Compact cooling and safe coupling – KTR components in the new engine series H by Hatz
Hatz, the Lower Bavarian manufacturer of diesel engines, optionally supplies all types of the new engine series H as an open power unit ready to install. For cooling charge air and engine coolant, a combined cooler by KTR is used which was dimensioned in cooperation with Hatz. In addition, a compact engine oil cooler is part of the scope of delivery. If the engine is used on a hydraulic drive, a flange coupling of company KTR provides for the reliable connection with the pump.
Plug & Play: This is a vital feature with industrial engines mainly used by low volume manufacturers. Large manufacturers of construction and agricultural machines or forklift trucks, as an example, purchase the engine only and configure the peripheral equipment required such as cooling units, tubing and flange coupling by themselves. The manufacturers of special-purpose machines and vehicles in turn prefer so-called „power packs“ or „open power units“ which are ready to install as far as possible with the user being sure that engine and cooling systems have been perfectly matched.
New series H as an open power unit
Hatz provides all types of the recently developed series H as an open power unit (OPU) ready to install to this large clientele. The basic type, the water-cooled 4 cylinder Hatz 4H50TIC with 2 litres cylinder capacity and a maximum power of 55 kW makes use of common rail technology, turbo loaders and external exhaust gas recirculation. Series H meets the very strict emission regulations level III B (EU) and EPA Tier 4 final (USA) without using particle filters and has been designed based on a pioneering downsizing principle making the engine the most compact and most light-weight one of its class, as stated by the manufacturer.
Wide application range – high demands on cooling
As an OPU version the engines of series H are provided with all components required for cooling by the manufacturer. The user merely has to connect tank, primary filter and feed pump as well as battery and control. With the development Hatz paid special attention to developing a wide application range for OPU. The focus is mainly on machines like lifting platforms, hydraulic power packs, forestry machines and drilling equipment as well as stationary applications like pumps and generators.
Common projects
The cooling has to be accordingly compact and powerful. The target was to ensure sufficient cooling of both charge air and engine coolant also with very high ambient temperatures and permanent operation. KTR’s specialists were in charge of selecting this cooling system. Franz Fuchs, Project Manager of the new engine series with Hatz, explained: „We already involved KTR when we developed the engines, providing them with all details about thermal balance, ambient temperatures, volume, dimensions, etc.“
On this basis the specialists located in Rheine developed a customized or dual-circuit combined cooler specifically for the engine for cooling charge air and engine coolant. For dimensioning the respective cooling components the engineers, among others, make use of the simulation software „KULI“. Just as important is the experience of the persons in charge which is based on numerous projects for mobile and stationary applications in KTR.
Performance, mounting space, weight and volume as parameters
“Apart from sufficient cooling performance in any kind of application, dimensions and weight were vital factors for the development of the cooling system,” Friedrich Peter, head of engine designing with Hatz, explained, “Specifically with mobile applications the space is limited – that is why every centimetre counts. Weight is another key issue - That is why the combined cooler has a high power density and the box sizes of the OPU could be limited to 699 x 935 x 807 mm (length x width x height). Here the extremely low weight of the basic engine is beneficial: Having a weight of 255 kg the overall set exceeds the weight of the basic engine by 82 kg only.”
Subsequent to the common development all components of the OPU were tested on Hatz test benches during several thousand hours. Here potentials for optimization were identified and developed, always against the background of Hatz engines being globally known for a long service life, solidity and minimum service requirements. The cooling system meets this requirement.
Separate engine oil cooler and flange coupling on the driven side
There is no doubt that the combined cooler is KTR’s most concise and biggest system component on the OPU of series H by Hatz, but it is not the only one: A separate oil cooler having the dimensions of 150 x 150 x 70 mm is mounted on the engine side cooling the engine oil with the engine coolant.
If the engine is used as a primary unit of a hydrostatic drive, a KTR drive element on the flywheel side is supplied by the manufacturer or recommended to be mounted, respectively. In this case a BoWex® flange coupling is concerned ensuring the connection between flywheel and hydraulic pump. The curved-tooth gear coupling® serves for compensating for the misalignment in the drive train. Subject to its high torsion spring stiffness it furthermore makes sure that there is no generation of any critical resonances, thus considerably adding to protecting the adjacent components as well as the overall power pack. Here a BoWex® standard flange coupling type FLE-PA as a size T55 is used installed in a standard SAE connection housing.
The connection between I. C.-engine and hydraulic pump has quite short dimensions. The torsionally rigid and maintenance-free flange couplings of this series easy to install have been used on various hydrostatic drive systems for some decades. In contrast to the cooling systems where series H by Hatz represents the first cooperation with KTR, the company located in Rheine has supplied flange couplings to the Lower Bavarian manufacturer of diesel engines for many years already.
Author: Joachim Grunwald, Product Manager for mobile cooling systems in KTR Rheine