Patent Application
20160102597
This application claims the benefit of German Application Ser. No. 102014220692.8, filed Oct. 13, 2014, the disclosure of which is hereby expressly incorporated by reference in its entirety.
The present disclosure relates to a method for cooling a coolant for waste heat cooling of an internal combustion engine in an agricultural working vehicle, wherein a heat exchanger through which coolant flows and an air delivery means to generate an air flow through the heat exchanger are provided.
Fluid-based cooling systems for waste heat cooling of an internal combustion engine are normally designed such that the cooling circuit is divided via a coolant thermostat into a secondary cooling circuit, also called the bypass circuit, and a main cooling circuit. In principle, during the warm-up phase, the coolant thermostat is in a position in which the flow of coolant in the main cooling circuit through the heat exchanger, also called the engine radiator, is blocked and a coolant flow through a coolant line bypassing the heat exchanger is opened. The associated reduction in circulated coolant leads to a faster passage through the warm-up phase, and the operating temperature of the internal combustion engine is reached earlier.
In the region of the so-called “switching temperature” of the coolant thermostat, the bypass coolant line is closed to the extent that the flow through the heat exchanger is opened. Also, coolant not yet heated is thus included in the coolant circuit and must be heated to a higher temperature. This leads to a brief fall in the temperature of the coolant circuit. Furthermore, the warm-up phase always lasts for a specific duration, whereas the temperature in the engine bay in which the internal combustion engine is placed exceeds the ambient temperature relatively soon after the cold start.
This disclosure provides a cooling system such that a further shortened warm-up phase of the internal combustion engine may be achieved.
In one embodiment, a method is provided for combined preheating and cooling of a coolant for waste heat cooling of an internal combustion engine in an agricultural working vehicle, wherein a heat exchanger through which coolant flows and air delivery means to generate an air flow through the heat exchanger are provided, and the air delivery means is configured to generate the air flow in a direction towards the internal combustion engine or in a direction away from the internal combustion engine as required, wherein the air delivery means is set to generate an air flow in the direction away from the internal combustion engine as long as a temperature value, which is characteristic of a temperature state of the internal combustion engine, lies below a threshold value, and the air delivery means is set reversed when the status value is exceeded.
In one non-limiting example, the method is advantageously able to exploit the temperature difference which can occur after a cold start of the internal combustion engine, during the warm-up phase between the ambient temperature and the engine bay temperature. Often, at the moment of cold start, the coolant in the heat exchanger is at the level of the ambient temperature. During the warm-up phase a temperature difference exists between the coolant in the heat exchanger and the engine bay. The method according to one example achieves that, on reaching the switching temperature of the coolant thermostat, i.e. on opening of the flow through the heat exchanger or the main cooling circuit, there is no or at least only a reduced brief temperature fall in the coolant circuit. Furthermore, the method shortens the duration of the warm-up phase since an additional heat input into the coolant circuit takes place during the warm-up phase. This heat input can come from a heat source, for example the exhaust manifold, the emitted heat of which is not normally used for any other purpose. To this extent, the efficiency of the internal combustion engine increases during the warm-up phase.
In one non-exclusive example, the threshold value is at the level of the operating temperature of the internal combustion engine. This ensures that as far as possible, the entire warm-up phase is used to guide air, which has already been heated in the engine bay, through the heat exchanger. In another non-exclusive example, the air delivery means is a fan with electric or hydraulic drive.
The above-mentioned aspects of the present disclosure and the manner of obtaining them will become more apparent and the disclosure itself will be better understood by reference to the following description of the embodiments of the disclosure, taken in conjunction with the accompanying drawings, wherein:
Corresponding reference numerals are used to indicate corresponding parts throughout the several views.
To dissipate the heat developed during operation of the internal combustion engine 20, the cooling system 10 may have a heat exchanger 28 through which coolant flows and over which air flows, and the air delivery means 32 generating the air flow, in the form of a fan. Both the heat exchanger 28 and the fan 32 may be arranged at the front of the internal combustion engine 20 in the travel direction of the working machine 12. The fan 32 may also be arranged between the internal combustion engine 20 and the heat exchanger 32.
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To perform the method according to one nonexclusive aspect of this disclosure, first a coolant temperature sensor, an engine oil temperature sensor and an external temperature sensor present on the agricultural working vehicle 12 detect whether a cold start state exists. If a cold start state exists, after the cold start of the internal combustion engine 20, the fan 32 is set and driven in the opposite direction of rotation so that an air flow is generated from the engine bay 18, through the heat exchanger 28 and into the environment. Since the exhaust manifold quickly becomes hot after a cold start of the internal combustion engine 20, this heats the engine bay 18 rapidly relative to the ambient temperature. This increased temperature is used to heat the coolant present in the heat exchanger 28 before the coolant thermostat has reached its switching temperature and opened the flow through the main cooling circuit. When the internal combustion engine 20 has reached its operating temperature, the rotation direction of the fan is reversed, and it is set and driven in the rotation direction in which an air flow is generated which acts as a cooling air flow out of the environment into the engine bay 18.
In other embodiments, a variable pitch blade fan with reversing capability may be used instead of a fixed blade fan. With a variable pitch blade fan, the direction of air flow can be reversed without reversing the direction of rotation of the motor.
While embodiments incorporating the principles of the present disclosure have been described hereinabove, the present disclosure is not limited to the described embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102014220692.8 | Oct 2014 | DE | national |
