METHOD FOR COMBINED PREHEATING AND COOLING OF A COOLANT

Abstract

A method for cooling a coolant for waste heat cooling of an internal combustion engine is described for an agricultural working vehicle. The method includes providing a heat exchanger through which coolant flows and an air delivery means generates an air flow through the heat exchanger.

Description

RELATED APPLICATIONS

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.

FIELD OF THE DISCLOSURE

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.

BACKGROUND OF THE DISCLOSURE

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.

SUMMARY

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.

BRIEF DESCRIPTION OF THE DRAWINGS

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:

FIG. 1 is an agricultural working vehicle with a cooling system controlled according to one embodiment; and

FIG. 2 is an agricultural working vehicle with a cooling system controlled according to another embodiment.

Corresponding reference numerals are used to indicate corresponding parts throughout the several views.

DETAILED DESCRIPTION

FIG. 1 shows an agricultural working vehicle 12, depicted purely diagrammatically in parts, with a cooling system 10 arranged in a frontal area, for waste heat cooling of an internal combustion engine 20 placed in the engine bay 18. The agricultural working vehicle 12 furthermore may have a cab 14, a front axle 16 and a rear axle 22 driven by the internal combustion engine 20. A frame 24 serves a carrier element for the individual components of the working vehicle 12.

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.

In the illustrated embodiment shown in FIG. 1 and described herein, the fan 32 may be driven about a rotation axis D by a hydraulic motor 30, which in turn may be supplied by a hydraulic pump 26 driven by the internal combustion engine 20. According to this embodiment, it is proposed that the fan 32 can be driven by the hydraulic motor 30 both in the one rotation direction and in the opposite rotation direction as required. In another embodiment, the fan 32 may similarly be driven by an electric motor.

In FIG. 1, the air flow generated by the fan 32 is depicted by arrows which represent a flow direction of the air flow from the environment through the heat exchanger 28 and into the engine bay 18. The fan 32 is thus set and driven in the rotation direction in which, at least when the internal combustion engine 20 is at operating temperature, an air flow is generated which acts as a cooling air flow from the environment into the engine bay 18.

In FIG. 2, the fan 32 is set and driven in the opposite rotation direction, so that an air flow is generated out of the engine bay 18, through the heat exchanger 28 and into the environment. In this rotation direction, here called the opposite direction, the fan 32 is set to rotate in the opposite direction immediately after the cold start and during the subsequent warm-up phase of the internal combustion engine 20. The term “cold start” in the context of this application means a state in which a temperature level of the internal combustion engine 20, which is represented for example by the coolant temperature or the engine oil temperature, lies significantly below the operating temperature of the internal combustion engine 20, wherein the operating temperature is usually characterized by a coolant temperature between about 80° C. and 100° C. or an engine oil temperature between about 90° C. and 110° C.

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.

Claims

1. A method for combined preheating and cooling of a coolant for waste heat cooling of an internal combustion engine in an agricultural working vehicle, the method comprising:

providing a heat exchanger through which coolant flows and an air delivery means to generate an air flow through the heat exchanger;

generating air flow via the air delivery means in a direction towards or away from the internal combustion engine as required;

detecting a temperature of the internal combustion engine;

producing air flow in the direction away from the internal combustion engine when a temperature value of the internal combustion engine is below a threshold value; and

reversing the air delivery means when the temperature value exceeds the threshold value.

2. The method of claim 1, wherein the threshold value is established at a level of an operating temperature of the internal combustion engine.

3. The method of claim 1, wherein the air delivery means comprises a fan with an electric or hydraulic drive.

4. The method of claim 3, wherein the fan has fixed blades.

5. The method of claim 3, wherein the fan has variable pitch blades.