MISER in Detail
The MISER design is a mechanically, inﬁnitely variable dual path energy transfer system with a sophisticated microprocessor control system. MISER has fewer energy ﬂow paths, fewer valves and fewer parasitic losses (e.g. charge pumps) than existing hybrid systems. MISER is more advanced than electric systems, thanks to its more eﬃcient energy recovery, storage and delivery; it is inherently more eﬃcient than its competitors for at least two main reasons:
- At most times it is a dual path system where only a portion of the energy ﬂows through the hydraulic path and;
- Even in the hydraulic path, there is only one hydraulic unit and it is not a full hydrostatic drive.
The MISER transmission is a “compound” type hybrid drive meaning in some modes it is a “series” system (where the engine can charge the storage system with energy for later use) and in other modes it is a “parallel” system (where the energy is delivered from the engine, or the storage system, or a combination of both to the ﬁnal drive). This depends on which one of the 13 possible modes is selected by the control system; the operator of the vehicle will also be able to change options under certain conditions. This gives MISER the capability to optimize both fuel usage and performance of the vehicle better than existing technologies.
The MISER System can be summarized as a:
- fully automated;
- inﬁnitely variable;
- dual energy path;
- engine optimizing;
- regenerative braking transmission.
The MISER system installation can be done in two distinct ways. The ﬁrst can be described as “part MISER”, and involves the ﬁtment of the energy recovery components only -‐ this installation type is called the Hybrid Kinetic Energy Recovery System, or HKS for short. The second, or “full MISER” installation, involves the replacement of the vehicle’s original gearbox as well as the ﬁtment of energy recovery. This is called the Hybrid Transmission System, or HTS for short.
Research & Development
When run as a proof of technology, MISER has been proven to work in all modes. This was determined by a realistic model of an engine, hydraulic unit and accumulator that were developed; using this model, several simulations of various scenarios were completed. The model will also be used for generic vehicle studies. MISER engineers created a development vehicle by adapting a Toyota Hilux 2.0 D-4D. Although the vehicle was not optimized due to its use of “oﬀ the shelf” components, the results and performance were exceedingly good. The development vehicle was used as a test bench only and was driven intermittently over a period of nine months.
The MISER transmission in the development vehicle was tested as follows:
- Set up the transmission clutches and brakes for a speciﬁc test for the 13 modes.
- Prove each mode one at a time for that test.
The modes were tested as follows:
- Once a mode had been successfully demonstrated, the clutches and brakes settings were locked for the next mode; adjustments were made until that mode had been successfully tested.
- Once each mode was successfully demonstrated, the brakes and clutches for the next mode were locked, until all modes were shown to work.
While the overall MISER function was not optimized, the purpose of this process was to answer the question of whether the engineering theory behind the design was sound, which it proved to be.
This development phase will also determine the performance of a MISER‐equipped vehicle in relation to a conventional vehicle and will allow the prediction of a realistic savings percentage that the MISER can achieve. The two key output areas are:
- To calculate the theoretical regenerative braking a MISER can recover, including all ineﬃciencies. This data will then be used to determine optimum accumulator and pump sizes for future designs.
- To determine fuel savings as a result of the optimisation of the engine using MISER, relative to a conventional transmission.
Final development of the control system depends on further simulation results that are yet to be collated over the next nine months. However, the current simulation has shown that the basic hardware and interfaces to the gearbox control unit are operational (this includes a data logging function). What is still required is to mount the control system in the vehicle and then drive the vehicle in speed summing mode. Once that has been completed, each of the other modes will be developed based on the simulation work. The major undertaking in this area is to determine which mode to use at which time and how to transition between modes. It has been seen that this transition will require an advanced control system, the development of which will require signiﬁcant work and funding. The HKS will be completed ﬁrst; the HTS will follow.
The MISER universal drive/transmission is mechanically quite simple and comparatively small, which allows a single design to be ﬁtted to a wide range of passenger vehicles, negating the need to develop multiple versions of MISER for that market. The basic mechanical layout of a universal gearbox has been developed for use in vehicles up to the size of a Jeep or Land Rover. This concept must be conﬁrmed by detailed design and sizing using industry standards and commercial software. The design concept allows for the gearbox to be mounted virtually in any position (front, right, left, rear of the vehicle driving the front or rear axles, or both). The areas that still require some work are the hydraulic pump and the selection of the clutches and brakes. The basic design will be used to develop MISER transmissions for midrange truck‐type vehicles and another version for large trucks and earth movers.
What is now required is that the generic components used for the MISER system in the development vehicle need to be replaced by production versions. This process will require a timeframe of nine to twelve months, and will include the development of both HKS and HTS. Once this development is complete, full production implementation can be engaged with specialist transmission manufacturers.
MISER’s Key Capabilities
- CVT (inﬁnitely continuously variable transmission).
- Speed Summing: matching engine speed to the required road speed via its 13 modes.
- Torque summing: optimisation of engine fuel consumption.
- Longer gearing, with the additional optimisation modes and deployment of the stored kinetic energy from the regenerative braking.
- Regenerative braking.
- Hydraulic (not electric).
MISER’s Key Advantages
- More eﬃcient than competing systems due to only one pump/motor running, and no parasitic pump charging at any time.
- Mechanically simpler than competing systems, due to fewer working parts.
- Application includes a comprehensive vehicle range ‐ from smaller cars to the very largest earth moving vehicles.
- Applicable to all drive cycles.
- Fully automated.
- Limited change to current vehicle manufacturing infrastructure.
This schematic is an example of a typical MISER layout.
Below is a drawing showing the basic layout of an HKS installation in a large truck. This is purely for demonstration purposes and does not show the full implementation; rather, its purpose is to give the reader some idea of the main components that make up the HKS and how it would be installed in such a vehicle. For the HTS system, a retroﬁt MISER transmission would replace the current unit.
MISER is an enabling technology for existing vehicles with broad market applications. After driving the proof of technology in our development vehicle, we are very conﬁdent with our design and the results.
- The market needs our solution. The world has set itself emissions and eﬃciency goals and MISER can most eﬀectively address not only the automotive sector, but other applications where internal combustion engines are used. The implementation of MISER will add no cost to a new vehicle. Considering the savings to the vehicle owners and rebates oﬀered to manufacturers by governments, this most certainly has the potential to be a very eﬀective and proﬁtable solution.
- Retroﬁtting MISER to heavy trucks will cost no more than a replacement gearbox, and the ROI could be as little as four months.
- The MISER system is a very exciting project utilising technology that will signiﬁcantly beneﬁt the environment.