JP4852081B2 - Work machine with diesel engine - Google Patents

Description

  The present invention relates to a work machine with a diesel engine.

  In a working machine such as a construction machine, a diesel engine is widely used, but the exhaust gas of the diesel engine contains particulate matter. A filter is used to collect the particulate matter.

  This filter includes a continuous regeneration type filter. Continuously regenerating filters have both a function to collect particulate matter and a function to continuously regenerate the filter by oxidizing and removing the collected particulate matter by the action of a catalyst. An oxidation catalyst is supported on ceramics. For this reason, the particulate matter collected by the continuous regeneration type filter is continuously oxidized and removed by the action of the catalyst, and the filter is self-regenerated.

  This self-regeneration is not always good, and particulate matter gradually accumulates on the filter. When the amount of particulate matter deposited on the filter increases, the resistance when the exhaust gas passes through the filter increases, the pressure of the exhaust system increases, and the original performance of the engine cannot be obtained.

  On the other hand, Patent Document 1 discloses a technique for sensing engine exhaust pressure to warn of clogging of a filter.

JP 2005-299436 A

  However, since the technology described in Patent Document 1 senses engine exhaust pressure, it detects a stage where particulate matter has accumulated on the filter and the filter has been clogged to some extent.

  For this reason, it is necessary to perform forced regeneration to forcibly remove the particulate matter deposited on the filter.

  The forced regeneration is performed, for example, by performing fuel injection into the combustion chamber in the cylinder immediately before the exhaust valve is closed, separately from the normal fuel injection timing (near the top dead center of the compression stroke). Thereby, the fuel is discharged uncombusted outside the combustion chamber, supplied to the oxidation catalyst, and oxidized (burned). As a result, the temperature of the filter rises, the particulate matter collected by the filter is incinerated, and the filter is regenerated.

  On the other hand, if forced regeneration is performed each time a particulate matter is deposited on the filter in a predetermined amount or more, not only is extra fuel consumed, but there is an adverse effect such as early deterioration of engine oil.

  The present invention has been made in view of such a problem, and is a work machine with a diesel engine that can prevent the accumulation of particulate matter on a continuous regeneration filter and reduce forced regeneration. The issue is to provide.

  The work machine with a diesel engine according to the present invention is a work machine with a diesel engine provided with a diesel engine that drives a hydraulic pump, and is provided in an exhaust passage of the diesel engine, and particulate matter in the exhaust gas of the diesel engine And a filter carrying a catalyst that oxidizes the collected particulate matter, and a temperature sensor that measures the exhaust gas temperature of the diesel engine, and the exhaust gas measured by the temperature sensor When the gas temperature is equal to or lower than a predetermined temperature, the problem is solved by increasing the load of the diesel engine.

  The present invention employs a technique of detecting the exhaust gas temperature measured by the temperature sensor and increasing the load of the diesel engine when the detected exhaust gas temperature is lower than a predetermined temperature. As a result, the exhaust gas temperature can always be kept higher than the predetermined temperature. As a result, the catalyst supported on the filter is activated, and the particulate matter collected on the filter is immediately oxidized and removed. For this reason, the filter can always be kept in a state where almost no particulate matter is deposited, and there is almost no need for forced regeneration. Therefore, it is possible to prevent the disadvantages caused by the forced regeneration from occurring, and the diesel engine can always be operated in a good state.

The conditioned diesel engine working machine according to the present invention, intends line by increasing the discharge amount or discharge pressure of the hydraulic pump to increase the load of the diesel engine. When the discharge pressure of the hydraulic pump is increased, a switching control valve that controls a hydraulic actuator driven by the hydraulic pump, and a downstream outlet of a center bypass oil passage that passes through a neutral position of the switching control valve When the exhaust gas temperature measured by the temperature sensor is equal to or lower than a predetermined temperature, a cut valve that is provided in the open / close control and an engine controller that controls the rotational speed of the diesel engine to be constant, and the cut valve shuts off the center bypass oil passage, said to increase the discharge pressure of the hydraulic pump and configured to increase the load of the diesel engine.

In the case where the discharge amount of the hydraulic pump is increased, a negative control throttle provided at a downstream outlet of a center bypass oil passage that passes through a neutral position of the switching control valve that controls the hydraulic actuator, and the negative control A regulator that controls the discharge amount of the hydraulic pump controlled by the negative control pressure generated by the throttle, a relief valve that is provided in parallel with the negative control throttle and controls the relief pressure by the pilot pressure, and the rotational speed of the diesel engine An engine controller that controls the pressure of the relief valve to increase the pilot pressure applied to the relief valve when the exhaust gas temperature measured by the temperature sensor is equal to or lower than a predetermined temperature. Reduce the negative control pressure generated by the negative control throttle, The discharge rate of the hydraulic pump is increased by the regulator and configured to increase the load of the diesel engine.

  Further, when configured to increase the load of the diesel engine when the hydraulic actuator is not operated and when the diesel engine is idling, the particulates to the filter are not affected without affecting the original work of the work machine. Material deposition can be prevented.

  According to the present invention, it is possible to reduce the forced regeneration by preventing the accumulation of particulate matter on the continuous regeneration filter.

  Hereinafter, an example of a preferred embodiment of a work machine with a diesel engine according to the present invention will be described in detail based on the drawings.

  FIG. 1 is a block diagram showing a construction machine with a diesel engine according to a first embodiment of the present invention.

  The work machine 1 with a diesel engine includes a variable displacement hydraulic pump 10, a diesel engine 12 that drives the hydraulic pump 10, a regulator 14 that adjusts the discharge amount of the hydraulic pump 10, and hydraulic oil (pressure) Control valves 22, 24, 26 that control the direction, pressure, and flow rate of hydraulic oil (pressure oil) supplied to the hydraulic actuators 16, 18, 20. A continuously regenerating filter 28 that collects particulate matter in the exhaust gas discharged from the diesel engine 12 and purifies the exhaust gas, and a temperature sensor 30 that measures the temperature of the exhaust gas discharged from the diesel engine 12 And an engine controller 52 that controls the rotational speed of the diesel engine 12. In this embodiment, the temperature measurement by the temperature sensor 30 is performed only when the hydraulic actuators 16, 18, 20 are not operated and when the diesel engine 12 is idling.

  A cut valve 34 that can be opened and closed is provided at the downstream outlet of the center bypass oil passage 32, and a negative control throttle 36 and a relief valve 38 are provided in parallel at the downstream outlet of the cut valve 34, so that the center bypass oil passage is provided. A tank 40 is provided at the end of 32.

  The cut valve 34 is a two-position / two-port switching valve, has two switching positions A and B, and has ports P1 and P2. When the pilot pressure is not supplied to the pilot port 34a, the cut valve 34 is in the switching position A by the urging force of the spring 34b, and the ports P1 and P2 communicate with each other and the center bypass oil passage 32 communicates. In the state where the pilot pressure is supplied, the cut valve 34 is switched to the switching position B by being pushed by the pilot pressure, the ports P1 and P2 are not communicated, and the center bypass oil passage 32 is shut off.

  The electromagnetic switching valve 44 is a two-position / three-port switching valve, has two switching positions C and D, and has ports P3, P4, and P5. When the exhaust gas temperature measured by the temperature sensor 30 is equal to or lower than the predetermined temperature, the controller 46 indicates that the hydraulic actuators 16, 18, 20 are not operated and the diesel engine 12 is idling. After confirmation, an electrical signal is sent to the solenoid 44a of the electromagnetic switching valve 44. As a result, the switching position of the electromagnetic switching valve 44 becomes D, the ports P3 and P5 communicate, and the pilot pressure is supplied to the cut valve 34. In the state where the electric signal is not supplied to the solenoid portion 44a, the switching position of the electromagnetic switching valve 44 is C due to the urging force of the spring 44b, the ports P4 and P5 are connected, and the pilot pressure is not supplied to the cut valve 34.

  When the controller 46 determines that the exhaust gas temperature measured by the temperature sensor 30 is equal to or lower than a predetermined temperature, the hydraulic actuators 16, 18, 20 are not operated, and the diesel engine 12 is idling. After confirming this, an electric signal is sent to the solenoid portion 44a of the electromagnetic switching valve 44. This confirmation is intended to increase the engine load when the hydraulic actuators 16, 18, 20 are not operated and when the diesel engine 12 is idling. A monitor 48 is connected to the controller 46, and when an electrical signal is supplied from the controller 46 to the solenoid portion 44 a of the electromagnetic switching valve 44, the words “Self-reproducing” are displayed on the screen of the monitor 48. It is like that.

  The negative control pressure generated by the negative control throttle 36 acts on the regulator 14 via the negative control oil passage 50 to adjust the discharge amount by changing the tilt angle of the hydraulic pump 10.

  The rotational speed of the diesel engine 12 is controlled to a predetermined rotational speed by the engine controller 52 regardless of the load of the hydraulic pump 10. Therefore, when the discharge amount and / or discharge pressure of the hydraulic pump 10 increases and the load applied to the hydraulic pump 10 increases, the load of the diesel engine 12 also increases.

  The filter 28 is provided in the exhaust passage 12 </ b> A of the diesel engine 12. The filter 28 is a continuous regeneration type filter, and has both a function of collecting particulate matter and a function of continuously regenerating the filter by oxidizing and removing the collected particulate matter by the action of a catalyst. For example, an oxidation catalyst is supported on porous ceramics. For this reason, the particulate matter collected by the filter 28 is continuously oxidized and removed by the action of the catalyst, and the filter 28 is self-regenerated.

  A relief valve 64 is attached between the hydraulic pump 10 and the control valve 22 in parallel with the control valve 22 to define an upper limit value of the pressure of the center bypass oil passage 32.

  Next, the operation of the working machine 1 with a diesel engine according to the first embodiment configured as described above will be described.

  In order to operate the work machine 1 with a diesel engine, it is necessary to first drive the diesel engine 12 to drive the hydraulic pump 10 to supply hydraulic oil (pressure oil) to the center bypass oil passage 32. In this state, when the operator operates a control lever (not shown) and operates the control valves 22, 24, 26, the hydraulic oil supplied to the center bypass oil passage 32 is hydraulic actuators 16, 18 and 20. As a result, the hydraulic actuators 16, 18, and 20 are actuated to perform the intended work.

  When the diesel engine 12 is driven, exhaust gas containing particulate matter is exhausted. This exhaust gas is sent into the exhaust passage 12A, and when passing through the filter 28, particulate matter is collected and discharged to the outside. Is done.

  The filter 28 is a continuous regeneration filter, and the collected particulate matter is oxidized and removed by the catalyst supported on the filter 28, but the collected particulate matter is sufficiently oxidized and removed. This requires that the exhaust gas temperature reach a high temperature at which the catalyst is activated.

  Therefore, in this embodiment, the temperature sensor 30 measures the exhaust gas temperature, and the measurement result is sent to the controller 46 via the electric signal line 54. When the controller 46 detects that the exhaust gas temperature is equal to or lower than a predetermined temperature, the controller 46 sends an electric signal to the solenoid unit 44 a via the electric signal line 56. In the electromagnetic switching valve 44, the spool is moved downward in FIG. 1 in response to this electric signal, and the switching position is switched to D. Thereby, the ports P3 and P5 are communicated, and the pilot pressure from the pilot pump 42 is supplied to the pilot port 34a.

  When the pilot pressure is supplied to the pilot port 34a and the switching position of the cut valve 34 is switched to B, the ports P1 and P2 do not communicate and the center bypass oil passage 32 is shut off. For this reason, hydraulic oil (pressure oil) is not supplied downstream from the port P1, and the negative control pressure generated by the negative control throttle 36 is reduced. As a result, the negative control pressure acting on the regulator 14 via the negative control oil passage 50 decreases, the tilt angle of the hydraulic pump 10 increases, and the discharge amount of the hydraulic pump 10 increases. As a result, the pressure in the center bypass oil passage 32 increases to the relief pressure of the relief valve 64, and the discharge pressure of the hydraulic pump 10 increases.

  On the other hand, the diesel engine 12 is controlled by the engine controller 52 to have a predetermined rotational speed. For this reason, when the discharge amount and discharge pressure of the hydraulic pump 10 are increased and the load of the hydraulic pump 10 is increased, the load of the diesel engine 12 is increased, and the fuel supply amount is increased in order to keep the engine rotation speed constant. The exhaust gas temperature of the engine 12 rises.

  In the present embodiment, the exhaust gas temperature is maintained higher than a predetermined temperature by the mechanism described above. As a result, the catalyst supported on the filter 28 is activated, and the particulate matter collected on the filter 28 is immediately oxidized and removed. For this reason, in this embodiment, the filter 28 is kept in a state where the particulate matter is hardly deposited. Therefore, the frequency of forced regeneration with many disadvantages can be drastically reduced, and the diesel engine 12 can continue to operate in a good state.

  Next, a working machine with a diesel engine according to a second embodiment of the present invention will be described. FIG. 2 is a block diagram showing the construction machine with a diesel engine.

  The work machine 2 with a diesel engine according to the second embodiment is provided with a shuttle valve 60 in the middle of the negative control oil passage 50 of the first embodiment, and the negative control oil passage 50 is connected to one input port of the shuttle valve 60, and the shuttle The point which connected the pilot oil path 62 connected to the port P5 of the electromagnetic switching valve 44 to the other input port of the valve 60 differs from 1st Embodiment.

  Due to such a difference in configuration, in the work machine 2 with a diesel engine according to the second embodiment, the pressure in the negative oil passage 50 (negative control pressure) and the pressure in the pilot oil passage 62 (pilot pressure from the pilot pump 42) The greater pressure is introduced into the regulator 14.

  For this reason, even if the switching position of the cut valve 34 is B and the center bypass oil passage 32 is shut off and the negative control pressure is reduced, the regulator 14 has the pressure of the pilot oil passage 62 (the pilot pressure from the pilot pump 42). ) Is introduced, the discharge amount of the hydraulic pump 10 does not increase.

  However, since the center bypass oil passage 32 is blocked by the cut valve 34, the pressure in the center bypass oil passage 32 rises to the relief pressure of the relief valve 64, and the load applied to the hydraulic pump 10 increases. For this reason, the load applied to the diesel engine 12 increases, the exhaust gas temperature of the diesel engine 12 rises, and the particulate matter collected by the filter 28 is immediately oxidized and removed.

  As described above, in the work machine 2 with a diesel engine according to the second embodiment, the discharge pressure of the hydraulic pump 10 increases, but the discharge amount does not increase, and therefore, no useless flow rate is discharged.

  Next, a working machine with a diesel engine according to a third embodiment of the present invention will be described. FIG. 3 is a block diagram showing the construction machine with a diesel engine.

  The work machine 3 with a diesel engine according to the third embodiment is provided with a relief valve 70 that can remove the cut valve 34 of the first embodiment and can change the relief pressure by an external pilot pressure instead of the relief valve 38. This is different from the first embodiment.

  The pilot port 70a of the relief valve 70 and the port P5 of the electromagnetic switching valve 44 are connected by a pilot oil passage 72. When the switching position of the electromagnetic switching valve 44 becomes D, the pilot pressure is applied to the pilot port 70a, The relief pressure of the relief valve 70 is reduced, and the negative control pressure is reduced.

  For this reason, the controller 46 detects that the exhaust gas temperature is lower than a predetermined temperature, sends an electric signal to the solenoid unit 44a via the electric signal line 56, and the switching position of the electromagnetic switching valve 44 is changed. When switching to D, the pilot pressure from the pilot pump 42 is applied to the pilot port 70a of the relief valve 70 via the pilot oil passage 72, the relief pressure of the relief valve 70 is lowered, and the negative control pressure is lowered.

  For this reason, the negative control pressure acting on the regulator 14 via the negative control oil passage 50 is reduced, the tilt angle of the hydraulic pump 10 is increased, and the discharge amount of the hydraulic pump 10 is increased. As a result, the load applied to the diesel engine 12 increases, the exhaust gas temperature of the diesel engine 12 rises, and the particulate matter collected by the filter 28 is immediately oxidized and removed.

  On the other hand, in the work machine 3 with a diesel engine according to the third embodiment, the cut valve 34 is removed, and the center bypass oil passage 32 is not blocked by the cut valve 34 as in the first embodiment. The pressure in the bypass oil passage 32 rises only to the lower one of the relief pressure of the relief valve 64 and the relief pressure of the relief valve 70. For this reason, in the third embodiment, the pressure applied to the center bypass oil passage 32 can be suppressed.

  In the first and second embodiments described above, the degree of switching of the switching positions A and B of the cut valve 34 can be adjusted by the supplied pilot pressure, so the degree of shutoff of the center bypass oil passage 32 is determined by the exhaust gas temperature. Can be adjusted according to. As a result, for example, when the exhaust gas temperature is significantly lower than the predetermined temperature, the degree of shutoff by the cut valve 34 is increased to increase the amount of increase in engine load, and the exhaust gas temperature is slightly lower than the predetermined temperature. If it is lower, it can be controlled so that the degree of shutoff by the cut valve 34 is reduced to reduce the engine load increase amount, and the engine load increase amount is adjusted according to the exhaust gas temperature. You can also. In the third embodiment, since the relief pressure of the relief valve 70 can be adjusted by the supplied pilot pressure, the third embodiment also depends on the exhaust gas temperature as in the first and second embodiments. The amount of increase in engine load can be adjusted.

  The first to third embodiments described above are embodiments in which the present invention is applied to a hydraulic circuit using negative control control. However, when the exhaust gas temperature measured by the temperature sensor is equal to or lower than a predetermined temperature. The configuration for increasing the exhaust gas temperature by increasing the load of the diesel engine can also be applied to a hydraulic circuit using positive control control, a hydraulic circuit using load sensing control, and the like. Is not limited to a hydraulic circuit using negative control. When the present invention is applied to a hydraulic circuit in which load sensing control is used, it is possible to increase the load of the diesel engine by increasing the pump discharge amount while keeping the pump discharge pressure constant.

  Further, as in the above embodiment, the exhaust gas temperature measurement itself is performed when the hydraulic actuators 16, 18, 20 are not operated and when the diesel engine 12 is idling, and the hydraulic actuators 16, 18, 20 are not measured. When the load on the diesel engine 12 is increased at the time of operation and idling of the diesel engine 12, the load on the controller 46 can be reduced, and the filter 28 can be reduced without hindering the original work of the work machines 1, 2, and 3. It is possible to prevent the accumulation of particulate matter on the surface.

  It can be suitably used for a construction work machine using a diesel engine.

The block block diagram which shows the working machine with a diesel engine which concerns on 1st Embodiment of this invention. The block block diagram which shows the working machine with a diesel engine which concerns on 2nd Embodiment of this invention. The block block diagram which shows the working machine with a diesel engine which concerns on 3rd Embodiment of this invention.

Explanation of symbols

1, 2, 3 ... Work machine with diesel engine 10 ... Hydraulic pump 12 ... Diesel engine 12A ... Exhaust passage 14 ... Regulator 16, 18, 20 ... Hydraulic actuator 22, 24, 26 ... Control valve 28 ... Filter 30 ... Temperature sensor 32 ... Center bypass oil passage 34 ... Cut valve 36 ... Negative control throttle 38, 64 ... Relief valve 40 ... Tank 44 ... Electromagnetic switching valve 46 ... Controller 48 ... Monitor 50 ... Negative control oil passage 52 ... Engine controller 54, 56 ... Electric signal line 60 ... Shuttle valve 62, 72 ... Pilot oil passage 70 ... Relief valve

Claims (3)

In a work machine with a diesel engine equipped with a diesel engine that drives a hydraulic pump,
A filter that is provided in the exhaust passage of the diesel engine, collects particulate matter in the exhaust gas of the diesel engine, and carries a catalyst that oxidizes the collected particulate matter;
A temperature sensor for measuring the exhaust gas temperature of the diesel engine;
A switching control valve for controlling a hydraulic actuator driven by the hydraulic pump;
A cut valve that can be controlled to open and close, provided at a downstream outlet of a center bypass oil passage that passes through a neutral position of the switching control valve;
An engine controller for controlling the rotational speed of the diesel engine to be constant ,
When the exhaust gas temperature measured by the temperature sensor is equal to or lower than a predetermined temperature , the cut valve shuts off the center bypass oil passage, and increases the discharge pressure of the hydraulic pump to reduce the load on the diesel engine. A work machine with a diesel engine characterized by increasing. In a work machine with a diesel engine equipped with a diesel engine that drives a hydraulic pump,
A filter that is provided in the exhaust passage of the diesel engine, collects particulate matter in the exhaust gas of the diesel engine, and carries a catalyst that oxidizes the collected particulate matter;
A temperature sensor for measuring the exhaust gas temperature of the diesel engine;
A negative control throttle provided at a downstream outlet of a center bypass oil passage penetrating a neutral position of the switching control valve for controlling the hydraulic actuator;
A regulator that controls the discharge amount of the hydraulic pump controlled by the negative control pressure generated by the negative control throttle;
A relief valve provided in parallel with the negative control throttle, the relief pressure of which is controlled by a pilot pressure;
An engine controller for controlling the rotational speed of the diesel engine to be constant,
When the exhaust gas temperature measured by the temperature sensor is below a predetermined temperature, the pilot pressure applied to the relief valve is increased to reduce the relief pressure of the relief valve, and the negative control pressure generated by the negative control throttle is reduced. And increasing the load of the diesel engine by increasing the discharge amount of the hydraulic pump by the regulator . In claim 1 or 2,
A working machine with a diesel engine , wherein the load of the diesel engine is increased when the hydraulic actuator is not operated and when the diesel engine is idling .

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