power emitted from the system as a function: åV? Ïïden for an imaginary driving cycle in another control mode.

Fig. 6 shows an application of the invention to a smaller reserve power unit.

Fig. 7 shows another example of the application of the invention to a smaller reserve power plant.

Fig. 1 shows a first exemplary embodiment of the use of the method according to the invention in hot gas engines in energy conversion systems and refers to the application in heavy or medium-heavy vehicles, for example buses or lorries in urban and suburban traffic. The drive source consists of two step-controlled hot gas engine modules 1 and 2, each with a burner 3 and a separate fuel / air control system 4, including fuel lines 5, fuel valves 6, air supply device 7 and combustion air fan 8.

The motor modules 1 and 2 in Fig. 1 are power-regulated in the example in three predetermined shaft torque steps, namely: - Full shaft torque, whereby at each speed the maximum output power is taken out of the respective motor module.

The engine speed is determined by the power requirement and can be affected by the amount of fuel or air supplied as well as by external and internal load via gearboxes (FL = distribution gearbox, VL = conventional gearbox).

- Half shaft torque, whereby at each engine speed approximately half the maximum shaft torque can be released. The engine speed is also determined here by the power requirement and can be affected in the same way as in the previous section.

- Idle shaft torque, whereby only so much shaft torque is generated that it corresponds to the power requirement for the vehicle drive system's auxiliary devices with the addition of a small energy charging requirement. This step constitutes a standby mode for the engine modules in anticipation of an expected rapid axle power requirement.

To the power control option with different shaft torque steps in each motor module comes the possibility to connect one, two or no motor module at all. The connection of the respective motor modules takes place, in particular, the shaft connections KI and KII. The above-mentioned * transmission gearbox FL engages either a gearbox VL for vehicle propulsion or a fluid unit, preferably a hydraulic unit HM / P, which in its pump position converts mechanical shaft power into accumulated hydraulic energy. The energy that accumulates comes either from one or both engine modules or from the vehicle's propeller shaft, in the latter case in the form of braking energy. The hydraulic unit HM / P, also has an engine position. The shaft torque from the HM / P unit can either drive the vehicle completely without any other addition of shaft torque, whereby exhaust-free operation of the vehicle is obtained, or with the addition of shaft torque from one or both engine modules 1 and 2 respectively. 468 135 10 15 20 25 30 35 6 On The distribution gearbox FL also houses the above-mentioned, conventional gearbox VL, which in a vehicle manner normally transforms speed and axle torque in a manner determined by the driving conditions of the vehicle. The gearbox is equipped with a clutch KIII for engaging and disengaging the PTO shaft 9 and thus the vehicle's drive wheels.

The hydraulic energy is stored in a pressure accumulator comprising a high-pressure part 10 and a low-pressure part 11, each of which is provided with a pressure bottle for nitrogen gas or some other suitable gas. The difference in hydraulic pressure between the high-pressure part l0 and the low-pressure part ll is a measure of the usable, accumulated amount of energy.

The described drive system with its step-controlled hot gas engine modules 1 and 2 provides a quickly adjustable shaft torque for the vehicle's drive, as energy is always available in accumulated form and the energy supply is always kept charged using the hot gas engine modules 1 and 2. The drive system is therefore adaptable to different driving cycles. and is controlled by a pre-programmed electronic control system (not shown in Fig. 1), all while the driver drives his vehicle completely conventionally with the accelerator pedal, brake pedal and possibly the clutch pedal and gear lever.

From an energy management point of view, it is important that as much of the required propulsion energy as possible is supplied to the drive wheels directly from the engine modules in order to avoid conversion losses and that as much of the vehicle's braking energy is stored in the accumulators. This is realized with the help of the electronic control system.

Fig. 2 shows in a manner corresponding to Fig. 1 an energy conversion system which in this embodiment has electrical energy storage. The energy conversion system is here adapted for driving a light urban vehicle. Due to a smaller power requirement, only one motor module 1 is used as the drive source 10 15 20 25 30 35 468 133 7, which, as before, is regulated in a few steps, eg three as in the previous example. The motor drives via a clutch KI 'a combined electric motor (electric generator set 12, which drives via a gearbox VL or via braking is driven by a PTO shaft 9, which is connected to the gearbox, which in turn drives a differential 13 and drive wheels 14 in a conventional manner. The electric unit 12 is controlled so that it provides different axle torques for the vehicle's propulsion in different driving cycles and so that when the vehicle is braked it stores braking energy in electric batteries.The electric unit is also used to store the hot gas engine's emitted power in the electric batteries in the form of electric energy. ie charge the electric batteries, or conversely to convert the electrical energy in the electric batteries to axle power for the vehicle's propulsion (see Figs. 4 and 5) .The control of energy management also takes place in this case by the previously mentioned, electronic control system, while the driver drives the vehicle in a conventional way with accelerator pedal and brake pedal as well as any clutch pedal and gear lever.In this case, too, it is essential that such a large As much as possible, the drive energy is transferred directly from the hot gas engine to the vehicle's drive wheel, while the energy delivered to or removed from the electric batteries is used to modulate the hot gas engine's output power, for completely exhaust-free operation, when desired or necessary, and to generate maximum shaft torque, eg at high acceleration, for temporary maximum speed, for reversing and combinations of these operating conditions.

In the examples shown so far, the application of the invention has been shown on drive systems with direct mechanical drive contact between the engine module or modules and the vehicle's drive wheels, the motive for such direct contact being the most efficient possible energy management.

In some applications, however, there may be reasons to refrain from direct mechanical coupling between the drive source, the hot gas engine, and the vehicle's drive wheels, for example cost, installation or flexibility reasons. Fig. 3 shows such an example in the form of a drive system for urban distribution vehicles.

In the figure, l 'is a hot gas engine which, as before, is regulated in steps. The engine is connected to a hydraulic pump 15 with variable stroke. The hot gas engine 1 charges by means of the pump a hydraulic accumulator having a low-pressure part 11 and a high-pressure part 10. The drive of the vehicle wheels 14 is effected by means of a combined motor and pump unit HM / P of hydraulic type via a gearbox VL, which may, for example, be of the continuously variable transmission (CVT) type. The vehicle's braking energy is utilized by the hydraulic unit HM / P acting as a pump and storing recoverable braking energy in the hydraulic accumulator in the form of hydraulic energy. Monitoring and control of the system is achieved automatically by means of an electronic, pre-programmed control system E. The driver of the vehicle drives in the normal way with the accelerator pedal, brake pedal and gear lever.

Figures 4 and 5 show how during hypothetical driving cycles the step-regulated shaft power from the energy conversion system is modulated as a function of time by adding or absorbing energy from each to an energy accumulator, which means that the hot gas engine shaft torque is regulated step by step, but in interaction with an energy accumulator, the result according to the invention is a completely continuous output power.

Fig. 4 shows in particular how this is achieved at the same time as the energy accumulator, which in this example is an electric accumulator, although exactly the same relationship applies to hydraulic accumulators or other types of energy accumulation, successively charged by supplying excess power via a generator operating as a generator. . The driving cycle shown shows how during time period A (hot gas engine switched off to obtain exhaust-free operation) the vehicle in operating mode I uno 10 15 20 25 30 35 468 153-9 is completely driven by the electric motor with energy from the electric accumulator. In the subsequent time period C, the engine has been started and delivers an output which is always greater than or equal to that required for the operation of the vehicle. The excess power is stored as electrical energy in the electricity accumulator. Next in the following period D means that full power is taken out of the hot gas engine, whereby excess power is stored in the accumulator. Only in cases where the vehicle's driving cycle requires greater power than the maximum throttle of the hot gas engine (during period D '), does the power supply as engine add extra shaft power. During time period B, the hot gas engine finally idles and delivers power only for driving auxiliary devices and possibly for maintenance charging of the accumulator.

Fig. 5 shows how the shaft torque of the energy conversion system is modulated and how the resulting shaft power resulting from the invention is completely continuous due to cooperation with an energy accumulator, in this case electric batteries. In the first part B of the driving cycle, you can see how the hot gas engine works at idle. With a relatively small power requirement, which is needed for the vehicle to start up, energy is supplied from the electric batteries and the electrical unit works alone as a drive motor. In the event of greater power requirements, the output power of the hot gas engine is gradually increased (power positions C-D-C) at the same time as the modulation of the power takes place through additional power from the electric drive motor. This mode of operation is used when the electric batteries are relatively fully charged.

At the end of the driving cycle, the hot gas engine can be completely switched off and the remaining part of the driving cycle can be completed by adding power from the electric drive motor. This corresponds to the hot power engine's shaft power position A, ie switched off hot gas engine and completely exhaust-free operation.

This type of vehicle operation is specially adapted for driving in confined spaces, such as garages or in traffic jams. The vehicle's operating modes and the hot gas engine's shaft power modes are as follows. 468 153 10 15 20 25 30 35 10 Operating mode l: Hot gas engine switched off Exhaust-free operation by hydraulic or electric motor Operating mode 2: Hot gas engine in operation Operation with constant shaft torque deficit Operating mode 3: Hot gas engine in operation (idle, 50%, 100%) excess or deficit in shaft torque Hot power engine shaft power positions: Time period A: The hot gas engine switched off Time period B: The hot gas engine in idle mode Time period C: The hot gas engine delivers approx. 50% shaft torque Time period D: The hot gas engine delivers full shaft torque.

The driving cycles shown in Figures 4 and 5 can of course, depending on the state of charge of the accumulators, be combined with the use of the previously mentioned control system E. From these figures it is also clear that the purpose relating to the system's availability in time is fulfilled.

Fig. 6 shows an example of utilization of the invention in electricity generation and in a reserve power plant.

Step-controlled hot gas engine modules 1 and 2 with burner 3 and connections KI and KII. The FL gearbox engages either one or both engine modules.

In a combined electric motor and electric generator M / G, the power supplied in steps is modulated from the hot gas engine modules in the same way as in the previously described application in vehicle operation, ie according to a certain driving mode all surplus energy is delivered to an electric accumulator A and according to a certain other driving mode. with additional power to modulate the stepwise supplied power from the hot gas engines. An electric generator G is operated via a connection KIII G. The energy conversion system's good responsiveness and safe and fast start make such a system ideal for use as a reserve power plant, for example in hospitals. Fig. 7 shows a hydraulic accumulation variant of the power plants and reserve power plants described above. Even in this case, fast responsiveness as well as safe and fast start can be guaranteed.

The hot gas engine systems controlled in this way by step and modulus can of course be used in a similar manner in combination with energy storage in other contexts, where the described properties are important.

Claims (4)

468 133 10 15 20 25 30 35 12 PATENT REQUIREMENTS 1. A method for continuously regulating the output power of an energy conversion system, which has at least one hot gas engine that can be regulated in power stages, characterized by - that an energy storage system with an accumulator and a generator / motor unit stores excess energy obtained when the hot gas engine exceeds power the need for output power from the energy conversion system, - that the energy storage system delivers power when the power emitted by the hot gas engine falls below the said need for output power, - and that the energy storage system's storage or output is controlled in such a way that the output power adjustable. Energy conversion system with at least one step-by-step controllable hot gas engine, characterized by - an energy storage system with an accumulator and a generator / engine unit for storage of excess energy obtained when the power delivered by the hot gas engine exceeds the need for output power from the energy conversion system; when the power delivered by the hot gas engine is below said need for output power, - and a control system, with which the storage or delivery of power of the energy storage system is controlled in such a way that the output power from the energy conversion system becomes continuously controllable over time. 3. An energy conversion system as claimed in Claim 2, characterized by a control gearbox controlled by the control system with an input shaft for each hot gas engine, a shaft for the accumulator, which shaft absorbs or emits power from the respective to the accumulators, and a .from system output shaft. 10 15 20 25 30 35 468 153 13 Energy conversion system according to claim 3, characterized in that the accumulator is of hydraulic or electrical type.