JP2015166560A - Hydraulic control device for service vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To incinerate and remove particulate matter deposited at a diesel particulate collection filter utilizing increased temperature of exhaust gas caused by an increased engine load.SOLUTION: Selector valves 23a, 23b in pathways extending from center bypass circuits 18a, 18b to shuttle valves 21a, 21b are closed through operation of a switch 25 to thereby avoid a transmittance of a negative control pressure from the center bypass circuits 18a, 18b to the shuttle valves 21a, 21b and at the same time the shuttle valves 21a, 21b are changed over to the operating state by selector valves 22a, 22b, and at that time, a pilot pressure supplied from a pilot pressure adjusting valve 10 is transmitted to negative control segments 7a, 7b to thereby cause the pilot pressure input to the negative control segments 7a, 7b to be decreased and a pump discharging amount of variable capacity pumps 3a, 3b to be increased and then particulate matter at a diesel particulate collection filter 24 is incinerated and removed by increasing exhaust gas temperature.

Description

  The present invention relates to a hydraulic control device for a work vehicle, and more particularly to an improvement in a hydraulic control device for a work vehicle provided with a diesel particulate collection filter for removing particulate matter in an exhaust path of a diesel engine.

To incinerate and remove particulate matter deposited on diesel particulate filter (DPF), shut off the center bypass circuit by operating the cut valve provided in the hydraulic center bypass. Reduces the negative control pressure, changes the tilt angle of the swash plate hydraulic pump that controls the regulator according to the negative control pressure, increases the pump discharge amount of the hydraulic pump and increases the pump discharge pressure, diesel engine The particulate matter accumulated on the diesel particulate filter is incinerated and removed by the increase of the exhaust temperature of the diesel engine due to the increase in the load of the diesel engine. In addition to these operations, the negative control pressure and the pilot pressure Select a high pressure with the shuttle valve and By entering the regulator, the pump discharge pressure alone is increased without increasing the pump discharge volume, increasing the load on the diesel engine, and the particulate matter accumulated on the diesel particulate filter is incinerated by the rise in exhaust temperature. Patent Document 1 proposes a device that can be removed.
In addition, the relief pressure of the relief valve attached to the center bypass circuit can be adjusted, and when removing particulate matter by incineration, the relief pressure of the relief valve is lowered to reduce the pressure of the negative control circuit, and according to the negative control pressure Particles accumulated on the diesel particulate filter by changing the tilt angle of the swash plate type hydraulic pump controlled by the regulator, increasing the pump discharge amount of the hydraulic pump, and raising the exhaust temperature of the diesel engine Patent Document 1 proposes a substance that is removed by incineration.
In the invention described in Patent Document 1, the processing operation for forcibly carrying out incineration removal of particulate matter is performed when the diesel engine is in an idling state and the exhaust gas temperature of the diesel engine is lower than a set value. Only to be implemented.

Further, Patent Document 2 proposes a structure in which the switching operation of the cut valve is slowed down in the configuration of Patent Document 1 to smoothly reduce the pressure of the negative control circuit, that is, increase the load of the diesel engine.
In Patent Document 2, in addition to the exhaust gas temperature of the diesel engine described above, the engine speed and the engine boost pressure are used as conditions for performing the processing operation for forcibly removing the particulate matter by incineration. The point to do is disclosed.
Further, Patent Document 2 discloses that a pressure sensor is installed before and after sandwiching the diesel particulate filter for estimating the engine load and the pressure deviation between the upstream and downstream of the diesel particulate filter is detected. ing.

  In addition, unburned fuel is supplied into the exhaust pipe and burned by using a fuel injection device for regeneration, and the exhaust temperature is raised to remove the particulate matter deposited on the diesel particulate filter by incineration. And an operation for supplying unburned fuel into the exhaust pipe and an increase in exhaust temperature as disclosed in Patent Documents 1 and 2 are used to raise the exhaust temperature and deposit on the diesel particulate filter. Patent Document 3 proposes a method in which particulate matter that is removed by incineration is removed.

  However, in any case, the tilt angle of the variable displacement pump is adjusted by a single regulator, and there is no one corresponding to a hydraulic control device having a power shift function.

  As a hydraulic control device having a power shift function, in particular, a hydraulic control device including a power shift control unit and a negative control control unit, the hydraulic control device disclosed in Patent Document 4 is already known.

  This type of hydraulic control device includes a power shift control unit that receives a pilot pressure supplied from a pilot pressure adjusting valve and adjusts a discharge amount of a variable displacement pump, and a hydraulic pressure that is driven by hydraulic oil discharged from the variable displacement pump. A negative control control unit that adjusts the discharge volume of the variable displacement pump in response to the negative control pressure from the system center bypass circuit, but the hydraulic control valve driven by the variable displacement pump is neutral In this state, that is, in the situation where the negative control pressure of the hydraulic system is higher than the pilot pressure supplied from the pilot pressure regulating valve, the negative control control unit functions preferentially and the tilt angle of the variable displacement pump Since it changes in the direction of decreasing the discharge amount, the diesel engine that drives the variable displacement pump Gin load does not increase and exhaust temperature does not increase. In short, particulate matter accumulated on the diesel particulate filter can be incinerated and removed by increasing exhaust temperature due to increased diesel engine load. Inconveniences such as difficulty may occur.

Japanese Patent No. 4852801 (paragraph 0035, FIG. 1, paragraphs 0041-0042, FIG. 2, FIG. 3, paragraph 0009) Patent No. 4944152 (paragraph 0041, FIG. 2, FIG. 3, FIG. 4, paragraphs 0039-0040) JP 2013-108502 A (paragraph 0035, FIG. 1, paragraphs 0050 to 0051, FIG. 9) Japanese Patent No. 4667083 JP 2001-254681 A

  Therefore, an object of the present invention is to easily remove particulate matter deposited on a diesel particulate filter by using an increase in exhaust temperature accompanying an increase in the load of a diesel engine even in a hydraulic control device having a power shift function. Another object of the present invention is to provide a hydraulic control device for a work vehicle that can be removed by incineration.

The hydraulic control device for a work vehicle in the present invention has a diesel particulate filter for removing particulate matter in the exhaust path of a diesel engine,
By adjusting the pump discharge amount of the variable displacement pump by following the change in the pump discharge pressure of the variable displacement pump driven by the diesel engine, the output of the variable displacement pump is maintained at a set value and for output selection. Driven by hydraulic power discharged from the variable displacement pump and a power shift control unit that changes the set value of the output of the variable displacement pump by adjusting the pump discharge amount of the variable displacement pump in response to pilot pressure A pilot pressure that selects a high-pressure side pressure as a pilot pressure candidate for flow rate adjustment from the negative control pressure from the center bypass circuit of the hydraulic system and the pilot pressure for output selection supplied from the electromagnetic control type pilot pressure adjustment valve The pressure selected as a candidate by the selection means and the pilot pressure selection means is adjusted in flow rate. A first switching means for switching the operating state of the pilot pressure selecting means to either an operating state for outputting the pilot pressure as a pilot pressure or a non-operating state for outputting the negative control pressure as a pilot pressure for flow rate adjustment, and the pilot pressure An operation including a negative control control unit for adjusting the pump discharge amount of the variable displacement pump in a direction to decrease the pump discharge amount of the variable displacement pump in accordance with an increase in the pilot pressure for flow rate adjustment output from the selection means A hydraulic control device for cars,
In order to achieve the object, in particular,
A normally-opening type second switching means arranged on the pressure transmission line from the center bypass circuit to the pilot pressure selection means to open and close the line;
And a combustion regeneration function start switch that forcibly closes the second switching means and forcibly activates the pilot pressure selection means by the first switching means. .

With the above configuration, when the combustion regeneration function start switch is in the non-operating state and the pilot pressure selecting unit is switched to the non-operating state by the first switching unit, the electromagnetically controlled pilot The pilot pressure for output selection supplied from the pressure regulating valve is supplied to the power shift control unit, and normal power shift control is performed in the same manner as in the past.
In contrast, when the combustion regeneration function start switch is in the non-operating state and the pilot pressure selecting means is switched to the operating state by the first switching means, the hydraulic system center bypass circuit Of the negative control pressure and the pilot pressure for output selection are selected and supplied to the negative control controller as a pilot pressure for flow rate adjustment.
When the particulate matter is forcibly removed by incineration, the operator operates the combustion regeneration function start switch and is provided on the pressure transmission line from the center bypass circuit to the pilot pressure selection means. In addition, the normally open type second switching means is closed to prevent the negative control pressure from the center bypass circuit from being transmitted to the pilot pressure selecting means, and the pilot pressure selecting means is forced by the first switching means. To the operating state.
As a result of the negative control pressure from the center bypass circuit not being transmitted to the pilot pressure selection means, the pilot pressure selection means in the operating state is supplied with the pilot pressure for output selection supplied from the electromagnetic control type pilot pressure adjustment valve on the high pressure side. The pilot pressure for output selection supplied from the electromagnetic control type pilot pressure adjustment valve is input to the negative control control unit as the pilot pressure for flow rate adjustment.
Therefore, even when the hydraulic control valve driven by the variable displacement pump is in a neutral state, that is, even when the negative control pressure of the hydraulic system is high, the negative control control unit inputs The pilot pressure for flow rate adjustment can be reduced to the pilot pressure for output selection supplied from an electromagnetically controlled pilot pressure adjustment valve.
Accordingly, the pump discharge amount of the variable displacement pump increases more than when the combustion regeneration function start switch is not operated, that is, when the negative control pressure of the hydraulic system is input to the negative control controller, and the diesel engine that drives the variable displacement pump Since the load will increase, the particulate matter accumulated on the diesel particulate filter installed in the exhaust path of the diesel engine can be incinerated and removed by the rise of the exhaust temperature of the diesel engine. Become.
At this time, the energy consumed by the operation of the variable displacement pump, that is, the product of the internal pressure of the center bypass circuit of the hydraulic system and the pump discharge amount per unit time in the variable displacement pump is the load acting on the diesel engine.
The pump discharge amount is specified by the pilot pressure for output selection supplied from the electromagnetic control type pilot pressure adjustment valve. By controlling the electromagnetic control type pilot pressure adjustment valve, the particulate matter can be incinerated and removed. A suitable load can be applied to the diesel engine.
The combustion regeneration function start switch may be automatically switched instead of being operated by an operator.

Further, in place of the second switching means, provided is a normally open type second switching means for opening and closing the pipeline on the pressure transmission pipeline from the pilot pressure selection means to the negative control control unit,
Instead of the combustion regeneration function start switch, a combustion regeneration function start switch that forcibly closes the second switching means may be provided.

When such a configuration is applied, when the operator operates the combustion regeneration function start switch, the normally open type second switching means provided on the pressure transmission line from the pilot pressure selection means to the negative control control unit Is closed, and the pilot pressure for adjusting the flow rate output from the pilot pressure selecting means is not transmitted to the negative control control unit.
Therefore, even when the hydraulic control valve driven by the variable displacement pump is in a neutral state, that is, even when the negative control pressure of the hydraulic system is high, the negative control control unit inputs The pilot pressure for adjusting the flow rate can be reduced to an atmospheric pressure equivalent.
Accordingly, the pump discharge amount of the variable displacement pump increases more than when the combustion regeneration function start switch is not operated, that is, when the negative control pressure of the hydraulic system is input to the negative control controller, and the diesel engine that drives the variable displacement pump Since the load will increase, the particulate matter accumulated on the diesel particulate filter installed in the exhaust path of the diesel engine can be incinerated and removed by the rise of the exhaust temperature of the diesel engine. Become.
At this time, the energy consumed by the operation of the variable displacement pump, that is, the product of the internal pressure of the center bypass circuit of the hydraulic system and the pump discharge amount per unit time in the variable displacement pump is the load acting on the diesel engine.
Under this circumstance, the restriction of the pump discharge amount of the variable displacement pump by the negative control control unit is released, so the energy consumed by the operation of the variable displacement pump, that is, the load acting on the diesel engine is the power at that time. This is the maximum load in the pump control horsepower diagram according to the operation state of the shift control unit, that is, the operation state of the power shift control unit controlled by the pilot pressure for output selection supplied from the electromagnetic control type pilot pressure adjusting valve.

The hydraulic control apparatus for a work vehicle according to the present invention forces a normally open type second switching means provided on a pressure transmission line from the center bypass circuit to the pilot pressure selection means by operating the combustion regeneration function start switch. The negative control pressure from the center bypass circuit of the hydraulic system driven by the hydraulic oil discharged from the variable displacement pump driven by the diesel engine is prevented from being transmitted to the pilot pressure selection means, The pilot pressure selecting means is forcibly switched to the operating state by the first switching means for switching the operating state of the pilot pressure selecting means, and the pilot pressure for output selection supplied from the electromagnetically controlled pilot pressure adjusting valve at that time Is transmitted to the negative control controller as pilot pressure for flow rate adjustment Therefore, even when the hydraulic control valve driven by the variable displacement pump is neutral, that is, even when the negative control pressure of the hydraulic system is high, it is input to the negative control control unit. The pilot pressure for flow rate adjustment can be reduced to the pilot pressure for output selection supplied from the electromagnetically controlled pilot pressure adjustment valve.
Accordingly, the pump discharge amount of the variable displacement pump increases more than when the combustion regeneration function start switch is not operated, that is, when the negative control pressure of the hydraulic system is input to the negative control controller, and the diesel engine that drives the variable displacement pump Since the load will increase, the particulate matter accumulated on the diesel particulate filter installed in the exhaust path of the diesel engine can be incinerated and removed by the rise of the exhaust temperature of the diesel engine. Become.
The energy consumed by the operation of the variable displacement pump at this time, that is, the product of the internal pressure of the center bypass circuit of the hydraulic system and the pump discharge amount per unit time in the variable displacement pump is the load acting on the diesel engine, and the pump discharge Since the amount is specified by the pilot pressure for output selection supplied from the electromagnetic control type pilot pressure adjustment valve, it is suitable for incineration removal of particulate matter by controlling the electromagnetic control type pilot pressure adjustment valve. A load can be applied to the diesel engine.
In addition, since it is not necessary to install special hardware for realizing manual regeneration again except for the second switching means, it is possible to provide a hydraulic control device having a manual regeneration function at low cost.

In addition, a normally open type second switching means is provided on the pressure transmission line from the pilot pressure selection means to the negative control control unit, and a combustion regeneration function start switch for forcibly closing the second switching means is provided. With the above configuration, the normally-opening second switching means provided on the pressure transmission line from the pilot pressure selecting means to the negative control control section is closed by operating the combustion regeneration function start switch. Since the pilot pressure for adjusting the flow rate output from the pilot pressure selection means is not transmitted to the negative control control unit, the hydraulic control valve driven by the variable displacement pump is in a neutral state, that is, the hydraulic pressure Even when the negative control pressure of the system is high, it is input to the negative control control section. It can be lowered until the corresponding atmospheric pilot pressure for flow rate adjustment that.
Accordingly, the pump discharge amount of the variable displacement pump increases more than when the combustion regeneration function start switch is not operated, that is, when the negative control pressure of the hydraulic system is input to the negative control controller, and the diesel engine that drives the variable displacement pump Since the load increases, the particulate matter deposited on the diesel particulate collection filter installed in the exhaust path of the diesel engine can be incinerated and removed by the increase in the exhaust temperature of the diesel engine.
The energy consumed by the operation of the variable displacement pump at this time, that is, the product of the internal pressure of the center bypass circuit of the hydraulic system and the pump discharge per unit time in the variable displacement pump is the load acting on the diesel engine. Below, the restriction on the pump displacement of the variable displacement pump by the negative control controller is released, so the energy consumed by the operation of the variable displacement pump, that is, the load acting on the diesel engine, is the power shift control at that time. This is the maximum load in the pump control horsepower diagram corresponding to the operating state of the power shift control unit controlled by the operating state of the power control unit, that is, the pilot pressure for output selection supplied from the electromagnetically controlled pilot pressure regulating valve.
In addition, since it is not necessary to install special hardware for realizing manual regeneration again except for the second switching means, it is possible to provide the hydraulic control device 1 having a manual regeneration function at low cost.

It is a functional block diagram showing the outline of the composition of the hydraulic control device of one embodiment to which the present invention is applied. It is a functional block diagram showing the principal part of the controller which controls each part of the hydraulic control device of the embodiment. It is the flowchart shown about the outline of the power shift program performed by CPU with which the hydraulic control apparatus of the embodiment is provided. It is the conceptual diagram which showed an example of the normal power shift. It is the conceptual diagram which showed the range of the power shift expanded to the low output side in addition to the relationship between the pump discharge pressure and pump discharge amount at the time of applying a normal power shift. It is the conceptual diagram which showed the relationship between the pilot pressure with respect to a negative control control part, and pump discharge amount. It is the conceptual diagram which showed an example of the file stored in ROM. It is the conceptual diagram which showed an example of the power shift characteristic which restrict | limited the upper limit of pump discharge amount significantly. It is the conceptual diagram which showed an example of the file required in order to restrict | limit the upper limit of pump discharge amount. It is the functional block diagram which showed the outline of the structure of the hydraulic control apparatus of other one Embodiment to which this invention is applied.

  Next, some embodiments of a hydraulic control device for a work vehicle (hereinafter simply referred to as a hydraulic control device) in the present invention will be specifically described with reference to the drawings.

[First Embodiment]
FIG. 1 is a functional block diagram showing a hydraulic control apparatus 1 according to an embodiment to which the present invention is applied.

The hydraulic control device 1 includes variable capacity pumps 3a, 3b and a fixed flow rate control pump 4 driven by a diesel engine 2 for a work vehicle in which a diesel particulate filter 24 is built in an exhaust path of the engine, for example, a muffler. Have.
The hydraulic control device 1 includes a control valve group 5 that is a hydraulic system driven by hydraulic oil delivered from the variable displacement pumps 3a and 3b, power shift control units 6a and 6b, and negative control control units 7a and 7b. The adjusting means 9a, 9b for adjusting the pump discharge amount of the variable displacement pumps 3a, 3b by operating the tilting disks 8a, 8b according to the operating state of the power shift control units 6a, 6b and the negative control control units 7a, 7b. In addition, pilot pressure adjustment is performed based on information such as the rotational speed of the diesel engine 2 input via an electromagnetically controlled pilot pressure adjusting valve 10 and an engine control unit 17 for engine control (hereinafter simply referred to as ECU 17). A controller (Automatic Power Controller) 11 that controls the valve 10 is provided.

  The diesel particulate filter 24 is a filter for scavenging particulate matter contained in the exhaust gas of the diesel engine 2 to reduce the release of particulate matter into the atmosphere, and has a function due to clogging of the filter. In order to prevent the decrease, it is sometimes necessary to forcibly burn off particulate matter deposited on the filter with the heat of exhaust gas from the diesel engine 2. In general, this operation is called manual regeneration or forced regeneration.

The adjusting means 9a for adjusting the pump discharge amount of the variable displacement pump 3a in the hydraulic control device 1 includes a piston member 12a having large and small pressure receiving surfaces at both ends, and actuators of the power shift control unit 6a and the negative control control unit 7a. It is constituted by a control valve 13a that is pressed at the tip and shifts in the left-right direction in FIG.
FIG. 1 shows a state in which the spool of the control valve 13a is in the neutral position. In this state, the hydraulic oil in the oil chamber 14a in which a large-diameter pressure receiving surface formed at the right end of the piston member 12a is fitted is shown. Since entry / exit is prohibited, the piston member 12a is held in a fixed position, the tilt of the tilting disc 8a is held in the current position, and the pump discharge amount of the variable displacement pump 3a is maintained in the current state.
Further, when the spool of the control valve 13a is shifted to the right in FIG. 1, the hydraulic oil is allowed to enter and leave the oil chamber 14a fitted with a large-diameter pressure receiving surface formed at the right end of the piston member 12a. At the same time, hydraulic oil delivered from the variable displacement pump 3a flows into an oil chamber 15a fitted with a small diameter pressure receiving surface formed at the left end of the piston member 12a, and the piston member 12a is moved to the right in FIG. The tilting disc 8a swings in the clockwise direction, and the pump discharge amount in the variable displacement pump 3a increases.
Further, when the spool of the control valve 13a is shifted to the left side in FIG. 1, the hydraulic oil sent from the variable capacity pump 3a flows into both the oil chamber 14a and the oil chamber 15a, but both ends of the piston member 12a. 1, the piston member 12a shifts to the left in FIG. 1, and the tilting plate 8a swings in the counterclockwise direction to reduce the pump discharge amount in the variable displacement pump 3a. .

The power shift control unit 6a of the hydraulic control device 1 holds the output of the variable displacement pump 3a in the vicinity of the set value by using the function of the adjusting unit 9a described above, and further, the control pump 4 is used as a drive source. This is for controlling the power shift by changing the set value of the output of the variable displacement pump 3a by adjusting the pump discharge amount with the pilot pressure for output selection supplied from the pilot pressure adjusting valve 10 that performs the operation. .
That is, the piston member 16a constituting the actuator of the power shift control unit 6a is formed with three pressure receiving surfaces, one of which receives the pressure of the hydraulic oil sent from the variable displacement pump 3a, The other one receives the pressure of the hydraulic fluid sent from the variable displacement pump 3b, and shifts the spool of the piston member 16a and further the spool of the control valve 13a to the left in FIG. 1, thereby moving the piston member 12a in FIG. By moving the tilting plate 8a to the left and swinging the tilting disk 8a in the counter clockwise direction to limit the pump discharge amount of the variable displacement pump 3a, the pump discharge amount is decreased and variable according to the increase of the pump discharge pressure. The output of the displacement pump 3a, that is, the integrated value of the pump discharge pressure and the pump discharge amount is held near the set value, and at the piston member 16a, By the applied override pilot pressure for the output selection supplied from the pilot pressure control valve 10 to the pressure receiving surface is configured to output set value shift itself of the variable displacement pump 3a.
At this time, the magnitude of the pilot pressure for output selection supplied from the pilot pressure adjusting valve 10 is automatically calculated by the controller 11 that controls the pilot pressure adjusting valve 10 based on information such as the engine speed, A power shift is made according to the deviation between the engine speed and the actual engine speed.

The negative control controller 7a of the hydraulic control device 1 uses the throttle valve 19a and the relief valve 27a provided at the end of the hydraulic system including the control valve group 5 in the basic power shift control to control the variable displacement pump 3a. By receiving the negative control pressure generated in the center bypass circuit 18a on the side and operating the piston member 20a using this pressure as a pilot pressure for adjusting the flow rate, the function of the adjusting means 9a described above is used. The discharge amount is adjusted.
If the pilot pressure for flow rate adjustment input to the negative control controller 7a increases, the spool of the piston member 20a and further the control valve 13a shifts to the left in FIG. 1, and the piston member 12a moves to the left in FIG. And the tilting platen 8a swings in the counterclockwise direction to reduce the pump discharge amount of the variable displacement pump 3a. When the pilot pressure for flow rate adjustment decreases, the piston member 20a and further the spool of the control valve 13a 1 shifts to the right in FIG. 1, the piston member 12a moves to the right in FIG. 1, and the tilting platen 8a swings in the clockwise direction, thereby limiting the pump discharge amount of the variable displacement pump 3a. Canceled.

  Actually, the negative control controller 6a and the power shift controller 7a function simultaneously, but as shown in FIG. 1, the piston member 16a of the negative control controller 6a and the piston member 20a of the power shift controller 7a are Since the variable displacement pump 3a is provided in parallel to the control valve 13a of the adjusting means 9a, the pump discharge amount of the variable displacement pump 3a results in a piston member that functions as an actuator on the side where the pump discharge amount is largely limited. 16a or the piston member 20a is limited by receiving a command from the control unit 6a or 7a on the side where the piston member 20a is protruded a lot.

  The variable displacement pump 3b, the power shift control unit 6b, the negative control control unit 7b, and the adjustment unit 9b have the same configuration as the variable displacement pump 3a, the power shift control unit 6a, the negative control control unit 7a, and the adjustment unit 9a. Therefore, only the reference numerals corresponding to the respective parts in FIG. 1 are attached, and detailed description thereof is omitted.

  The pilot pressure selecting means in this embodiment is constituted by shuttle valves 21a and 21b, and the first switching means for switching the pilot pressure selecting means between the operating state and the non-operating state is constituted by switching valves 22a and 22b. Further, the second switching means is constituted by switching valves 23a and 23b.

Specifically, one input port of the shuttle valve 21a serving as the pilot pressure selecting means is connected to the center bypass circuit 18a on the variable capacity pump 3a side via the switching valve 23a serving as the normally open second switching means. On the other hand, the other input port of the shuttle valve 21a can be brought into and out of contact with the pilot pressure regulating valve 10 via the switching valve 22a which is the first switching means, and the switching valve 23a which is the second switching means is provided. When the switching valve 22a, which is the first switching means, is activated and shifts to the left in FIG. 1 under the open condition, that is, the other input port of the shuttle valve 21a is connected to the pilot pressure adjusting valve 10. In this case, the pilot pressure for selecting the output supplied from the pilot pressure adjusting valve 10 and the pilot for adjusting the flow rate supplied from the center bypass circuit 18a are used. The magnitude relation between the pressure is compared by the shuttle valve 22a, a relatively high pilot pressure is supplied to the negative control controller 7a. This state is defined as the operating state of the shuttle valve 21a serving as a pilot pressure selection means.
Further, as shown in FIG. 1, when the switching valve 22a, which is the first switching means, is in an inactive state under the condition that the switching valve 23a, which is the second switching means, is open, the center bypass circuit 18a Since the pressure to be compared with the pilot pressure for flow rate adjustment, that is, the pressure to be compared with the negative control pressure, is the atmospheric pressure, the shuttle valve 21a serving as the pilot pressure selection means is for adjusting the flow rate supplied from the center bypass circuit 18a. Is constantly selected as the pilot pressure on the high pressure side. This state is defined as a non-operating state of the shuttle valve 21a serving as a pilot pressure selection means.
Therefore, the shuttle valve 21a is used for adjusting the flow rate between the negative control pressure from the hydraulic center bypass circuit 18a and the pilot pressure for output selection supplied from the electromagnetic control type pilot pressure adjusting valve 10 on the high pressure side. Pilot pressure selection means for selecting pilot pressure candidates, and the switching valve 22a is in an operating state of the shuttle valve 21a as pilot pressure selection means, that is, a state in which the pilot pressure on the high-pressure side is selected and output; In other words, it is a first switching means for switching to a non-operating state, that is, a state in which the gate control pressure supplied from the center bypass circuit 18a is constantly selected.
The switching valve 23a is arranged on the pressure transmission line from the hydraulic center bypass circuit 18a to the shuttle valve 21a, which is a pilot pressure selection means, and is a normally open second type that opens and closes the line. Switching means.

  Since the configurations and functions of the shuttle valve 21b, the switching valve 22b, and the switching valve 23b disposed on the variable displacement pump 3b side are the same as those of the shuttle valve 21a, the switching valve 22a, and the switching valve 23a, detailed description thereof is omitted. .

Further, the hydraulic control apparatus 1 of this embodiment includes a pressure sensor 26a for detecting the pump discharge pressure of the variable displacement pump 3a and a pressure sensor 26b for detecting the pump discharge pressure of the variable displacement pump 3b, and a muffler in the exhaust path. In the diesel particulate filter 24 built in, etc., a differential pressure sensor 28 for detecting a deviation between the exhaust pressure at the front stage and the exhaust pressure at the rear stage is installed.
The configuration and operation of the differential pressure sensor 28 are already known in Japanese Patent No. 4944152, but in this embodiment, the differential pressure sensor 28 is used to detect the degree of clogging of the diesel particulate filter 24. Therefore, its use is different from the conventional example.

In the present embodiment, the switching valve 23a constituting the second switching means is forcibly closed, and the switching valve 22a constituting the first switching means is operated so that the pilot pressure selecting means A combustion regeneration function start switch 25 for forcibly switching a certain shuttle valve 21 a to an operating state is provided connected to the controller 11.
The installation destination of the combustion regeneration function start switch 25 itself is, for example, around the instrument panel in the cabin of the work vehicle.

  FIG. 2 is a functional block diagram showing the main part of the controller 11 that controls each part of the hydraulic control device 1.

The main part of the controller 11 is a microprocessor 29 for arithmetic processing (hereinafter simply referred to as CPU), a read-only memory 30 (hereinafter simply referred to as ROM 30) storing a control program for the CPU 29, and arithmetic data It is composed of a random access memory 31 (hereinafter simply referred to as RAM 31) used for temporary storage and the like, and is supplied by a manual regeneration command sent from the combustion regeneration function start switch 25 by the operator's manual operation or by pressure sensors 26a and 26b. Deviation between the detected pump discharge pressure of the variable displacement pumps 3a and 3b and the exhaust pressure before and after the diesel particulate filter 24 detected by the differential pressure sensor 28, that is, the degree of clogging of the diesel particulate filter 24. The value representing the Read the CPU29 in real time through the circuit 32, and the value of the engine speed of the diesel engine 2 is adapted to be loaded into CPU29 in real time via the input circuit 32 and ECU 17.
The engine accelerator command value is a signal from a throttle opening sensor provided in the diesel engine 2.
Further, the switching valves 22a and 22b functioning as the first switching means, the switching valves 23a and 23b functioning as the second switching means, and the pilot pressure adjusting valve 10 are driven and controlled by the CPU 29 via the output circuit 33 of the controller 11. On the display 34 installed around the instrument panel in the cabin of the work vehicle together with the combustion regeneration function start switch 25, various alerts and alerts related to alarms are displayed in response to commands from the CPU 29. It is like that.

  FIG. 3 is a flowchart showing an outline of a power shift program repeatedly executed at predetermined intervals by the CPU 29 of the controller 11, and the contents are stored in the ROM 30.

  In this embodiment, the relationship between the engine engine speed and the engine engine speed is considered in consideration of the torque characteristics of the diesel engine 2 and the loads of the variable displacement pumps 3a and 3b. In the region of the engine speed in which the above problem does not occur, a normal power shift using the power shift control units 6a and 6b is performed in the same manner as a conventional hydraulic control device such as the hydraulic control device disclosed in Japanese Patent Laid-Open No. 2001-254681, etc. In the low-speed rotation region where the engine speed is low and the engine torque decreases and problems such as engine stall occur, the negative control control units 7a and 7b are forcibly operated to further reduce the power to the low output side. A shift is performed.

  The CPU 29 of the controller 11 that has started the processing of FIG. 3 first determines whether or not the value “2” indicating that manual regeneration is being executed is set in the state storage flag F that stores the execution state of manual regeneration and the like. However, since the value of the state storage flag F is held at the initial value “0” at this stage, the determination result in step S1 is false.

  Next, the exhaust pressure deviation detected before and after the diesel particulate filter 24 detected by the differential pressure sensor 28, that is, a value representing the degree of clogging of the diesel particulate filter 24 is read and temporarily stored (step). S2) Further, it is determined whether or not the value “1” for requesting execution of manual regeneration is set in the state storage flag F for storing the execution state of manual regeneration, etc. (step S3). Since the value of the state storage flag F is held at the initial value “0”, the determination result in step S3 is false.

Further, the ECU 17 changes the engine speed R _n temporarily stored in the process of step S2 from a table (not shown) storing the correspondence relationship between the threshold value of the exhaust pressure deviation to be regarded as occurrence of clogging and the engine speed. A corresponding determination threshold for manual regeneration is selected (step S4), and the magnitude relation with the exhaust pressure deviation temporarily stored in the process of step S2 is compared (step S5).

  If the determination result in step S5 is true, the exhaust gas pressure deviation value at the present time does not reach the determination threshold for manual regeneration, that is, particles currently deposited on the diesel particulate filter 24. This means that it is not necessary to forcibly burn off the particulate matter with the heat of the exhaust gas of the diesel engine 2.

  As described above, since normal operation is possible under the condition where particulate matter is not deposited on the diesel particulate filter 24, first, processing related to power shift will be described.

For example, assuming that the threshold value of the engine speed is R _S and switching between normal power shift and low output side power shift, the CPU 29 first executes the power shift program of FIG. compares the magnitude relation between the temporarily stored engine speed R _n and the threshold value R _S in the processing of step S2 (step S16), and if the engine speed R _n is above the threshold R _S, the first switch switching valves 22a constituting the means 22b are inoperative state as shown in FIG. 1 (step S19), similarly to the conventional driving the pilot pressure regulating valve 10 based on the information of the engine speed R _n current to adjust the magnitude of the pilot pressure for the output selection supplied from the pilot pressure control valve 10 by applying a power shift corresponding to the engine speed R _n Execute (Step S20).

As described above, when the switching valves 22a and 22b constituting the first switching means are inactivated as shown in FIG. 1, the shuttle valves 21a and 21b constituting the pilot pressure selection means are The pilot pressure for flow rate adjustment supplied from the bypass circuits 18a and 18b is steadily selected as the pilot pressure on the high pressure side, and the pilot pressure for output selection supplied from the pilot pressure adjustment valve 10 is a power shift control unit. Since it acts only on 6a and 6b, the hydraulic control device 1 of this embodiment functions in exactly the same way as a conventional input torque control circuit, and can perform a power shift in the range of section X in FIG. .
FIG. 4 is a conceptual diagram showing an example of a normal power shift. F _{0 in} FIG. 4 is a case where the pilot pressure for output selection supplied from the pilot pressure adjusting valve 10 is minimized, that is, the limit is set. A function representing the relationship between the pump discharge pressure P and the pump discharge amount Q at the maximum output, and f _max is the maximum when the pilot pressure for output selection supplied from the pilot pressure adjusting valve 10 is maximized. It is a function representing the relationship between the pump discharge pressure P and the pump discharge amount Q at the minimum output after power shift. Since the piston member 12a for operating the tilting disc 8a can be continuously moved in the left-right direction in FIG. 1, the set value of the output of the variable displacement pump 3a is within the range of the section X in FIG. However, the power shift limit is complicatedly related to the size of the three pressure receiving surfaces of the piston member 16a and the elastic force of the in-situ return spring in the piston member 16a and the control valve 13a. Therefore, in a conventional hydraulic control device such as that disclosed in Japanese Patent Application Laid-Open No. 2001-254681, the power shift range cannot be expanded beyond the section X.

  Next, the operation principle in the case of performing a power shift to the low output side beyond the normal power shift range will be described.

FIG. 5 is a conceptual diagram showing, on the same scale as FIG. 4, the range of the power shift expanded to the low output side in addition to the relationship between the pump discharge pressure P and the pump discharge amount Q when a normal power shift is applied. Similarly to the case of FIG. 4, functions f ₀ and f _max representing a limit of a normal power shift and a selectable power shift range X are described. FIG. 6 is a conceptual diagram showing the relationship between the pilot pressure R and the pump discharge amount Q with respect to the negative control controllers 7a and 7b. The relationship between the pilot pressure R and the pump discharge amount Q is described by a function g.

Now, if, over the range of the interval X in FIG. 5, and would like to power shift to the lower output relationships of the pump delivery pressure P and the pump discharge quantity Q to the position indicated by the function of the f _i in FIG .
At this time, for example, in order to realize the output at the point f _{i, j} on the function f _i in FIG. 5, theoretically, the pump discharge pressure is set to P _{i, j} and the pump discharge amount is set to Q _{i, j.} However, such an output state is impossible in the normal power shift section X to which the power shift by the power shift control units 6a and 6b is applied. However, the pump discharge amount Q _{i, j} required corresponding to the pump discharge pressure P _{i, j} is within the range of pump discharge amount control using the negative control control units 7a, 7b shown in FIG. Therefore, by setting the pilot pressure for the negative control controllers 7a and 7b to R _{i, j} , it is possible to realize the pump discharge amount Q _{i, j} required for realizing the output at f _{i, j} . .
Similarly, point _f i on the function _{f i} in FIG. _{5, j = f i, 0} ~f i, because all _m is not only to be reproduced, for example, as shown in FIG. 7 Then, the pilot pressure R _{i, j} for the negative control controller 7a, 7b required to realize the pump discharge pressure P _{i, j} and the pump discharge pressure P _{i, j} for all of j = 0 to _m. , And stored as a file in the ROM 30 functioning as a non-volatile storage means, the current value P of the sum of pump discharge pressures is detected by the pressure sensors 26a and 26b, and the pump substantially matches the current value P the discharge pressure P _i, searches the _j from a file, such as in FIG. 7, as the pump discharge pressure P _i, the pilot pressure R _i corresponding to _{j, j} is applied the negative control controller 7a, and 7b It is sufficient to proportional control pilot pressure supplied from the current clogging pilot pressure regulating valve 10 to be applied to the pilots pressure regulating valve 10.
Incidentally, if the value of m is a number of divisions of functions f _i is finite, i.e., the pump discharge pressure P _{i, j} and the pump discharge pressure P _i, if _{the j + 1} becomes discontinuous, the current pump discharge pressure either pump discharge pressure P _i the value P is stored in the _file, does not necessarily exactly match the _j, usually before or after the pump to sandwich the current value P of the pump discharge pressure discharge pressure P _{i, j} and P _{i, j + 1} and the pilot pressures R _{i, j} and R _{i, j + 1} corresponding to these are obtained from the file as shown in FIG. 7, and further, proportional distribution processing is performed to obtain the current value of the pump discharge pressure. A pilot pressure R strictly corresponding to P is obtained.
Specifically, an arithmetic expression of R = R _{i, j} + [(P−P _{i, j} ) / (P _{i, j + 1} −P _{i, j} )] · (R _{i, j + 1} −R _{i, j} ) The pilot pressure R may be obtained by executing proportional distribution using it.
Alternatively, the function f _i and the function g itself are stored in the ROM 30 as a nonvolatile storage means, and the pump discharge amount Q required by substituting the current value P of the pump discharge pressure into the function f _i , Further, the pilot pressure R may be obtained by substituting the pump discharge amount Q into the function g.

That is, in this embodiment, in the power shift program of FIG. 3 that is repeatedly executed at predetermined intervals, when the engine speed R _n is equal to or less than the threshold value R _S and the determination result in step S16 is true, that is, diesel This is the first switching means only when the torque output of the engine 2 is insufficient and it is considered that problems such as engine stall will occur if the output of the variable displacement pumps 3a, 3b is adjusted within the range of the normal power shift X. The switching valves 22a and 22b are shifted from the non-actuated state as shown in FIG. 1, and the other input ports of the shuttle valves 21a and 21b are connected to the pilot pressure regulating valve 10 (step S17). In order to realize the pump discharge amount Q corresponding to the current value P of the pump discharge pressure detected at 26a, 26b, a negative control Control unit 7a, 7b are stored pilot pressure R that is required ROM30 functioning as nonvolatile storage means file or, determined from the function f _i and the function g, a pilot current the pilot pressure R is sent By applying the pressure adjusting valve 10 and supplying the pilot pressure R to the negative control controllers 7a and 7b, the power shift to the lower output side beyond the normal power shift range X, for example, in FIG. realizing power shift as shown in the function _{f i} (step S18). Under the situation where the current value R _n of the engine speed is less than the threshold value _RS , the pilot pressure R for output selection supplied from the pilot pressure adjusting valve 10 is inevitably generated from the center bypass circuit 18a of the control valve group 5. Since it becomes higher than the negative control pressure, as a result, the shuttle valve 21a functioning as a pilot pressure selection means selects the pilot pressure R for output selection, and this pilot pressure R is used for the flow rate adjustment to the negative control controller 7a. It is supplied as pilot pressure.

In short, the file shown in FIG. 7 is the relationship between the pump discharge pressure P _{i, j} and the pump discharge amount Q _{i, j} desired when realizing the power shift as shown by the function f _i in FIG. the pump discharge pressure _{P i, j} and the pump discharge pressure _{P i,} the pump discharge quantity _{Q i} corresponding to _j, negative control control unit 7a to meet _j, 7b pilot pressure _{R i need,} the _j It is a file stored as a relationship, and is actually required as data to be registered in the ROM 30 when performing a data search operation based on the current value P of the pump discharge pressure detected by the pressure sensors 26a and 26b. Only the required _{Pi, j} column and the corresponding pilot pressure _{Ri, j} column.

  Further, the CPU 29 that executes the process of step S18 obtains the pilot pressure R required by the negative control controllers 7a and 7b from the file based on the pressure P detected by the pressure sensors 26a and 26b, and the pilot pressure R It functions as a control means for controlling the pilot pressure adjusting valve 10 so that it is output, and the processing of this step S18 is executed when the shuttle valves 21a, 21b, which are pilot pressure selection means, are in an activated state. Limited to.

Here, as an example, while indicating embodiments of the normal low output side of the power shift beyond the limits of the power shift only one as a function f _i in FIG. 5, in fact, of the diesel engine 2 rpm R Any number of functions for realizing the power shift on the low output side according to _n can be stored.
For example, a file having a larger pilot pressure R _{i, j} than the file shown in FIG. 7 is provided in parallel with the file of FIG. 7 and R under the condition of threshold R _S ′ <threshold R _{S. If} the file of FIG. 7 is selected under the condition of _S ′ <R _n ≦ R _S and the other file is selected under the condition of R _n <R _S ′, the rotational speed R of the diesel engine 2 _A two-stage power shift is possible depending on _n .

Further, as shown in FIG. 5, not only the function f _i having the same characteristic as the output characteristic in the normal power shift range X is shifted in parallel but also the output characteristic in the normal power shift range X. It is possible to set functions having different output characteristics. For example, as shown in FIG. 8, it is also possible to newly generate a function h that greatly limits the upper limit of the pump discharge amount Q.
In the example shown in FIG. 8, it is necessary to limit the pump discharge amount Q so that it is constantly Q _max ′ when the pump discharge pressure P is equal to or less than P _{mid, and} as is apparent from the characteristics of FIG. In the file as shown in FIG. 9, all the values of R _max ′ are stored in the terms R _{i, 0 to} R _{i, j} corresponding to the section in which the term P _{i, j} is equal to or less than P _mid. Become.

  The characteristics shown in FIG. 8 are such that when a crane work or breaker work is performed with a power shovel, that is, the pump discharge amount Q is greatly limited to stabilize the behavior of the actuator and fine work. This is useful when

Whether CPU29 selects which files when executing the processing of step S18, other methods such as to automatically perform the selection process within the process of CPU29, subject to engine speed R _n, a manual operation panel or the like Since it is possible to connect and select a file by a manual command, a file for realizing the output characteristics as shown in FIG. 8 and a file for realizing the output characteristics as shown in FIG. It is possible to realize various output characteristics by causing the CPU 29 to select a file automatically or by any manual operation, without causing any inconvenience in living in the ROM 30.

  If the determination result in step S5 described above becomes true, the exhaust pressure deviation value at the present time exceeds the determination threshold value for manual regeneration, that is, it accumulates on the diesel particulate filter 24. This means that it is necessary to forcibly burn and remove the particulate matter with the heat of exhaust gas from the diesel engine 2, so the CPU 29 outputs an alert display signal to the display 34 via the output circuit 33, Clogging detection alert information is visually displayed on the display 34 to prompt the operator to execute manual regeneration (step S6), and a value “1” requesting execution of manual regeneration is set in the state memory flag F. It memorizes the necessity of manual regeneration (step S7).

Next, the CPU 29 determines whether or not the combustion regeneration function start switch 25 is operated by the operator (step S8), but the manual regeneration process is not started unless the combustion regeneration function start switch 25 is actually operated. If the operator ignores the clogging detection alert display on the display 34, it is possible to carry out the processing of steps S16 to S20 related to the power shift in the same manner as described above.
In that case, the clogging detection alert display on the display 34 is maintained as it is.

At this stage, since the value “1” requesting execution of manual regeneration is already set in the state storage flag F, the processing from step S4 to step S7 is skipped in the processing after the next cycle.
However, since the process of step S2 required for carrying out the process related to the power shift is continuously executed, the power shift is performed in the same manner as described above unless the combustion regeneration function start switch 25 is actually operated. The related processing from step S16 to step 20 is allowed.

When the operation of the combustion regeneration function start switch 25 by the operator is detected in the power shift program of FIG. 3 that is repeatedly executed at predetermined intervals and the determination result in step S8 becomes true, the CPU 29 of the controller 11 outputs the output circuit 33. The operation command is output to the switching valves 23a and 23b, which are the second switching means, to shift the switching valve 23a to the left in FIG. 1 and to shift the switching valve 23b to the right in FIG. The switching valves 23a and 23b provided on the pressure transmission lines from the center bypass circuits 18a and 18b to the shuttle valves 21a and 21b, which are pilot pressure selection means, are closed together, and the negative from the center bypass circuits 18a and 18b. The control pressure is transmitted to the shuttle valves 21a and 21b which are pilot pressure selection means. Avoidance to.
Further, the CPU 29 outputs an operation command to the switching valves 22a and 22b as the first switching means via the output circuit 33 to operate the switching valves 22a and 22b, and the shuttle valves 21a and 21b as the pilot pressure selection means. Is forced to be in an operating state, so that the magnitude relationship between the pilot pressure for output selection supplied from the pilot pressure adjustment valve 10 and the pilot pressure for flow rate adjustment supplied from the center bypass circuits 18a and 18b is the shuttle valve. A comparatively high pilot pressure is supplied to the negative control controllers 7a and 7b as compared by 22a and 22b.
However, at this time, since the negative control pressure from the center bypass circuits 18a and 18b is no longer transmitted to the shuttle valves 21a and 21b, which are pilot pressure selection means, due to the closing of the switching valves 23a and 23b, the pilot in operation The pressure selection means, that is, the shuttle valves 21a and 21b, always select the pilot pressure for output selection supplied from the pilot pressure adjustment valve 10 as the high-pressure side pressure, and the negative control controllers 7a and 7b The pilot pressure for output selection supplied from the pressure adjustment valve 10 is input as the pilot pressure for flow rate adjustment.
Accordingly, the control valve group 5 which is a hydraulic system driven by the variable displacement pumps 3a and 3b is in a neutral state, that is, the negative control pressure which is feedback from the center bypass circuits 18a and 18b is high. Even under such circumstances, if the combustion regeneration function start switch 25 is operated, the pilot pressure for flow rate adjustment input to the negative control controllers 7a and 7b is supplied from the electromagnetic control type pilot pressure adjustment valve 10. When the combustion regeneration function start switch 25 is not operated, that is, when the negative control pressure from the center bypass circuits 18a and 18b is input to the negative control controllers 7a and 7b. Than negative control It is possible to reduce control unit 7a, a piston member 20a in 7b, the pump discharge amount of restrictions protrusion 20b.
As a result, the pump discharge amount of the variable displacement pumps 3a and 3b is increased, and the load of the diesel engine 2 that drives the variable displacement pumps 3a and 3b is increased. Particulate matter deposited on the diesel particulate filter 28 installed in the path can be removed by incineration.
At this time, the energy consumed by the operation of the variable displacement pumps 3a and 3b, that is, the product of the internal pressure acting on the center bypass circuits 18a and 18b and the pump discharge amount per unit time in the variable displacement pumps 3a and 3b. It is the load that acts on.
The upper limit of the internal pressure acting on the center bypass circuits 18a, 18b is determined by the setting of the relief valves 27a, 27b, and the pump discharge amount of the variable displacement pumps 3a, 3b is an output selection supplied from the electromagnetically controlled pilot pressure adjusting valve 10 Therefore, by controlling the pilot pressure regulating valve 10, a load suitable for incineration removal of particulate matter can be applied to the diesel engine 2. (End of step S9)

  The ECU 17 that has started the incineration and removal of the particulate matter deposited on the diesel particulate filter 28 in this way restarts the timer T and starts measuring the manual regeneration continuous execution time (step S10). Then, a value “2” indicating that the manual regeneration is being executed is set in the state storage flag F for storing the manual regeneration execution state and the like, and the fact that the manual regeneration process has been started is stored by itself (step S11).

Then, ECU 17 determines whether the time measured by the timer T has reached the set time T ₀ of the manual regeneration (step S12), the If not reached, and ends the series of processing in the present period.

At this stage, since the value “2” indicating that the manual regeneration is being executed is already set in the state storage flag F, the processing from step S2 to step S11 is skipped in the processing after the next cycle, and the ECU 17 determines that the determination result is constantly determining process in step S1 that is true, and, so that the time measured by the timer T is repeatedly executed only manual regeneration setting whether reaches the time T ₀ determination process (step S12).

Finally, when the time measured by the timer T reaches the manual regeneration set time T ₀ and the determination result in step S12 becomes true, the CPU 29 switches the first and second switching valves 23a and 23b to the first switching means. The switching valves 22a and 22b, which are the switching means, are returned to the non-operating state before the start of manual regeneration (step S13), the display of the clogging detection alert information on the display 34 is terminated (step S14), An initial value “0” indicating completion of manual regeneration is set in the state storage flag F, and the fact that manual regeneration is completed is stored by itself (step S15).
It is also possible to employ a configuration in which the switching valves 23a, 23b, 22a, and 22b are operated only for the operation continuation time of the combustion regeneration function start switch 25 by the operator, instead of the configuration in which the manual regeneration continuation time is controlled by a timer.

  Then, when the initial value “0” is set again in the state storage flag F, the execution of the processing of steps S16 to S20 related to the power shift is permitted again in the same manner as described above.

In this embodiment, the ECU 17 steadily determines the deviation of the exhaust pressure before and after the diesel particulate filter 24 detected by the differential pressure sensor 28, that is, the degree of clogging of the diesel particulate filter 24. Lookout, output from the CPU 29 when the exhaust pressure deviation before and after the diesel particulate filter 24 exceeds a preset threshold, that is, when the clogging of the diesel particulate filter 24 exceeds a certain limit Since an alert display signal is output to the display 34 via the circuit 33 and alert information for clogging detection is displayed on the display 34, the operator can use the display 34 installed around the instrument panel. When the combustion regeneration function start switch 25 should be operated simply by checking the display It is possible to properly grasp.
The exhaust pressure deviation value that should be regarded as occurrence of clogging varies depending on the engine accelerator command value, the engine speed, etc., but the ECU 17 stores a correspondence relationship between the engine accelerator command value, the engine speed, and the threshold value. The threshold value corresponding to the value of the engine accelerator command value and the engine speed at that time is specified with reference to, so that the presence or absence of clogging can be accurately determined (see paragraph 0039).

In addition, except for the switching valves 23a and 23b serving as the second switching means, there is no need to install special hardware for realizing manual regeneration (comparison with Japanese Patent No. 4667083). It is possible to provide the hydraulic control device 1 having the low cost.
As described above, the load acting on the diesel engine 2 is determined by the product of the internal pressure acting on the center bypass circuits 18a and 18b and the pump discharge amount per unit time in the variable displacement pumps 3a and 3b. The pump discharge amount of 3a and 3b can be freely adjusted by the pilot pressure for output selection supplied from the electromagnetic control type pilot pressure adjusting valve 10, so that the particles can be controlled only by controlling the pilot pressure adjusting valve 10. By applying a load suitable for incineration removal of particulate matter to the diesel engine 2, it is possible to carry out the incineration removal operation of particulate matter in an optimum state.
Since the driving current of the pilot pressure regulating valve 10 required for applying a load suitable for incineration removal of particulate matter to the diesel engine 2 can be easily obtained by experiment, the value of this driving current is stored in the ROM 30. In step S9, an appropriate drive current value is read from the ROM 30, and the drive current is applied to the pilot pressure adjusting valve 10. In step S17, the application of the drive current is canceled. Become.

[Second Embodiment]
FIG. 10 eliminates the second switching means constituted by the switching valves 23a and 23b, and always puts on the pressure transmission line from the shuttle valves 21a and 21b serving as pilot pressure selection means to the negative control control sections 7a and 7b. Open type second switching means, that is, switching valves 35a and 35b are provided, and the switching valves 35a and 35b, which are second switching means, are forcibly closed instead of the combustion regeneration function start switch 25 described above. FIG. 3 is a functional block diagram showing an outline of the configuration of a hydraulic control apparatus 1 ′ for a work vehicle provided with a combustion regeneration function start switch 25 ′.

  Since other configurations are the same as those of the hydraulic control device 1 according to the embodiment disclosed in FIGS. 1 and 2, the reference numerals corresponding to the respective parts are given in FIG. For the description of FIG. 3, the flowchart of the power shift program shown in FIG. 3 is used.

When such an arrangement is applied, when the operator operates the combustion regeneration function start switch 25 ′, the CPU of the controller 11 detects this operation (processing corresponding to step S8 in FIG. 3). An operation command is output to the switching valves 35a and 35b, which are the second switching means, via the output circuit to shift the switching valve 35a to the left in FIG. 10 and to move the switching valve 35b to the right in FIG. Shifting is performed to shut off the pressure transmission lines from the shuttle valves 21a and 21b serving as pilot pressure selection means to the negative control control sections 7a and 7b, and from the shuttle valves 21a and 21b serving as pilot pressure selection means to the negative control control section. Transmission of the pilot pressure for adjusting the flow rate to 7a and 7b is avoided (processing corresponding to step S9 in FIG. 3).
Accordingly, the control valve group 5 which is a hydraulic system driven by the variable displacement pumps 3a and 3b is in a neutral state, that is, the negative control pressure which is feedback from the center bypass circuits 18a and 18b is high. Even under such circumstances, if the combustion regeneration function start switch 25 ′ is operated, the pilot pressure for flow rate adjustment input to the negative control controllers 7a and 7b is maintained at the atmospheric pressure, When the combustion regeneration function start switch 25 'is not operated, that is, when the negative control pressure from the center bypass circuits 18a and 18b is input to the negative control controllers 7a and 7b, the piston members 20a in the negative control controllers 7a and 7b, Pump discharge by 20b protrusion Limit is reduced.
As a result, the pump discharge amount of the variable displacement pumps 3a and 3b increases, the load of the diesel engine 2 that drives the variable displacement pumps 3a and 3b increases, and the exhaust temperature of the diesel engine 2 rises. Particulate matter deposited on the diesel particulate filter 28 installed in the exhaust path can be incinerated and removed.
At this time, the energy consumed by the operation of the variable displacement pumps 3a and 3b, that is, the product of the internal pressure acting on the center bypass circuits 18a and 18b and the pump discharge amount per unit time in the variable displacement pumps 3a and 3b is the diesel engine. 2 is a load acting on 2.
Under this circumstance, the restriction of the pump discharge amount of the variable displacement pumps 3a, 3b by the negative control controllers 7a, 7b is completely released, so that the energy consumed by the operation of the variable displacement pumps 3a, 3b, that is, diesel The load acting on the engine 2 is the operation state of the power shift control units 6a and 6b at that time, that is, the operation of the power shift control units 7a and 7b controlled by the pilot pressure for output selection supplied from the pilot pressure adjusting valve 10. It becomes the maximum load in the pump control horsepower diagram according to the state.
In addition, the timing which returns the switching valves 35a and 35b which are the 2nd switching means to a non-operation initial state is a timing corresponding to step S17 of FIG.

  Also in this embodiment, except for the switching valves 35a and 35b serving as the second switching means, it is not necessary to newly install special hardware for realizing manual regeneration (comparison with Japanese Patent No. 4667083). It is possible to provide the hydraulic control device 1 ′ having a manual regeneration function at low cost.

  A part or all of the embodiment disclosed above can be appropriately expressed by the description shown in the following supplementary notes, but the form for carrying out the invention and the technical idea of the invention are not limited to these. Absent.

[Appendix 1]
A diesel particulate filter (24) for removing particulate matter in the exhaust path of the diesel engine (2);
The variable displacement pump is adjusted by adjusting the pump discharge amount of the variable displacement pump (3a, 3b) by following the change in pump discharge pressure of the variable displacement pump (3a, 3b) driven by the diesel engine (2). The output of the variable displacement pump is adjusted by holding the output of (3a, 3b) at the set value and adjusting the pump discharge amount of the variable displacement pump (3a, 3b) in response to the pilot pressure for output selection. Negative from the center bypass circuit (18a, 18b) of the hydraulic system (5) driven by the hydraulic fluid discharged from the power shift control unit (6a, 6b) and the variable displacement pump (3a, 3b) that changes Among the control pressure and the pilot pressure for output selection supplied from the electromagnetic control type pilot pressure adjustment valve (10), the pressure on the high pressure side is a pyrolyzer for adjusting the flow rate. Pilot pressure selection means (21a, 21b) to be selected as a candidate for the pressure, an operating state in which the pressure selected as a candidate by the pilot pressure selection means (21a, 21b) is output as a pilot pressure for flow rate adjustment, and the negative A first switching means (22a, 22b) for switching the operating state of the pilot pressure selecting means (21a, 21b) to any one of the non-operating states for outputting the control pressure as a pilot pressure for flow rate adjustment; and the pilot pressure selecting The pumps of the variable displacement pumps (3a, 3b) in a direction to decrease the pump discharge amount of the variable displacement pumps (3a, 3b) according to the increase in the pilot pressure for flow rate adjustment output from the means (21a, 21b) Work with negative control control part (7a, 7b) to adjust discharge amount In the vehicle hydraulic control unit (1),
A normally open second switching means (23a, 23a, 18b) arranged on the pressure transmission line from the center bypass circuit (18a, 18b) to the pilot pressure selection means (21a, 21b) to open and close the line. 23b)
Combustion regeneration that forcibly closes the second switching means (23a, 23b) and forcibly activates the pilot pressure selection means (21a, 21b) by the first switching means (22a, 22b) A hydraulic control apparatus (1) for a work vehicle, comprising a function start switch (25).

[Appendix 2]
A diesel particulate filter (24) for removing particulate matter in the exhaust path of the diesel engine (2);
The variable displacement pump is adjusted by adjusting the pump discharge amount of the variable displacement pump (3a, 3b) by following the change in pump discharge pressure of the variable displacement pump (3a, 3b) driven by the diesel engine (2). The variable displacement pumps (3a, 3b) are maintained by holding the output of (3a, 3b) at a set value and adjusting the pump discharge amount of the variable displacement pumps (3a, 3b) by receiving a pilot pressure for output selection. The power shift control unit (6a, 6b) for changing the set value of the output of the output and the center bypass circuit (18a, 6a) of the hydraulic system (5) driven by the hydraulic oil discharged from the variable displacement pump (3a, 3b) Among the negative control pressure from 18b) and the pilot pressure for output selection supplied from the electromagnetic control type pilot pressure regulating valve (10), the pressure on the high pressure side is flowed. Pilot pressure selection means (21a, 21b) for selecting as a pilot pressure candidate for adjustment, and an operating state for outputting the pressure selected as a candidate by the pilot pressure selection means (21a, 21b) as a pilot pressure for flow rate adjustment And a first switching means (22a, 22b) for switching the operating state of the pilot pressure selecting means to any one of the non-operating states for outputting the negative control pressure as a pilot pressure for flow rate adjustment, and the pilot pressure selecting means ( The pump discharge amount of the variable displacement pump (3a, 3b) in a direction to decrease the pump discharge amount of the variable displacement pump (3a, 3b) in accordance with the increase of the pilot pressure for flow rate adjustment output from 21a, 21b) Negative control control section (7a, 7b) for adjusting the above-mentioned variable capacitance The pressure sensor (26a, 26b) for detecting the pump discharge pressure of the pump (3a, 3b) and the power shift control unit (6a, 6b) are shifted to the low output side beyond the normal power shift control range. In order to satisfy the pump discharge pressure of the variable displacement pump (3a, 3b) and the pump discharge amount corresponding to the pump discharge pressure as a function representing the relationship between the pump discharge pressure and the pump discharge amount, the negative control control unit Non-volatile storage means (30) storing the relationship with the pilot pressure for flow rate adjustment required by (7a, 7b), and the engine speed in the low speed range where the torque output of the diesel engine (2) decreases. compared set threshold and (R _S) the current values of engine speed and (R _n) based on the current value of the engine rotational speed (R _n) is the threshold value (R ) If less than the first switching means (22a, while the pilot pressure selecting means (21a, 21b) and a non-operating state by 22b), the current value of the engine rotational speed _{(R n)} is the threshold value (R _{When the} pressure falls below _{S 2} ), the pilot pressure selection means (21a, 21b) is activated by the first switching means (22a, 22b) and is based on the pump discharge pressure detected by the pressure sensor (26a, 26b). The flow rate adjustment pilot pressure is obtained from the nonvolatile storage means (30), and the pilot pressure adjustment valve (10) is controlled so that the obtained flow rate adjustment pilot pressure is output. In a hydraulic control device (1) for a work vehicle provided with
A normally open second switching means (23a, 23a, 18b) arranged on the pressure transmission line from the center bypass circuit (18a, 18b) to the pilot pressure selection means (21a, 21b) to open and close the line. 23b)
Combustion regeneration that forcibly closes the second switching means (23a, 23b) and forcibly activates the pilot pressure selection means (21a, 21b) by the first switching means (22a, 22b) A hydraulic control apparatus (1) for a work vehicle, comprising a function start switch (25).

When such a configuration is applied, the low speed rotation in which the torque output of the diesel engine (2) that drives the variable displacement pump (3a, 3b) is reduced while the combustion regeneration function start switch (25) is inactive. In a situation where the current value (R _n ) of the engine speed does not fall below the threshold value (R _S ) set based on the engine speed in the region, the pilot pressure selection means (22a, 22b) 21a, 21b) is switched to the non-operating state, and the pilot pressure for output selection supplied from the electromagnetically controlled pilot pressure regulating valve (10) is supplied to the power shift control unit (6a, 6b), as in the conventional case. Thus, normal power shift control is performed.
On the other hand, the engine speed in the low rotation range where the torque output of the diesel engine (2) that drives the variable displacement pumps (3a, 3b) is reduced when the combustion regeneration function start switch (25) is inactive. The pilot pressure selection means (21a, 21b) is activated by the first switching means (22a, 22b) under the situation _where the current value (R _n ) of the engine speed is below the threshold value (R _S ) set based on Is switched to the state, and the negative control pressure (7a, 7b) is selected by selecting the high pressure side pressure from the negative control pressure from the center bypass circuit (18a, 18b) of the hydraulic system (5) and the pilot pressure for output selection. Is supplied as a pilot pressure for flow rate adjustment.
Under the situation where the current value (R _n ) of the engine speed is lower than the threshold value (R _S ), the pilot pressure for output selection supplied from the pilot pressure regulating valve (10) inevitably becomes high, and as a result, The negative control pressure from the center bypass circuit (18a, 18b) of the hydraulic system (5) is exceeded, and the pilot pressure selection means (21a, 21b) supplies the pilot pressure for output selection to the negative control control unit (7a, 7b). ) As a pilot pressure for adjusting the flow rate.
As described above, when the pilot pressure selection means (21a, 21b) is in the operating state, the control means (29) detects the pump discharge pressure instead of the normal pilot pressure for output selection. Based on the pressure detected by the sensors (26a, 26b), the pilot pressure for flow rate adjustment is obtained from the non-volatile storage means (30), and the pilot pressure supplied from the pilot pressure adjustment valve (10) is non-volatile. The pilot pressure adjusting valve (10) is controlled so that the flow rate adjusting pilot pressure obtained from the storage means (30) is obtained. Then, this pilot pressure is supplied from the pilot pressure adjusting valve (10) to the negative control controller (7a, 7b) via the pilot pressure selection means (21a, 21b).
The nonvolatile storage means (30) has a function representing the relationship between a desired pump discharge pressure and pump discharge amount, specifically, a range of normal power shift control using the power shift control units (6a, 6b). For the flow rate adjustment required by the negative control controller to satisfy the pump discharge pressure and the pump discharge amount corresponding to the pump discharge pressure so that the relationship between the pump discharge pressure shifted to the low output side and the pump discharge amount The pilot pressure for flow rate adjustment corresponding to the current value of the pump discharge pressure detected by the pressure sensors (26a, 26b) is obtained from the nonvolatile storage means (30). Normal power shift using only the power shift control unit (6a, 6b) by supplying to the negative control control unit (7a, 7b) It is possible to realize a power shift beyond the control of the range.
For this reason, the range of the power shift of the variable displacement pumps (3a, 3b) is expanded to a region where the torque output of the diesel engine (2) for driving the variable displacement pumps (3a, 3b) is reduced, that is, the low output side. It becomes possible.
And when carrying out the incineration removal of a particulate matter compulsorily, when an operator operates a combustion regeneration function start switch (25), pilot pressure selection means (21a, 18b) from a center bypass circuit (18a, 18b). 21b) closes the normally open type second switching means (23a, 23b) provided on the pressure transmission line, and the negative control pressure from the center bypass circuit (18a, 18b) becomes the pilot pressure selection means. The pilot pressure selection means (21a, 21b) is forcibly brought into an operating state by the first switching means (22a, 22b) while avoiding transmission to (21a, 21b).
As a result of the negative control pressure from the center bypass circuit (18a, 18b) not being transmitted to the pilot pressure selection means (21a, 21b), the pilot pressure selection means (21a, 21b) in the operating state is subjected to electromagnetic control type pilot pressure. The pilot pressure for output selection supplied from the regulating valve (10) is selected as the high-pressure side pressure, and the negative control controller (7a, 7b) is supplied from the electromagnetically controlled pilot pressure regulating valve (10). A pilot pressure for output selection is input as a pilot pressure for flow rate adjustment.
Therefore, the control valve of the hydraulic system (5) driven by the variable displacement pump (3a, 3b) is in a neutral state, that is, under the situation where the negative control pressure of the hydraulic system (5) is increased. However, the pilot pressure for flow rate adjustment input to the negative control controller (7a, 7b) can be lowered to the pilot pressure for output selection supplied from the electromagnetic control type pilot pressure adjustment valve (10). .
Therefore, when the combustion regeneration function start switch (25) is not operated, that is, when the negative control pressure of the hydraulic system (5) is input to the negative control control unit (7a, 7b), the variable displacement pump (3a, 3b) Since the pump discharge amount increases and the load on the diesel engine (2) that drives the variable displacement pumps (3a, 3b) increases, the exhaust path of the diesel engine (2) increases due to the rise in the exhaust temperature of the diesel engine (2). The particulate matter deposited on the diesel particulate filter (24) installed inside can be incinerated and removed.
At this time, the energy consumed by the operation of the variable displacement pump (3a, 3b), that is, the internal pressure of the center bypass circuit (18a, 18b) of the hydraulic system (5) and the unit time in the variable displacement pump (3a, 3b). The product of the pump discharge amount is a load acting on the diesel engine (2).
Since the pump discharge amount is specified by the pilot pressure for output selection supplied from the electromagnetic control type pilot pressure adjusting valve (10), it is possible to control the particles by controlling the electromagnetic control type pilot pressure adjusting valve (10). A load suitable for incineration removal of the particulate matter can be applied to the diesel engine (2).
Since the driving current of the pilot pressure regulating valve (10) required for applying a load suitable for incineration removal of particulate matter to the diesel engine (2) can be easily obtained by experiment, the value of this driving current is Stored in the non-volatile storage means (30), close the second switching means (23a, 23b) and force the pilot pressure selection means (21a, 21b) with the first switching means (22a, 22b) When the operation state is activated, an appropriate drive current value is read from the non-volatile storage means (30) and the drive current is applied to the pilot pressure adjusting valve.

[Appendix 3]
Instead of the second switching means (23a, 23b), the pipe is opened and closed on a pressure transmission line from the pilot pressure selection means (21a, 21b) to the negative control control section (7a, 7b). While providing a normally open second switching means (35a, 35b),
Supplementary note 1 or Supplementary note characterized in that a combustion regeneration function start switch (25 ') for forcibly closing the second switching means (35a, 35b) is provided instead of the combustion regeneration function start switch (25). The work vehicle hydraulic control device (1 ′) according to claim 1.

  INDUSTRIAL APPLICABILITY The present invention can be generally used for a work vehicle including a crane vehicle, a power shovel, and the like, and a variable displacement pump driven by a diesel engine having a diesel particulate filter in an exhaust path.

1, 1 'Hydraulic control device for work vehicle 2 Diesel engines 3a, 3b Variable displacement pump 4 Control pump 5 Control valve group (hydraulic system)
6a, 6b Power shift control units 7a, 7b Negative control control units 8a, 8b Tilt plates 9a, 9b Adjusting means 10 Pilot pressure adjusting valve 11 Controllers 12a, 12b Piston members 13a, 13b Control valves 14a, 14b Oil chambers 15a, 15b Oil chamber 16a, 16b Piston member 17 Engine control unit (ECU)
18a, 18b Center bypass circuits 19a, 19b Throttle valves 20a, 20b Piston members 21a, 21b Shuttle valves (pilot pressure selection means)
22a, 22b switching valve (first switching means)
23a, 23b switching valve (second switching means)
24 Diesel particulate filter (DPF)
25, 25 'Combustion regeneration function start switch 26a, 26b Pressure sensor 27a, 27b Relief valve 28 Differential pressure sensor 29 Microprocessor (CPU)
30 ROM
31 RAM
32 Input circuit 33 Output circuit 34 Display (DSP)
35a, 35b switching valve (second switching means)

Claims (2)

Having a diesel particulate filter to remove particulate matter in the exhaust path of the diesel engine,
By adjusting the pump discharge amount of the variable displacement pump by following the change in the pump discharge pressure of the variable displacement pump driven by the diesel engine, the output of the variable displacement pump is maintained at a set value and for output selection. Driven by hydraulic power discharged from the variable displacement pump and a power shift control unit that changes the set value of the output of the variable displacement pump by adjusting the pump discharge amount of the variable displacement pump in response to pilot pressure A pilot pressure that selects a high-pressure side pressure as a pilot pressure candidate for flow rate adjustment from the negative control pressure from the center bypass circuit of the hydraulic system and the pilot pressure for output selection supplied from the electromagnetic control type pilot pressure adjustment valve The pressure selected as a candidate by the selection means and the pilot pressure selection means is adjusted in flow rate. A first switching means for switching the operating state of the pilot pressure selecting means to either an operating state for outputting the pilot pressure as a pilot pressure or a non-operating state for outputting the negative control pressure as a pilot pressure for flow rate adjustment, and the pilot pressure An operation including a negative control control unit for adjusting the pump discharge amount of the variable displacement pump in a direction to decrease the pump discharge amount of the variable displacement pump in accordance with an increase in the pilot pressure for flow rate adjustment output from the selection means In the hydraulic control device for cars,
A normally-opening type second switching means arranged on the pressure transmission line from the center bypass circuit to the pilot pressure selection means to open and close the line;
And a combustion regeneration function start switch for forcibly closing the second switching means and forcibly operating the pilot pressure selection means by the first switching means. Hydraulic control device. In place of the second switching means, provided with a normally open type second switching means for opening and closing the pipeline on the pressure transmission pipeline from the pilot pressure selection means to the negative control control unit,
2. The hydraulic control device for a work vehicle according to claim 1, wherein a combustion regeneration function start switch for forcibly closing the second switching means is provided instead of the combustion regeneration function start switch.

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