JP2010138773A - Reducing agent feeder for exhaust emission control catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reducing agent feeder for an exhaust emission control catalyst, improving fuel consumption by controlling such that a liquid reducing agent is maintained at a minimum appropriate temperature. <P>SOLUTION: A reducing agent tank 33 stores the liquid reducing agent supplied to the exhaust system 19 of an engine 15. A heat exchanger 35 is supplied with engine cooling water heated by heat exchange with the engine 15 and heats the liquid reducing agent in the reducing agent tank 33 through heat storage fluid 32. A radiator 18 cools the engine cooling water routed through the heat exchanger 35 and circulates it to the engine 15. The amount of engine cooling water returned from the engine 15 to the radiator 18 by bypassing the heat exchanger 35 is proportionally adjusted in a reducing direction by a solenoid proportional valve 38 when the amount of engine cooling water returned from the engine 15 to the radiator 18 through the heat exchanger 35 is proportionally adjusted in an increasing direction. A controller 43 adjusts the solenoid proportional valve 38 based on the temperature of the liquid reducing agent detected by a temperature detector 41 and controls the temperature of the liquid reducing agent constant. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust gas purifying catalyst reducing agent supply device for supplying an exhaust gas purifying catalyst reducing agent, which is kept warm by utilizing heat of engine cooling water, to an engine exhaust device.

  As a conventional technique for preventing freezing of a reducing agent used for exhaust purification of an engine, a liquid injected and supplied to an upstream side of an exhaust gas purification catalyst disposed in an exhaust system including an exhaust manifold, an exhaust pipe, and a muffler of an internal combustion engine A heat retention device that prevents the reducing agent from freezing in the supply pipe system including the storage tank and the pump, and the heating wire is arranged over the whole or the main part of the outer surface of the supply pipe system including the liquid reducing agent storage tank and the pump. In addition, a heating wire heating means is provided in the storage tank as necessary, and the heating wires are energized from an external power source according to the liquid reductant temperature and / or outside air temperature. Reducing agent heat retention device for engine exhaust gas purification catalyst, which is configured to cut off the energization and maintain the temperature of the liquid reductant in an appropriate temperature range to prevent freezing, and incorporating the same It is an exhaust gas purification device (e.g., see Patent Document 1).

In addition, there is an exhaust purification device in which a cooling water circulation pipe of an engine is connected to a reducing agent tank that stores the reducing agent to prevent the freezing of the reducing agent, and the cooling water heated by the engine is guided to the reducing agent tank. . This is provided with a cooling water shut-off valve in the middle of the cooling water circulation pipe, and this cooling water shut-off valve is controlled to open for a predetermined time under a specific condition by the control means so as to circulate the cooling water (for example, Patent Document 2).
JP 2000-027627 A (page 3, FIG. 1) Japanese Patent Laying-Open No. 2006-125331 (5th page, FIG. 2)

  When the prior art described in Patent Document 1 is applied to a working machine such as a hydraulic excavator, excessive power is required to prevent the liquid reducing agent in the tank from freezing, and the battery of the working machine such as a hydraulic excavator is used. Then, it is difficult to respond. In particular, when working machines are used in cold regions or highlands such as on a mountain, it is necessary to always warm the liquid reducing agent because the liquid reducing agent such as urea water may freeze and the pipe may burst. In addition, it is necessary to continuously drive the engine in order to constantly supply electric power, resulting in poor fuel consumption.

  Further, in the work machine, the engine load changes depending on the work content, and the engine coolant temperature changes significantly due to the engine load. Therefore, as in the prior art described in Patent Document 2, the engine load is changed in the middle of the coolant circulation pipe. In the case where a cooling water shut-off valve is provided, and the cooling water shut-off valve is controlled to circulate the cooling water by opening the cooling water shut-off valve for a predetermined time under specific conditions by the control means, the temperature of the liquid reducing agent is kept constant. Is difficult.

  The present invention has been made in view of the above points, and provides a reducing agent supply device for an exhaust gas purification catalyst that can improve fuel efficiency by controlling the liquid reducing agent so that it can be maintained at an appropriate minimum temperature. The purpose is to provide.

  According to the first aspect of the present invention, there is provided a reducing agent tank containing a liquid reducing agent supplied to an exhaust device of an engine and an engine cooling water heated by heat exchange between the engine and the inside of the reducing agent tank. The heat exchanger that warms the liquid reductant, the cooler that cools the engine coolant that has passed through the heat exchanger and circulates it to the engine, and the amount of engine coolant that is returned from the engine to the cooler through the heat exchanger A proportional proportional valve, a temperature detector for detecting the temperature of the liquid reducing agent, and a temperature of the liquid reducing agent by adjusting the electromagnetic proportional valve based on the temperature of the liquid reducing agent detected by the temperature detector. Is a reducing agent supply device for an exhaust gas purifying catalyst.

  According to a second aspect of the present invention, the electromagnetic proportional valve in the reducing agent supply device for the exhaust gas purifying catalyst according to the first aspect is provided in a conduit for supplying engine cooling water to the heat exchanger and is proportional to the command current. One solenoid proportional valve whose opening degree changes from the closed state to the open state, and the opening degree change from the open state to the closed state in proportion to the command current provided in the bypass pipe that does not pass through the heat exchanger It is a reducing agent supply apparatus for exhaust gas purification catalysts provided with the other electromagnetic proportional valve.

  The invention described in claim 3 is the regenerator supply device for exhaust gas purification catalyst according to claim 1 or 2, wherein the heat storage tank is filled with the heat storage fluid and the reductant tank is built in the heat storage fluid; A heat insulating tank that covers the outer surface of the heat storage tank, and the heat exchanger is provided inside the heat storage tank and receives supply of engine cooling water to indirectly heat the heat storage fluid in the heat storage tank, thereby reducing the reducing agent indirectly. It is a reducing agent supply device for an exhaust gas purification catalyst that warms a liquid reducing agent in a tank.

  According to the first aspect of the present invention, the controller adjusts the electromagnetic proportional valve based on the temperature of the liquid reducing agent detected by the temperature detector to heat the liquid reducing agent in the reducing agent tank. By controlling the amount of engine cooling water supplied to the vessel, the liquid reducing agent can be controlled so as to be maintained at an appropriate minimum temperature, and fuel efficiency can be improved. At this time, the controller adjusts the electromagnetic proportional valve based on the temperature of the liquid reducing agent detected by the temperature detector, and adjusts the amount of engine coolant supplied to the heat exchanger, thereby making the temperature of the liquid reducing agent constant. Because it controls, the heat dissipated from the engine can be recovered with the engine cooling water and effectively used for heat retention of the liquid reducing agent via the heat storage fluid, and at that time, the electromagnetic proportional valve is controlled by the controller and the temperature detector, The temperature of the liquid reducing agent can be maintained within an appropriate range.

  According to the second aspect of the present invention, in the case of proportionally adjusting the amount of engine coolant returned from the engine to the cooler through the heat exchanger by one electromagnetic proportional valve, the other electromagnetic proportional valve is used. Therefore, even when adjusting the amount of heat supplied from the heat exchanger to the heat storage fluid by proportionally adjusting the amount of engine coolant that bypasses the heat exchanger and returns to the cooler, the cooler The amount of engine coolant that passes through can be kept constant, and the cooling capacity of the cooler can be kept constant.

  According to the invention described in claim 3, a heat exchanger for warming the heat storage fluid is provided inside the heat storage tank whose outer surface is covered with a tank heat insulating material and filled with the heat storage fluid, and together with this heat exchanger Since the reductant tank that contains the liquid reductant supplied to the engine exhaust system is built in the heat storage fluid in the heat storage tank, a double tank of the tank heat insulating material and the heat storage fluid heated by the heat exchanger With the heat retaining structure, the reducing agent tank and the liquid reducing agent inside thereof can be efficiently warmed, and the thermal efficiency required for warming can be improved.

  Hereinafter, the present invention will be described in detail with reference to an embodiment shown in FIGS.

  As shown in FIGS. 2 and 3, a hydraulic excavator 10 as a work machine has a lower traveling body 11 provided with an upper revolving body 12 as a machine body so that the upper revolving body 12 can turn, and the upper revolving body 12 has a cab 13 and a working device. 14 and engine 15 are installed. The engine 15 includes an engine body 16 and a water jacket (not shown) for cooling the engine body 16.

  The engine 15 is provided with a cooling fan 17 on a rotating shaft projecting from one side of the engine body 16, and a radiator 18 as a cooler is disposed facing the cooling fan 17. An exhaust device 19 is disposed on the other side of the engine body 16 to silence and purify exhaust gas discharged from the engine 15.

  A counterweight 21 is attached to the rear end portion of the upper swing body 12. The counterweight 21 is a liquid such as urea water as a reducing agent for an exhaust gas purification catalyst that is kept warm using the heat of engine cooling water. A main part of an exhaust gas purifying catalyst reducing agent supply device 22 for supplying the reducing agent to the exhaust device 19 is incorporated.

  As shown in FIG. 1, hydraulic pumps 23 and 24 that supply hydraulic oil to the hydraulic motors of the lower traveling body 11 and the upper swing body 12 and the hydraulic cylinders of the work device 14 are connected to the output shaft of the engine 15. Has been. The exhaust device 19 of the engine 15 has a muffler body 26 connected to the engine body 16 via an exhaust pipe 25, an exhaust gas purification catalyst 27 inside the muffler body 26, and liquid reduction with respect to the exhaust gas purification catalyst 27 And a nozzle 28 for injecting the agent.

  The reducing agent supply device 22 for the exhaust gas purifying catalyst of the engine 15 is filled with a heat storage fluid 32 such as paraffin or emulsion (emulsified liquid) in the heat storage tank 31, and the exhaust device 19 of the engine 15 is filled in the heat storage fluid 32. A reductant tank 33 containing a liquid reductant supplied to the heat storage tank 31 is incorporated, and the outer surface of the heat storage tank 31 is covered with a tank heat insulating material 34 for keeping the heat storage fluid 32 warm. An inlet 33a for injecting a liquid reducing agent provided at the upper end of the reducing agent tank 33 is opened on the upper surface of the tank heat insulating material 34 and is closed by a cap 33b.

  In the heat storage fluid 32 of the heat storage tank 31, the heat exchanger that warms the liquid reductant in the reductant tank 33 by receiving the supply of engine cooling water heated by heat exchange with the engine 15 and warming the heat storage fluid 32 35 is arranged.

  The engine coolant circuit 36 for circulating the engine coolant operates in proportion to a water jacket (not shown) of the engine 15, an engine coolant pump 37 for circulating the engine coolant, and a command current supplied to the solenoid 38s1. One electromagnetic proportional valve 38-1, a heat exchanger 35 in the heat storage tank 31, and a radiator 18 as a cooler for cooling the engine cooling water that has passed through the heat exchanger 35 and circulating it to the water jacket of the engine 15 The pipes 39a and 39b are connected endlessly.

  Between the pipe line 39a between the engine coolant pump 37 and one electromagnetic proportional valve 38-1 and the pipe line 39b between the heat exchanger 35 and the radiator 18, these pipe lines 39a and 39b are provided. The other electromagnetic proportional valve 38-2 that is proportionally operated by a command current supplied to the solenoid 38s2 is also provided in the bypass conduit 39c.

  One electromagnetic proportional valve 38-1 changes its opening degree from the closed state to the open state in proportion to the command current supplied to the solenoid 38s1, and the other electromagnetic proportional valve 38-2 is supplied to the solenoid 38s2. The supply flow rate of the engine coolant supplied to the heat exchanger 35 is adjusted by changing the opening degree from the open state to the closed state in proportion to the command current.

  In short, the electromagnetic proportional valve 38, which is composed of one electromagnetic proportional valve 38-1 and the other electromagnetic proportional valve 38-2, controls the amount of engine cooling water returned from the engine 15 to the radiator 18 via the heat exchanger 35. When proportionally adjusting in the direction of increasing by the proportional valve 38-1, the amount of engine coolant returned from the engine 15 to the radiator 18 by bypassing the heat exchanger 35 is proportional to the direction of decreasing by the other electromagnetic proportional valve 38-2. To be adjusted.

  The illustrated electromagnetic proportional valve 38 includes two electromagnetic proportional valves 38-1 and 38-2, but may be configured as a single multi-way valve.

  This electromagnetic proportional valve 38 can adjust the amount of heat supplied from the heat exchanger 35 to the heat storage fluid 32 by changing the amount of engine cooling water to the heat exchanger 35, and also the amount of engine cooling water that passes through the radiator 18 at this time Can be kept constant, that is, the cooling capacity of the radiator 18 can be kept constant.

  A temperature detector 41 for detecting the temperature of the liquid reducing agent is connected to the reducing agent tank 33, and this temperature detector 41 is connected to a detection signal input unit of the controller 43 by a temperature detection line. The control signal output unit of the controller 43 is connected to the solenoids 38s1 and 38s2 of the two electromagnetic proportional valves 38-1 and 38-2 by the control signal lines 44 and 45, and the temperature of the liquid reducing agent in the reducing agent tank 33. The amount of engine coolant supplied to the heat exchanger 35 in the heat storage tank 31 is controlled by adjusting the opening of the two electromagnetic proportional valves 38-1 and 38-2 based on the It has a function of controlling the temperature of the liquid reducing agent to be constant by adjusting the amount of heat exchange.

  A reducing agent supply circuit 51 for supplying a liquid reducing agent to the exhaust device 19 of the engine 15 is provided with a reducing agent supply pump 53 in a reducing agent supply pipe 52 disposed from the reducing agent tank 33 to the nozzle 28 in the muffler body 26. And an electromagnetic valve 54 for adjusting the injection amount of the reducing agent.

  A heat storage fluid circulation circuit 55 that circulates the heat storage fluid 32 in the heat storage tank 31 is provided with a front half 56a of a heat storage fluid passage 56 that flows the heat storage fluid 32 so as to cover the outside of the reducing agent supply circuit 51. A heat storage fluid circulation pump 57 is provided in 56. The outer surface of the heat storage fluid passage 56 is covered with a circuit heat insulating material 58 over the entire length.

  Next, the operation of the embodiment shown in the drawings will be described.

  During engine operation, the engine coolant is circulated by the engine coolant pump 37, the heat of the engine coolant is supplied to the heat exchanger 35 in the heat storage tank 31, and the heat stored in the heat storage tank by the heat released from the heat exchanger 35. The heat storage fluid 32 in 31 is warmed, and the liquid reducing agent in the reducing agent tank 33 is kept at a constant set temperature.

  At this time, the temperature detector 41 detects the temperature of the liquid reducing agent, and the controller 43 controls the solenoids 38s1 and 38-2 of the solenoid proportional valves 38-1 and 38-2 according to the temperature difference between the detected temperature of the liquid reducing agent and the set temperature. The engine coolant supplied to the heat exchanger 35 is output by outputting a command current to 38s2 and controlling the opening of the solenoid proportional valves 38-1 and 38-2 in opposite directions in proportion to the current value. The amount of engine cooling water returned to the radiator 18 is controlled to a constant amount.

  For example, when the detected temperature of the liquid reducing agent in the reducing agent tank 33 is lower than the set temperature, the opening degree of one electromagnetic proportional valve 38-1 is increased according to the temperature difference between the detected temperature and the set temperature. By adjusting in the direction, the amount of engine coolant supplied to the heat exchanger 35 is increased in proportion to the temperature difference, and the other electromagnetic proportional valve 38-2 is adjusted in the direction to reduce the opening degree, By controlling the amount of engine cooling water bypassed by the bypass line 39c in proportion to the temperature difference, the amount of engine cooling water returned to the radiator 18 is controlled to be kept constant. As a result, the cooling capacity of the radiator 18 is kept constant.

  In addition, the heat storage fluid 32 in the heat storage tank 31 flows from the heat storage tank 31 by the heat storage fluid circulation pump 57 through the heat storage fluid passage 56 along the outer periphery of the reducing agent supply circuit 51 and circulates to the heat storage tank 31. The reducing agent supply circuit 51 is kept warm by the heat of the fluid 32, and the reducing agent supply circuit 53 keeps the liquid reducing agent supplied from the reducing agent tank 33 to the nozzle 28 by the reducing agent supply circuit 51.

  Since the liquid reducing agent is pressurized and supplied from the reducing agent tank 33 by the reducing agent supply pump 53 to the electromagnetic valve 54 via the reducing agent supply pipe 52, the controller 43 has an engine speed, exhaust temperature, etc. not shown. Based on these data, the amount of reducing agent injection is calculated, and the electromagnetic valve 54 is adjusted based on the calculation result to control the amount of reducing agent injection.

  Next, effects of the embodiment shown in the drawings will be described.

  The controller 43 adjusts the electromagnetic proportional valve 38 based on the temperature of the liquid reductant detected by the temperature detector 41 to the heat exchanger 35 that heats the liquid reductant in the reductant tank 33 via the heat storage fluid 32. By controlling the amount of engine coolant supplied, it is possible to control the liquid reducing agent so that it can be maintained at an appropriate minimum temperature, thereby improving fuel efficiency.

  At this time, the controller 43 adjusts the electromagnetic proportional valve 38 based on the temperature of the liquid reducing agent detected by the temperature detector 41 and adjusts the amount of engine coolant supplied to the heat exchanger 35, thereby Since the temperature is controlled to be constant, the heat radiated from the engine 15 can be recovered by the engine cooling water and effectively used to keep the liquid reductant through the heat storage fluid 32. At that time, the controller 43 and the temperature detector 41 By controlling the electromagnetic proportional valve 38, the temperature of the liquid reducing agent can be maintained within an appropriate range.

  In particular, when adjusting proportionally in the direction of increasing the amount of engine coolant returned from the engine 15 through the heat exchanger 35 to the radiator 18 by one electromagnetic proportional valve 38-1, the other electromagnetic proportional valve 38-2 Even when adjusting the amount of heat supplied from the heat exchanger 35 to the heat storage fluid 32 by proportionally adjusting the amount of engine cooling water returned from the engine 15 to the radiator 18 by bypassing the heat exchanger 35, the radiator The amount of engine coolant passing through 18 can be kept constant, and the cooling capacity of the radiator 18 can be kept constant.

  In addition, a heat exchanger 35 for warming the heat storage fluid 32 is provided in the heat storage tank 31 whose outer surface is covered with the tank heat insulating material 34 and filled with the heat storage fluid 32 therein. Since the reductant tank 33 containing the liquid reductant supplied to the exhaust device 19 of the engine 15 is incorporated in the heat storage fluid 32, the tank heat insulating material 34 and the heat storage fluid 32 heated by the heat exchanger 35 are stored. Due to the double tank heat insulation structure, the reducing agent tank 33 and the liquid reducing agent therein can be efficiently kept warm, and the thermal efficiency required for keeping warm can be improved.

  Further, a heat storage fluid circulation circuit 55 is provided so as to cover the outside of the reducing agent supply circuit 51 that supplies the liquid reducing agent to the exhaust device 19 of the engine 15, and the outside of the heat storage fluid circulation circuit 55 is covered by the circuit heat insulating material 58. The reductant supply circuit 51 can be efficiently warmed by the double circuit heat retaining structure of the heat storage fluid circulation circuit 55 and the circuit heat insulating material 58, and the thermal efficiency can be improved.

  The heat exchanger 35 that has received the supply of engine coolant heated by heat exchange with the engine 15 warms the heat storage fluid 32 in the heat storage tank 31 and warms the liquid reductant in the reductant tank 33 with the heat. Since the temperature is maintained, electricity is not required as in the prior art, and the heat of the engine coolant before being cooled by the radiator 18 is effectively used. This saves fuel and improves fuel consumption.

  By installing a reductant supply device 22 for exhaust gas purification catalyst such as a heat storage tank 31 that stores heat using a heat storage fluid 32 on a counterweight 21 in a work machine such as a hydraulic excavator, a large-capacity heat storage tank 31 can be installed. The liquid reductant can be kept warm for a long time by the heat storage fluid 32 having a large heat capacity.

  Since the counterweight 21 is adjacent to the close position behind the engine 15 and the exhaust device 19, the piping of the engine coolant circuit 36, the reducing agent supply circuit 51, and the heat storage fluid circulation circuit 55 can be easily disposed. Since the distance from the supply source to the supply destination is short, it is possible to effectively suppress the temperature drop of the engine cooling water, the liquid reducing agent, and the heat storage fluid 32 during supply.

  The present invention is a type in which the liquid reductant in the reductant tank 33 or on the outer surface of the reductant tank 33 receives the supply of engine cooling water that has absorbed heat released from the engine 15 and warms the liquid reductant. The heat exchanger (not shown) may be arranged. In this case, the heat storage tank 31 and the heat storage fluid 32 are not necessary.

  The exhaust gas purifying catalyst reducing agent supply device 22 of the present invention can be used for an engine used in a working machine such as a hydraulic excavator, an automobile, an industrial machine, and the like.

1 is a system configuration diagram showing an embodiment of a reducing agent supply device for an exhaust gas purification catalyst according to the present invention. It is a side view of the working machine provided with the reducing agent supply apparatus same as the above. It is a top view of the working machine provided with the reducing agent supply apparatus same as the above.

Explanation of symbols

15 engine
18 Radiator as a cooler
19 Exhaust system
22 Reductant supply device for exhaust gas purification catalyst
31 Thermal storage tank
32 Thermal storage fluid
33 Reductant tank
34 Tank insulation
35 heat exchanger
38 Solenoid proportional valve
38-1 One proportional solenoid valve
38-2 The other solenoid proportional valve
39a pipeline
39c Bypass line
41 Temperature detector
43 Controller

Claims (3)

A reducing agent tank containing a liquid reducing agent to be supplied to an engine exhaust device;
A heat exchanger that receives the supply of engine cooling water heated by heat exchange with the engine and warms the liquid reducing agent in the reducing agent tank;
A cooler that cools the engine coolant that has passed through the heat exchanger and circulates it in the engine;
An electromagnetic proportional valve for proportionally adjusting the amount of engine coolant returned from the engine to the cooler through the heat exchanger according to the command signal;
A temperature detector for detecting the temperature of the liquid reducing agent;
A reducing agent supply for an exhaust gas purification catalyst, comprising: a controller that adjusts an electromagnetic proportional valve based on the temperature of the liquid reducing agent detected by the temperature detector to control the temperature of the liquid reducing agent to be constant. apparatus. The solenoid proportional valve
One electromagnetic proportional valve that is provided in a pipe that supplies engine coolant to the heat exchanger and that changes in opening degree from a closed state to an open state in proportion to a command current;
2. The exhaust according to claim 1, further comprising: another electromagnetic proportional valve provided in a bypass pipe that does not pass through the heat exchanger and whose opening degree is changed from an open state to a closed state in proportion to a command current. Reducing agent supply device for gas purification catalyst. A heat storage tank in which the heat storage fluid is filled and a reducing agent tank is built in the heat storage fluid;
A tank insulation covering the outer surface of the heat storage tank,
The heat exchanger is provided inside the heat storage tank, receives the supply of engine cooling water, and warms the heat storage fluid in the heat storage tank to indirectly heat the liquid reductant in the reductant tank. 3. A reducing agent supply device for an exhaust gas purifying catalyst according to 1 or 2.

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