JPH06146901A - Intake air heating system for diesel engine - Google Patents

Abstract

PURPOSE:To prevent the supercooling of intake air by regulating supply volume of cooling water for an intake air cooler during medium and heavy loads period in an intake air heating system of a main diesel engine. CONSTITUTION:A by-pass tube 4a branches off a cooling water supply tube 4 of an intake air cooler 3 provided on an intake air tube 2, and a mixed flow three-way regulating valve 1 is arranged at the connecting portion of an exit tube 4b and the by-pass tube 4a, an electromagnetic valve 5 is opened by a signal 6 of a main engine load in the case where the load for the main engine is a light load of 30% or less, and the flow of the cooling water for the intake air cooler 3 is shut off by opening the by-pass tube 4a by operating the regulating valve 1 by means of compressed working air 7, and the opening of the regulating valve 1 is adjusted so that the temperature of the intake air is kept constant in the case of medium and heavy loads by the signal from a temperature sensor 10. Thus, the supercooling of the intake air is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge air heating system for a diesel engine, and more particularly to a charge air heating system for a diesel engine which prevents supercooling of the charge air.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 4, in a charge air cooling system in a diesel main engine, an air charge pipe 2 of the engine is used.
Is provided with a charge air cooler 3. A cooling water supply pipe 4 and an outlet pipe 4b are connected to the supply air cooler 3, and in order to cut off the passage of the cooling water to the supply air cooler 3 during low load operation of the main engine, A bypass pipe 4a that bypasses the air cooler 3 is provided. Reference numeral 01 in FIG. 4 is provided in the middle of the outlet pipe 4b to connect the bypass pipe 4a to the outlet pipe 4a.
The piston type switching valve for switching and connecting to the downstream part 4c of b is shown. Reference numeral 5 denotes a solenoid valve which receives a solenoid valve switching signal 6'to switch the compressed air 7 for operation when the main engine has a low load (for example, 30% load).
01 is supplied to the working chamber 01a, and the switching valve 01 is connected to the bypass pipe 4
It connects a with the downstream portion 4c, and switches the outlet pipe 4b to the closed state. By this switching, the supply air cooler 3 is in a state in which the passage of cooling water is blocked.

[0003]

By the way, in the above-described conventional diesel engine charge air heating system, the ON / OFF control of the cooling water for the charge air cooler of the diesel main engine for heating the charge air is activated. Since compressed air 7 is supplied to the working chamber 01a of the piston-type switching valve 01 via the solenoid valve 5, cooling air is supplied when supply air heating is not required (when the main machine load is 30% or more). Flows into the charge air cooler 3, heat is exchanged more than necessary, and the temperature of the cooling water rises. As a result, the temperature of the cooling water supplied to another heat exchanger such as the oil cooler 8 arranged on the downstream side of the charge air cooler 3 becomes high, and the heat treatment capacity of the oil cooler becomes insufficient. is there. Further, if heat exchange is performed more than necessary in the charge air cooler 3, the temperature of the air supplied to the main engine will decrease, and as a result, the water content in the air will condense and form a drain that will flow into the engine, reducing engine performance. There is also the problem of making it worse.

The present invention is intended to solve the above-mentioned problems, and in the high load of the main engine without heating the supply air, the heat exchange in the supply air cooler is made appropriate, so that the supply air is improved. Equipped with a mixed flow type three-way adjusting valve that can control the amount of cooling water flowing to the air supply cooler so that the air temperature at the cooler outlet becomes constant, and this adjusting valve is detected by the temperature sensor installed in the air supply pipe. An object of the present invention is to provide a supply air heating system for a diesel engine, which is operated to prevent supercooling of the supply air and an increase in the temperature of the cooling water.

[0005]

In order to achieve the above object, a diesel engine charge air heating system of the present invention includes a diesel engine charge pipe, a charge air cooler provided in the charge pipe, and A cooling water supply pipe and an outlet pipe connected to the charge air cooler, and a bypass pipe connecting the cooling water supply pipe and the outlet pipe, the outlet pipe being upstream of the outlet pipe and the bypass pipe. , A mixed flow type three-way regulating valve having two inlets connected to each other and an outlet connected to the downstream side of the outlet pipe is interposed, while a temperature sensor is attached to the air supply pipe, During low-load operation of the engine, the mixed flow type three-way control valve is urged to communicate the outlet with only the inlet connected to the bypass pipe, and during other operations, the temperature sensor detects the temperature. Supply air temperature Based on the number, the opening degree is adjusted for the inlet connected to the upstream side of the outlet pipe of the mixed flow type three-way control valve so that the supply air inside the air supply pipe is maintained at a constant temperature. It is characterized by being adapted to be.

[0006]

In the supply air heating system for a diesel engine of the present invention described above, in an operating range where the engine load is low and supply air heating is required, the three-way regulating valve connects the bypass pipe to the downstream side of the outlet pipe to supply the air. Cut off the flow of cooling water to the air cooler. In addition, in the operating range except when the engine load is low, the flow rate to the charge air cooler is adjusted so that the charge air temperature in the charge air pipe is kept constant, so that the outlet pipe upstream of the outlet of the three-way regulating valve The degree of opening of the inlet connected to the side is adjusted.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A diesel engine charge air heating system as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of the system, FIG. 2 is a side sectional view of a regulating valve, and FIG. It is a graph shown. In addition, FIG.
The same reference numerals as in FIG. In the diesel engine charge air heating system of this embodiment as well, the charge air cooler 3 is provided in the charge pipe 2 of the diesel main engine,
A cooling water supply pipe 4 and an outlet pipe 4b are connected to the supply air cooler 3, and a bypass pipe 4a is further provided.

A mixed flow type three-way regulating valve 1 is provided at the connecting portion of the bypass pipe 4a, the outlet pipe 4b and the downstream side 4c of the outlet pipe. As shown in FIG. 2, the regulating valve 1 includes two inflow ports, which are formed at a lower portion of a main body of the regulating valve 1 at intervals in the vertical direction and are connected to the bypass pipe 4a and the water discharge pipe 4b, respectively. Has a discharge port which is formed substantially in the middle of the inflow port and is connected to the downstream side 4c.

Further, a diaphragm chamber 1A is provided at the upper end of the main body.
The valve rod 1B is attached to the diaphragm 1F stretched in the diaphragm chamber 1A, and the valve having the valve discs 1C and 1D is attached to the lower end portion of the valve rod 1B. Further, the valve rod 1B is urged by a spring 1E so as to press the valve body 1C against the valve seat and close the inflow port to which the bypass pipe 4a is connected. A control air introduction pipe 12 is connected to the lower chamber of the diaphragm chamber 1A.

Further, a temperature sensor 10 is attached to the air supply pipe 2 in order to measure the air supply temperature at the outlet of the air supply cooler 3. The supply air temperature signal obtained by the temperature sensor 10 is transmitted to the controller 9 via the lead wire 13. The control air introduction pipe 12 is connected to the supply source of the compressed air 7 for operation through the solenoid valve 5, and the solenoid valve 5 is connected to the solenoid 5a by the main machine load signal 6 when the load of the main engine is 30% or less. When energized, the working compressed air 7 is supplied to the control air introduction pipe 12, and when the load of the main engine exceeds 30%, the energization of the solenoid 5a is cut off and the control air from the controller 9 is passed through the communication pipe 11. The supply source of the compressed air to the control air introduction pipe 12 is switched by supplying the pressure air to the control air introduction pipe 12 via the control air introduction pipe 12.

In the above construction, when the main engine load is within 30%, the solenoid valve 5 operates so as to supply the working air 7 to the control air introduction pipe 12 by the main machine load signal 6. The control valve is in the state shown in FIG. 2 when the control air is not introduced into the diaphragm chamber 1A, but when the operation air 7 is supplied to the diaphragm chamber 1A by the above-described operation of the solenoid valve 5, The valve rod 1B of the regulating valve 1 moves upward against the pressing force of the spring 1E to connect the bypass pipe 4a to the downstream side 4c and close the outlet pipe 4b. As a result, the passage of cooling water to the supply air cooler 3 is cut off. Therefore, the supply air is not cooled.

When the load on the main engine exceeds 30%, the solenoid valve 5 is operated by the load signal 6 on the main engine so as to connect the control air introduction pipe 12 to the communication pipe 11. As a result, control air is supplied to the diaphragm chamber of the regulating valve 1 via the controller 9, and the opening of both valve bodies 1C and 1D in the regulating valve 1, that is, the amount of cooling water flowing to the charge air cooler 3 is Regulated by control air. The controller 9 is provided to automatically adjust the opening degree of the control valve 1 based on the supply air temperature signal from the temperature sensor 10 so that the supply air temperature becomes constant, and is supplied from the controller 9. The opening degree of each valve body 1C, 1D of the regulating valve 1 is adjusted by the control air, whereby the amount of cooling water flowing into the supply air cooler 3 is adjusted and the supply air temperature is kept constant. Will be kept. Further, by suppressing excessive heat exchange in the supply air cooler 3, it is possible to prevent the temperature rise of the cooling water.

FIG. 3 shows the effect of the present system. In FIG. 3, the horizontal axis shows the load of the main engine, the vertical axis shows the supply air temperature at the outlet of the supply air cooler, and the line Y shows the system. , And line Z is the characteristic in the conventional system. Point X is a supply air heating switching point. The shaded portion in FIG. 3 corresponds to the portion where the heat exchange is improved more than necessary. Needless to say, by setting the set value of the controller to an arbitrary value, it is possible to control the supply air temperature to be optimum for engine performance.

[0014]

As described in detail above, the following effects and advantages can be obtained by the supply air heating system for a diesel engine of the present invention. (1) In an operating range where the main engine load is low and heating of the supply air is required,
The flow of cooling water to the charge air cooler is cut off. (2) In the operating range where the main engine load is not low except when the load is low, the opening of the three-way control valve is adjusted so that the supply air outlet temperature of the supply air cooler is constant, and Supercooling can be prevented and the temperature rise of the cooling water can be suppressed.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a diesel engine charge air heating system according to an embodiment of the present invention.

FIG. 2 is a side sectional view of the adjusting valve.

FIG. 3 is a graph showing the same effect.

FIG. 4 is a schematic view of a conventional diesel air supply heating system.

[Explanation of symbols]

 1 Mixed flow type three-way regulating valve 1A Diaphragm chamber 1B Valve rod 1C, 1D valve 1F Diaphragm 2 Air supply pipe 3 Air supply cooler 4 Cooling water supply pipe 4a Bypass pipe 4b Outlet pipe 5 Solenoid valve 5a Solenoid 6 Main machine load signal 7 Operation compression Air 9 Controller 10 Temperature sensor 11 Communication pipe 12 Control air introduction pipe 13 Lead wire

Claims (1)

[Claims] 1. In a diesel engine, an air supply pipe of the diesel engine, and an air supply cooler provided in the air supply pipe,
A cooling water supply pipe and an outlet pipe connected to the same charge air cooler, and a bypass pipe connecting the cooling water supply pipe and the outlet pipe, the outlet pipe being upstream of the outlet pipe and the bypass pipe. A mixed flow type three-way regulating valve having two inflow ports connected to each of the pipes and an outflow port connected to the downstream side of the outlet pipe is provided, while a temperature sensor is attached to the air supply pipe. During low load operation of diesel engine,
The mixed flow type three-way control valve is urged to communicate the outlet with only the inlet connected to the bypass pipe, and at the time of other operation, based on the supply air temperature signal detected by the temperature sensor. In order to maintain the air supply inside the air supply pipe at a constant temperature, the opening of the outlet of the mixed flow type three-way control valve is adjusted with respect to the inlet connected to the upstream side of the outlet pipe. The air supply heating system for diesel engines, which is characterized by