Abstract:
Engines produce not only primary energy in the form of kinetic energy transmitted through a rotating crankshaft but also secondary energy which may comprise kinetic energy in other forms as well as thermal energy. In order to reduce engine running costs and increase efficiency there is a desire to make best use of all forms of energy produced by an engine. The disclosure relates to the adoption of an equivalent consumption minimisation strategy by which the engine may be controlled to derive useful energy from a first proportion of primary energy and a second proportion of secondary energy wherein the first and second proportions are selected to minimise overall energy consumption.

Description:
TECHNICAL FIELD 
       [0001]    A control system for an engine assembly using equivalent consumption minimisation strategy. 
       BACKGROUND 
       [0002]    Internal combustion engines generally have efficiencies of well below 50%. Increasing energy efficiency is highly desirable for improving fuel economy, making better use of energy resources and meeting regulatory targets. Efforts to reduce fuel consumption by altering the engine and its control system to maximise the proportion of potential energy in the fuel which is converted into useful kinetic energy in the crankshaft are well known. 
         [0003]    While these techniques are, of course, beneficial for improving engine efficiency, it is necessarily the case that an engine produces secondary forms of energy (incidental to the kinetic energy of the crankshaft) which are often not usefully employed. 
         [0004]    Against this background, there is provided an engine assembly as disclosed herein. 
       SUMMARY OF THE DISCLOSURE 
       [0005]    The disclosure provides an engine assembly  1  comprising:
       an engine  20  configured to convert energy in a fuel  15  into primary output energy  25  and secondary output energy  35  wherein the primary output energy  25  consists solely of primary output kinetic energy in the form of a rotating crankshaft for onward transmission to a gearbox and/or a load  1000  and the secondary output energy  35  comprises secondary output kinetic energy and secondary output thermal energy;   a recovery device  40  configured to convert the secondary output energy  35  to potential energy  45 ;   a transducer  60  suitable either for converting the potential energy  45  to tertiary energy  65  for conversion by the engine  20  into primary output energy  25  or for converting the potential energy  45  directly to primary output energy  25 ; and   a controller  100  configured to implement an equivalent consumption minimization strategy in order to control overall consumption of fuel by continuously optimising a proportion of the primary output energy  25  derived from the energy in the fuel  15  and a proportion of the primary output energy  25  derived from the potential energy  45 .       
 
         [0010]    An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic diagram showing the features and embodiment of the engine assembly of the disclosure; 
           [0012]      FIG. 2  is a schematic diagram showing example inputs and outputs of the ECMS; 
           [0013]      FIG. 3  is a schematic diagram showing an implementation of the arrangement of the disclosure; 
           [0014]      FIG. 4  is a schematic diagram showing a more specific implementation of the arrangement of  FIG. 3 ; 
           [0015]      FIG. 5  is a schematic diagram of a specific implementation of the arrangement of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Referring to  FIG. 1 , there is illustrated an engine assembly  1  comprising an engine  20 , a recovery device  40 , a transducer  60  and a controller  100 . 
         [0017]    The engine  20  is configured to receive fuel  15  from a fuel tank  5  and to convert energy in the fuel into primary output energy  25  and secondary output energy  35 . The primary output energy  25  may take the form of kinetic energy in a rotating crankshaft. The rotating crankshaft may be connected to an engine load  1000 , perhaps via a gear box (which may or may not be considered to constitute a part of a load). 
         [0018]    The secondary output energy  35  may comprise secondary output kinetic energy and/or secondary output thermal energy. The secondary output energy  35  may be supplied to the recovery device  40 . The recovery device  40  may be configured to convert the secondary output energy  35  to potential energy  45 . Optionally, the engine assembly  1  comprises a potential energy storage feature  50 . Where the potential energy  45  is electrical potential energy, the potential energy storage feature  50  may be a battery. 
         [0019]    Potential energy  45 , either supplied directly from the recovery device  40  or from the potential energy storage feature  50  may be supplied to the transducer  60 . The transducer  60  is suitable for converting the potential energy  45  into tertiary energy  65  for conversion by the engine  20  into primary output energy  25  (and potentially also secondary output energy  35 ). 
         [0020]    The controller  100  is configured to implement an equivalent consumption minimisation strategy. This may be achieved using a data library which may be derived from offline engine modelling. Alternatively, equivalent consumption minimisation strategy may be achieved by online calculations in the engine controller. The controller  100  controls supply of fuel  15  from the fuel tank  5  to the engine  20  and supply of tertiary energy  65  from the transducer  60  to the engine  20 . In particular, it controls the ratio of energy to be derived in the engine  20  from fuel  15  to energy to be derived in the engine from tertiary energy  65 . 
         [0021]    The controller  100  comprises control lines  101 ,  102 ,  103 ,  104  and  105  for controlling the supply of fuel, the recovery device  40 , where present a battery, the transducer  60  and the engine  20 , respectively. The control lines may exercise control directly or indirectly. In respect of the control of the supply of fuel  15 , this may be achieved, for example, by controlling the demanded engine load on the crankshaft. 
         [0022]    EMCS is achieved by applying a search algorithm wherein the algorithm attempts to find a minimum fuel consumption for a given set of conditions. In an online system the data resulting in minimum predicted fuel consumption would be calculated in real time. In an offline system, a model of the system would attempt to predict the best possible outcome and output it to the data library for online retrieval by the controller  100 . It may be that expected drive cycles can be used to identify optimised values for the desired condition. This is particularly relevant when using an offline model. 
         [0023]    In simple terms, the input and output of the ECMS are shown in  FIG. 2 . The input represents the demands while the corresponding output indicates a predicted most efficient solution of X kW of energy to be derived from tertiary energy  65  and Y kW of energy to be derived from fuel  15 . 
         [0024]    In a more specific embodiment of the invention, the secondary output energy  35  may comprise secondary output kinetic energy. Specifically, the secondary output kinetic energy may comprise kinetic energy of an exhaust gas produced in the engine  20 . In this case, the recovery device  40  may comprise an electric generator for converting the secondary output kinetic energy of the gas into potential energy  45  which is electrical potential energy. Electrical potential energy may or may not be transmitted to a battery for storage. In this embodiment, the transducer  60  may comprise a motor. The motor may receive potential energy  45  either directly from the electric generator or from the battery. In this embodiment, it may be that the electric generator and the electric motor are a single electric machine. Furthermore, the electric generator and electric motor (whether or not a single machine) may be part of a turbo charger. 
         [0025]    The battery may comprise additional sources of electrical potential energy and additional drains of electrical potential energy beyond those explicitly described. That is to say, the battery may comprise inputs other than that from the recovery device  40  and outputs other than that from that to the transducer  60 . 
         [0026]    In an alternative embodiment, the recovery device  40  may comprise a thermo electric device for conversion of secondary output thermal energy. This second embodiment may or may not include a battery or other electrical potential energy storage device for storage or electrical potential energy derived in the electric device. 
         [0027]    Other alternative embodiments fall within the scope of the appended claims. In particular, any conceivable recovery of secondary output energy  35  by means of a recovery device  40  and redeployment of that energy using a transducer  60  to provide energy back to an engine  20  for more efficient use is contemplated. 
         [0028]    The arrangement of the disclosure recognises the significance of engines generally having significantly lower efficiencies than transmission systems to which the engine may be coupled. At the heart of the disclosure is therefore an attempt not simply to recover secondary energy which would not otherwise usefully be used, but to seek to recover that secondary energy as close to the source of that secondary energy as possible. In the case of an engine, it might, for example be the case that 70% of the energy produced constitutes secondary energy. Therefore, even if a small proportion of the 70% secondary energy can be recovered for useful use either immediately or a later time, this represents a significant energy efficiency advantage. Therefore the application of ECMS to an engine assembly may yield better efficiency improvements than when applied to a transmission system comprising an engine assembly. 
         [0029]    Furthermore, the use of an equivalent consumption minimisation strategy allows for predicting how best to achieve a particular desired output in terms of availability of primary energy directly from the fuel and availability of primary energy derived from recovery of secondary energy via the arrangement of the disclosure. Furthermore, the strategy allows for predictions about likely future engine desired behaviour to reduce overall fuel consumption for the same benefit over an extended period. 
         [0030]    The ECMS control techniques of the arrangement of the disclosure may be used in combination with other known control techniques including, but not limited to, fuzzy logic and feedback linearization. 
         [0031]    Control lines  102 ,  103 ,  104 ,  105  may not go directly from the controller  100  to their respective engine assembly features. Instead, one or more of these control lines may go via one or more other lower level controllers for more specialised onward processing, the result of which being sent to the respective engine assembly features. Such lower level controllers include, but are not limited to an MPC or EMPC controller. 
         [0032]    The detailed description of this disclosure has been made with respect to a small number of embodiments. The scope of the present disclosure is to be considered in light of the appended claims. It should not be inferred that one or more specific implementations of the desired description is intended to limit the scope of the claims beyond the scope of the claims themselves. 
       INDUSTRIAL APPLICABILITY 
       [0033]    The present disclosure provides an engine with a controller configured to implement an equivalent consumption minimization strategy in order to control overall consumption of fuel by continuously optimising a proportion of the primary output energy derived directly from the energy in the fuel and a proportion of the primary output energy derived indirectly from the energy in the fuel. 
         [0034]    Advantageously, this may allow for overall increased engine efficiency.