JP5075845B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle in which a traveling machine body supports a traveling device via a suspension mechanism.

The work vehicle described above is capable of traveling while absorbing the unevenness of the traveling place by the operation of the suspension mechanism.
Conventionally, there has been a tractor described in Patent Document 1 as this type of work vehicle. The tractor described in Patent Document 1 includes a suspension system having cylinders 16 and 17 that act on the front wheel 14. (Each symbol is described in the publication.)

USP 6145859

  Due to the fact that the work area where the work vehicle travels is more uneven than the paved road and that the work vehicle is often equipped with a work device such as a loader or plow, it is caused by work surface unevenness and work device load. Then, the suspension mechanism operates, and the operation of the suspension mechanism easily exceeds the target range and is displaced to the aircraft ascending side or the aircraft descending side.

If the operation of the suspension mechanism is displaced beyond the target range, the ground height of the work equipment will change drastically due to the change in the ground height of the traveling aircraft, which makes it difficult to work. Even if the suspension mechanism is provided, operation change means for changing the operation of the suspension mechanism to the ascending side and the descending side of the body may be provided so that the change in the height of the traveling body with respect to the ground can be suppressed and the work can be advantageously performed. .
In other words, when the suspension mechanism operation is displaced from the target range to the aircraft ascending side and the aircraft descending side due to the load of the work equipment, etc., the suspension mechanism is operated so that the ground height of the traveling aircraft is in a predetermined height range as much as possible. It may be configured to move to the target range side.

  In a work vehicle, the operation of the suspension mechanism is likely to occur frequently. Therefore, if the operation changing means accompanying the operation of the suspension mechanism is also frequently operated, a problem in terms of durability of the operation changing means occurs.

  An object of the present invention is to provide a work vehicle that can maintain a ground height of a traveling machine body at a predetermined height while having a suspension mechanism, and that is excellent in durability and responsiveness. is there.

The first aspect of the present invention is a work vehicle in which a traveling machine body supports a traveling device via a suspension mechanism.
Lifting detection means for detecting the lifting displacement of the operation of the suspension mechanism;
An operation changing means capable of changing the operation of the suspension mechanism to the airframe rising side and the airframe lowering side;
Control means for operating the operation changing means so that the operation of the suspension mechanism moves to the target range side based on the detection information by the lifting detection means,
Comprising stop state detecting means for detecting an operation stop state of the suspension mechanism;
When the suspension mechanism is in an operation stop state, the operation change means is prioritized over the detection information by the lift detection means so that the operation of the suspension mechanism moves to the target range side based on the detection information by the stop state detection means. Auxiliary control means to be operated is provided.

  According to the first aspect of the present invention, when the operation of the suspension mechanism occurs, the control means operates the operation changing means to operate, and the operation changing means moves the operation of the suspension mechanism to the target range side. Regardless of the occurrence of the operation displacement, the ground height of the traveling machine body can be adjusted to be within a predetermined height range.

When work devices such as loaders and plows are connected and the work device is raised to the non-working state, the entire load of the work device is applied to the traveling machine body, and when the work device is lowered to the lowered work state, the work device is Since the ground is supported, the load applied to the traveling machine body is reduced. In particular, when the load is raked by the loader, a heavy load is applied to the traveling machine due to the weight of the rake, and when the load is released by the loader, the large load that has been applied to the machine by the rake. There is no load.
In other words, if the suspension mechanism is actuated by a small load such as unevenness on the ground, it will be displaced back to the aircraft lowering side after being displaced to the aircraft ascending side, or returned to the aircraft ascending side after being displaced to the aircraft descending side. It will be displaced. On the other hand, when the work device is operated, a large load applied to the traveling machine body is generated or lost depending on the handling object of the work device, so that the operation of the suspension mechanism is greatly increased on the aircraft ascending side or the aircraft descending side. There may be displacement and no return-side displacement or a little return-side displacement. In other words, when the operation of the suspension mechanism is displaced to the airframe ascending side or the airframe descending side, it remains displaced to the airframe ascending side or the airframe descending side. A certain operation stop state occurs in the suspension mechanism.

  In this case, according to the configuration of the first aspect of the present invention, the suspension state of the suspension mechanism is detected by the stop state detection means, and the auxiliary control means prioritizes the operation change means over the detection information by the lift detection means based on this detection information. The operation changing means is operated to move the operation of the suspension mechanism to the target range side. As a result, when a large operating displacement of the suspension mechanism due to the connection of the working device or the work by the working device occurs, an operation for quickly responding to this and moving the operation of the suspension mechanism to the target range is performed. It is possible to quickly adjust the height to the ground so that it falls within a predetermined height range.

Therefore, the suspension mechanism operates to absorb the unevenness of the traveling place and can travel comfortably, but the grounding height of the traveling machine body and the working apparatus can be increased regardless of whether the working device is connected or the working device is connected. It is possible to work at a predetermined height or a substantially predetermined height with good workability.
In addition, when the suspension mechanism does not stop due to an operation displacement caused by a small load, the operation change means is operated by the control means based on the detection information from the lift detection means, thereby changing the operation. It is possible to make the operation change means less likely to be deteriorated by making the operation frequency of the means relatively low, and to make the operation change means have excellent durability.
When the load due to the weight of the work device or the work handled by the work device is applied or the load due to the work handled by the work device is lost, the operation change means is based on the detection information by the stop state detection means by the auxiliary control means, By operating in preference to the detection information from the lift detection means, the suspension mechanism can be operated quickly by responding quickly to the displacement of the suspension mechanism due to the load caused by the weight of the work device and the weight of the work handled by the work device. By moving to the range side, the traveling machine body and the work device can be quickly adjusted to an appropriate ground height or a height close thereto, and work can be performed with good workability.

The second aspect of the present invention is a work vehicle in which a traveling machine body supports a traveling device via a suspension mechanism.
An operation changing means capable of changing the operation of the suspension mechanism to the airframe rising side and the airframe lowering side;
Intermediate position detecting means for detecting a maximum position and a minimum position of operation of the suspension mechanism and detecting an intermediate position between the maximum and minimum positions;
Integrating means for integrating the number of times the intermediate position deviates from the target range;
Control means for operating the operation changing means so that the intermediate position moves to the target range side when the number of times of integration by the integration means exceeds the set number of times of integration,
Comprising stop state detecting means for detecting an operation stop state of the suspension mechanism;
When the suspension mechanism is in an operation stop state, the operation change means is prioritized over the number of integrations by the integration means so that the operation of the suspension mechanism moves to the target range side based on the detection information by the stop state detection means. Auxiliary control means for operating is provided.

  According to the configuration of the second aspect of the invention, even if the suspension mechanism is operated and the operation of the suspension mechanism is displaced from the target range, the operation changing means does not always operate immediately.

In other words, if the suspension mechanism operation occurs due to a small load, the operation may be displaced to the aircraft ascending side after being displaced to the aircraft ascending side, or may be displaced to the aircraft ascending side after being displaced to the aircraft descending side. Since the maximum and minimum positions occur in the operation of the suspension mechanism, the maximum and minimum positions of the suspension mechanism are detected, the intermediate position between the maximum and minimum positions is detected, and the intermediate position and the target range are determined. The number of times that the intermediate position has been deviated from the target range is integrated, and when the number of integration exceeds the set integration number, the operation changing means operates so that the intermediate position moves toward the target range. Therefore, even if the operation of the suspension mechanism is displaced from the target range to the airframe ascending side and the airframe descending side, and the intermediate position is displaced from the target range to the airframe ascending side and the airframe descending side, the intermediate position is not within the target range. The operation changing means does not operate unless the set number of times exceeds the set integration number.
In short, the number of times the intermediate position deviates from the target range even if the operation of the suspension mechanism deviates from the target range to the airframe ascending side and airframe descending side, and the intermediate position deviates from the target range to the airframe ascending side and airframe descending side. If the value does not exceed the set number of integrations, the traveling aircraft is considered to be within the predetermined height range during the set time for integration, and the operation change means is not operated and the operation is changed each time the suspension mechanism is activated. Compared with the case where the means is configured to operate, it is possible to reduce the operation frequency of the operation changing means and to prevent the operation changing means from being deteriorated.

When work devices such as loaders and plows are connected and the work device is raised to the non-working state, the entire load of the work device is applied to the traveling machine body, and when the work device is lowered to the lowered work state, the work device is Since the ground is supported, the load applied to the traveling machine body is reduced. In particular, when the load is raked by the loader, a heavy load is applied to the traveling machine due to the weight of the rake, and when the load is released by the loader, the large load that has been applied to the machine by the rake. There is no load.
In other words, if the suspension mechanism is actuated by a small load such as unevenness on the ground, it will be displaced back to the airframe descending side after being displaced to the airframe ascending side, or returned to the airframe ascending side after being displaced to the airframe descending side. It will be displaced. On the other hand, when the work device is operated, a large load applied to the traveling machine body is generated or lost depending on the handling object of the work device, so that the operation of the suspension mechanism is greatly increased on the aircraft ascending side or the aircraft descending side. There may be displacement and no return-side displacement or a little return-side displacement. That is, when the operation of the suspension mechanism is displaced to the airframe ascending side or the airframe descending side, it remains displaced to the airframe ascending side or the airframe descending side, and there is no subsequent return side displacement or the return side displacement is slight. A certain operation stop state occurs in the suspension mechanism.

  In this case, according to the configuration of the second aspect of the invention, the suspension state of the suspension mechanism is detected by the stop state detection means, and the auxiliary control means prioritizes the operation change means by the integration means based on the detection result. Manipulate. As a result, when a large operating displacement of the suspension mechanism due to the connection of the working device or the work by the working device occurs, an operation for quickly responding to this and moving the operation of the suspension mechanism to the target range is performed. It is possible to quickly adjust the height to the ground so that it falls within a predetermined height range.

Therefore, the suspension mechanism operates to absorb the unevenness of the traveling place and can travel comfortably, but the grounding height of the traveling machine body and the working apparatus can be increased regardless of whether the working device is connected or the working device is connected. It is possible to work at a predetermined height or a substantially predetermined height with good workability.
In addition, when the suspension mechanism does not stop due to an operation displacement due to unevenness of the ground, the operation change means is operated by the control means based on the set number of integrations, so that the operation change means The operation frequency can be made relatively low to make it difficult for the operation changing means to deteriorate, and the operation changing means can have excellent durability.
When the load due to the weight of the work device or the handling part by the work device is applied, or when the load due to the work handled by the work device is lost, the operation change means is based on the detection information by the stop state detection means by the auxiliary control means, By operating in preference to the set number of times, the suspension mechanism can be quickly moved to the target range by quickly responding to the displacement of the suspension mechanism due to the load due to the weight of the work equipment and the weight of the work equipment. It is possible to move and quickly adjust the traveling machine body and the working device to an appropriate ground height or a height close thereto to work in a state with good workability.

It is a side view which shows the whole tractor. It is a side view which shows a front-wheel support part. It is a hydraulic circuit diagram. It is a perspective view which shows a support bracket. It is explanatory drawing which shows the working displacement of a hydraulic cylinder. It is a block diagram of a suspension control device. It is a flowchart of the first half of control of a hydraulic cylinder. It is a flowchart of the latter half of control of a hydraulic cylinder. (A) is explanatory drawing which shows the operating displacement of a hydraulic cylinder. (B) is explanatory drawing which shows the operating speed change of a hydraulic cylinder.

Embodiments of the present invention will be described below with reference to the drawings.
[1]
As shown in FIG. 1, a tractor, which is an example of a work vehicle, includes a pair of left and right front wheels 1 and 1 and a pair of left and right rear wheels 2 and 2.

As shown in FIG. 1, a tractor traveling machine body 5 includes an engine 4, a transmission case 3 connected to a rear portion of the engine 4, and a front wheel support frame 5 a connected to a lower portion of the engine 4 for supporting front wheels. It is. The traveling machine body 5 includes a lift arm 3 a that is mounted on both lateral sides of the rear portion of the transmission case 3 so as to be swingable up and down. The right and left rear wheels 2 are not supported by the transmission case 3 at the rear of the fuselage via a suspension mechanism, but are supported in a fixed position.
This tractor is configured such that a plow (not shown) is connected to a rear portion of the traveling machine body 5 via a lift arm 3a so that the plow (not shown) can be lifted up and down freely to constitute a riding type tiller. Various working devices are connected to the rear part of the machine body 5 so as to be movable up and down to form various riding type work machines. Further, this tractor is connected to a front portion of the traveling machine body 5 so that a front loader (not shown) can be moved up and down, thereby constituting a riding type loader.

As shown in FIGS. 1, 2, and 4, a support bracket 6 having a U-shape when viewed from the side is supported so as to be swingable up and down around a horizontal axis P1 at the rear of the front wheel support frame 5a. Two hydraulic cylinders 7 and 7 (corresponding to a suspension mechanism) are connected across the front portion and the front portion of the support bracket 6. A front axle case 8 is supported in a freely rolling manner around the front and rear axis P2 of the support bracket 6, and the right and left front wheels 1 are supported on the right and left sides of the front axle case 8.
That is, the traveling machine body 5 supports the pair of left and right front wheels 1 and 1 via the two hydraulic cylinders 7 and 7 in the support frame 5a.

[2]
Next, the hydraulic circuit of the hydraulic cylinder 7 will be described.
As shown in FIG. 3, the hydraulic cylinder 7 is configured as a double-acting type having an oil chamber 7a on the bottom side and an oil chamber 7b on the piston side. A gas-filled accumulator 11, a pair of pilot operated check valves 13, and a relief valve 15 for protecting the hydraulic circuit are connected to an oil passage 9 connected to an oil chamber 7a of the hydraulic cylinder 7. A pilot-operated switching valve 17 having three types of orifices of “large”, “medium”, and “small” is provided in front of the accumulator 11, and a pilot valve 20 for operating the switching valve 17 is provided. Yes. A gas-filled accumulator 12, a pair of pilot operated check valves 14 and a relief valve 16 for protecting the hydraulic circuit are connected to an oil passage 10 connected to the oil chamber 7b of the hydraulic cylinder 7.

  As shown in FIG. 3, the check valves 13 and 14 are provided with a pilot valve 19 for supplying and discharging pilot hydraulic oil, and the check valves 13 and 14 are shut off by the pilot valve 19 (accumulators 11 and 12 and And the open state (accumulators 11 and 12 to the oil chambers 7a and 7b of the hydraulic cylinder 7, and the accumulator 11 from the oil chambers 7a and 7b of the hydraulic cylinder 7). , 12 to allow the flow of both hydraulic fluids to.

  As shown in FIG. 3, the hydraulic oil of the pump 30 is supplied to the control valve 18 (corresponding to the operation changing means) via the filter 31, the diversion valve 32 and the check valve 33, and the diversion valve 32 and the check valve A relief valve 34 is connected between the first and second members 33. An oil passage 21 is connected across the portion between the oil chamber 7a of the hydraulic cylinder 7 and the check valve 13 in the oil passage 9 and the control valve 18, and is opposite to the oil chamber 7b of the hydraulic cylinder 7 in the oil passage 10. An oil passage 22 is connected across the portion between the stop valve 14 and the control valve 18.

  As shown in FIG. 3, the control valve 18 supplies the operating oil to the oil passage 21 (the oil chamber 7 b of the hydraulic cylinder 7) and the oil passage 22 (the oil chamber 7 b of the hydraulic cylinder 7). A three-position switching type, that is, a lowered position 18D to be supplied and a neutral position 18N, is configured as a pilot operated type, and is provided with a pilot valve 29 for operating the control valve 18.

As shown in FIG. 3, a pilot operated check valve 23 and a throttle portion 25 are provided in the oil passage 21. The oil passage 22 is provided with a pilot operated check valve 24, a check valve 26 (the check valve 24 is on the oil passage 10 side and the check valve 26 is on the control valve 18 side), and a throttle portion 27. A relief valve 28 is connected between the stop valve 24 and the check valve 26 (throttle portion 27).
The pilot valves 19, 20, and 29 are electromagnetically operated. As described in [3], [4], and [5], which will be described later, the pilot valve 19, the pilot valve 20, 29 is operated, and the check valves 13 and 14, the control valve 18 and the switching valve 17 are operated.

[3]
Next, the operation of the hydraulic cylinder 7 will be described.
When the control valve 18 is operated to the neutral position 18N and the check valves 13 and 14 are operated in the open state as shown in FIG. 3 according to the structure described in the preceding item [2], When the front axle case 8 and the support bracket 6 try to swing up and down around the horizontal axis P1, the hydraulic cylinder 7 expands and contracts and operates between the oil chambers 7a, 7b of the hydraulic cylinder 7 and the accumulators 11, 12. The oil reciprocates, and the hydraulic cylinder 7 operates as a suspension mechanism having a spring constant K1.

In this case, the pressure in the oil chamber 7b and the oil passage 10 of the hydraulic cylinder 7 is maintained at the set pressure MP1 by the relief valve 28. The pressure of the oil chamber 7a of the hydraulic cylinder 7 is PH, the pressure receiving area of the piston of the oil chamber 7a of the hydraulic cylinder 7 is AH, and the pressure receiving area of the piston of the oil chamber 7b of the hydraulic cylinder 7 is AR (for the piston rod, AR is AH If the weight applied to the front part of the airframe (the weight applied to the hydraulic cylinder 7) is M and the gravitational acceleration is g, the following equation (1) is established.
Formula (1) M * g = PH * AH-MP1 * AR

  Accordingly, the pressure MP1 of the oil chamber 7b of the hydraulic cylinder 7, the pressure receiving area AH of the piston of the oil chamber 7a of the hydraulic cylinder 7, and the pressure receiving area AR of the piston of the oil chamber 7b of the hydraulic cylinder 7 are constant. The pressure PH of the oil chamber 7a is higher than the pressure MP1 of the oil chamber 7b of the hydraulic cylinder 7, and varies depending on the weight (weight applied to the hydraulic cylinder 7) M applied to the front of the machine body.

  The spring constant K1 of the hydraulic cylinder 7 is determined by the pressures PH and MP1 of the oil chambers 7a and 7b of the hydraulic cylinder 7, and increases as the pressure PH of the oil chamber 7a of the hydraulic cylinder 7 increases. The pressure PH of the oil chamber 7a of the hydraulic cylinder 7 decreases as the pressure PH decreases. Therefore, the spring constant K1 of the hydraulic cylinder 7 is determined by the weight (weight applied to the hydraulic cylinder 7) M applied to the front portion of the airframe, and the weight applied to the front portion of the airframe (weight applied to the hydraulic cylinder 7) M is large. As it becomes larger, the weight applied to the front part of the airframe (weight applied to the hydraulic cylinder 7) M becomes smaller.

  As shown in FIG. 3, when the control valve 18 is operated to the raised position 18U and the check valves 13 and 14 are operated to be shut off, hydraulic fluid is supplied from the control valve 18 to the oil chamber 7a of the hydraulic cylinder 7. The hydraulic oil is discharged from the oil chamber 7 b of the hydraulic cylinder 7 through the check valve 24 (operated to be opened by the pilot pressure) and the relief valve 28. In this case, the pressure in the oil chamber 7b and the oil passage 10 of the hydraulic cylinder 7 is maintained at the set pressure MP1 by the relief valve 28.

  As a result, the hydraulic cylinder 7 extends and the front part of the airframe rises (corresponding to a state in which the operation of the hydraulic cylinder 7 that is a suspension mechanism is changed to the airframe ascending side). Thereafter, when the control valve 18 is operated to the neutral position 18N and the check valves 13 and 14 are operated to the open state, the hydraulic cylinder 7 operates as the suspension mechanism with the hydraulic cylinder 7 extended as described above. To do.

  As shown in FIG. 3, when the control valve 18 is operated to the lowered position 18 </ b> D and the check valves 13, 14 are operated to shut off, the hydraulic oil is supplied from the control valve 18 to the oil chamber 7 b of the hydraulic cylinder 7. The hydraulic oil is discharged from the oil chamber 7 a of the hydraulic cylinder 7 through the check valve 23 (operated to be opened by the pilot pressure), the throttle portion 25, and the control valve 18. In this case, the pressure in the oil chamber 7b and the oil passage 10 of the hydraulic cylinder 7 is maintained at the set pressure MP1 by the relief valve 28.

  As a result, the hydraulic cylinder 7 is contracted and the front part of the airframe is lowered (corresponding to a state where the operation of the hydraulic cylinder 7 which is a suspension mechanism is changed to the airframe lowering side). Thereafter, when the control valve 18 is operated to the neutral position 18N and the check valves 13 and 14 are opened, the hydraulic cylinder 7 operates as a suspension mechanism with the hydraulic cylinder 7 contracted as described above. To do.

  As shown in FIGS. 3 and 6, a pressure sensor 36 for detecting the pressure in the oil chamber 7 a of the hydraulic cylinder 7 is provided, and a detection value of the pressure sensor 36 is input to the control device 35. Based on the detected value, a weight (weight applied to the hydraulic cylinder 7) M applied to the front portion of the machine body is calculated.

  As a result, when the weight applied to the front part of the machine body (weight applied to the hydraulic cylinder 7) M is increased by the connected working device (for example, the soil is picked up (loaded) by the front loader, the load is stacked. In this state, when the plow is lowered to the lowering work state and the plow is supported by grounding), the spring constant K1 of the hydraulic cylinder 7 is increased, and accordingly, the switching valve 17 is moved to the throttle side (the orifice having a small diameter). The damping force of the hydraulic cylinder 7 is increased.

  When the weight applied to the front part of the machine body (weight applied to the hydraulic cylinder 7) M is reduced by the connected working device (for example, the state where the sand load is discharged by the front loader, the state where the load is unloaded, the plow, ), The spring constant K1 of the hydraulic cylinder 7 is reduced, and accordingly, the switching valve 17 is on the throttle side (with a large diameter). The damping force of the hydraulic cylinder 7 is reduced by being operated to the orifice side.

[4]
FIG. 6 is a block diagram of a suspension control device that operates the hydraulic cylinder 7. As shown in this figure, the suspension control device includes a control device 35 linked to the pilot valves 19, 20, and 29, and includes a pressure sensor 36 and an operating position sensor 37 linked to the control device 35.

  The control device 35 is configured by using a microcomputer, and includes a control unit 40, an elevation detection unit 41, an intermediate position detection unit 42, an integration unit 43, an integration number setting unit 44, an auxiliary control unit 45, and a target setting unit 46. The stop state detecting means 38 is provided.

Next, the first half of the control of the hydraulic cylinder 7 will be described with reference to FIGS.
The operation position sensor 37 detects the operation position (extension / contraction position) of the hydraulic cylinder 7. The detection value of the operation position sensor 37 is input to the control device 35, and the operation position (expanded position) of the hydraulic cylinder 7 is stored in the control device 35.

  The raising / lowering detecting means 41 is based on the detection information of the operating position sensor 37 and the central position of the operation of the hydraulic cylinder 7 set by the target setting means 46 (see FIG. 5). Detects vertical displacement. In this case, the telescopic operating position sensor 37 is directly attached to the hydraulic cylinder 7 to detect the operating position (extensible position) of the hydraulic cylinder 7. Alternatively, a rotary type operation position sensor 37 is attached to the position of the horizontal axis P1 shown in FIG. 2, and the angle of the support bracket 6 with respect to the support frame 5 is detected as the operation position (extension / contraction position) of the hydraulic cylinder 7.

  As shown in FIG. 5, when the operation position (extension / contraction position) of the hydraulic cylinder 7 is the center position, the airframe is substantially parallel (substantially horizontal) to the ground. A target range H1 having a certain range on the aircraft ascending side and the aircraft descending side with respect to the center position is set by the target setting means 46.

  The number N of integrations is set by the control device 35. First, the integration number N is set to “0” (step S2). In a state where the control valve 18 is operated to the neutral position 18N and the check valves 13 and 14 are operated to be open (the hydraulic cylinder 7 operates as a suspension mechanism) (step S3), the control cycle T12 starts to be counted. (Step S4), the operating position (expanded position) of the hydraulic cylinder 7 is detected and stored (Step S5).

  When the control cycle T12 elapses (see time point T2 in FIG. 5), the intermediate position detection means 42 operates all the hydraulic cylinders 7 past the set time T11 from time point T2 (see time point T2 to time point T1 in FIG. 5). The maximum position A1 and the minimum position A2 of the operation of the hydraulic cylinder 7 are detected from the (extension / contraction position), and an intermediate position B1 between the maximum and minimum positions A1 and A2 (a central position between the maximum and minimum positions A1 and A2) ) Is detected (steps S6, S7, S8).

  As shown in FIG. 5, the maximum position A1 is a position where the operating position of the hydraulic cylinder 7 is displaced to the airframe ascending side and then displaced to the airframe descending side (a position where the hydraulic cylinder 7 is switched from the expansion operation to the contracting operation). . The minimum position A2 is a position where the operating position of the hydraulic cylinder 7 is displaced to the aircraft lowering side and then displaced to the aircraft raising side (a position at which the hydraulic cylinder 7 switches from the contracting operation to the extending operation).

  In this case, the operation position (extension / contraction position) of the hydraulic cylinder 7 from the time when the previous control cycle T12 has elapsed to the time when the current control cycle T12 has elapsed (see time T2 in FIG. 5) The operation position (extension / contraction position) is stored as the operation position (extension / contraction position), and the previous operation position (extension / contraction position) of the hydraulic cylinder 7 from the time T1 past the set time T11 from the time T2 is erased. A part of the operation position (extension / contraction position) of the hydraulic cylinder 7 stored in the control device is updated.

In steps S6 and S7, if the set time T11 is set to be slightly longer than one cycle of the resonance frequency of the hydraulic cylinder 7 (suspension mechanism), one maximum position A1 and one minimum are set during the set time T11. A position A2 is detected, and in this case, an intermediate position B1 is detected from one maximum and minimum position A1, A2 (step S8).
In Steps S6 and S7, when the set time T11 is set to be somewhat long, operation displacements that become a plurality of peak positions and valley positions during the set time T11 are detected. In this case, the maximum peak position among the plurality of peak positions is regarded as the maximum position A1, the minimum valley position among the plurality of valley positions is regarded as the minimum position A2, and the maximum position A1 and the minimum position are considered. An intermediate position B1 is detected from A2 (step S8).

When the intermediate position B1 is detected, the intermediate position B1 is compared with the target range H1 (step S9). If the intermediate position B1 is deviated from the target range H1 toward the aircraft lowering side, the integration means 43 sets the number N of integrations. “1” is subtracted (step S10). When the intermediate position B1 deviates from the target range H1 to the aircraft ascending side, “1” is added to the number of times of integration N by the integration means 43 (step S11). When the intermediate position B1 is within the target range H1, addition and subtraction to the integration number N are not performed.
Next, the process proceeds to step S4, where steps S4 to S11 are performed, and the detection of the intermediate position B1, the comparison between the intermediate position B1 and the target range H1, the addition and subtraction of the number N of integrations are performed, and again step S4 Steps S4 to S11 are repeated.

[5]
Next, the second half of the control of the hydraulic cylinder 7 will be described with reference to FIGS.
FIG. 9A is an explanatory view showing the operating displacement of the hydraulic cylinder 7. FIG. 9B is an explanatory diagram showing changes in the operating speed of the hydraulic cylinder 7. The operation displacement shown in area A of FIG. 9 (a) is the operation displacement generated by the unevenness of the ground in the hydraulic cylinder 7, and the operation speed shown in area A of FIG. 9 (b) is A in FIG. 9 (a). The operating speed corresponds to the operating displacement shown in the area. The operation speed V1 shown in FIG. 9B is an operation speed generated after the operation displacement S1 is generated.

  That is, when an operating displacement on the airframe ascending side due to the unevenness of the ground occurs in the hydraulic cylinder 7, a returning displacement to the airframe descending side occurs after this operating displacement, and the operation returns to the target range H1. When an operation displacement on the airframe lowering side due to the unevenness of the ground occurs in the hydraulic cylinder 7, a return displacement to the airframe ascending side is generated after this operation displacement, and the operation returns to the target range H1. Therefore, when an operation displacement due to unevenness of the ground occurs in the hydraulic cylinder 7, even if the operation of the hydraulic cylinder 7 deviates from the target range H1, an operation speed in a direction in which the operation returns to the target position H1 later occurs. The operation speed in the direction in which the operation of the hydraulic cylinder 7 deviates from the target range H1 and returns to the target range H1 occurs within about ¼ of the natural resonance period of the hydraulic cylinder 7.

  The operation displacements S2 and S3 shown in the area B of FIG. 9A are operation displacements when the earth and sand are scraped by the connected front dozer. The operating speed shown in the B area of FIG. 9B is an operating speed corresponding to the operating displacements S2 and S3 shown in the B area of FIG. 9A. The operation speed V2 illustrated in FIG. 9B indicates a virtual operation speed corresponding to the operation displacement S2.

In other words, when the hydraulic cylinder 7 undergoes an operating displacement on the airframe ascending side due to the weight of the raked sand by the front dozer, no return displacement to the airframe descending side occurs. Even if the return displacement may occur, the return displacement becomes small and the operation does not return to the target range H1. That is, when the front loader scoops the earth and sand and the hydraulic cylinder 7 is displaced on the upper side of the body due to the weight of the skimming earth and sand, the hydraulic cylinder 7 is out of the target range H1. Therefore, the return displacement toward the target range H1 does not occur, and the operating speed such as the virtual operating speed V2 does not occur.
When earth and sand are discharged by the front dozer, the load caused by the weight of the earth and sand that has been applied to the traveling machine before the earth and sand is released is eliminated, so that the operating displacement generated in the hydraulic cylinder 7 is moved to the lower side of the body. It becomes. Therefore, when the earth and sand discharge is performed, the operation of the hydraulic cylinder 7 stops at a position outside the target range H1 and is different from the case where the earth and sand are scraped in the direction of the displacement of the operation displacement. This is the same as the case where the earth and sand are raked in that the return displacement toward the range H1 does not occur and the operation speed in the direction to return to the target range H1 does not occur.

The stop state detection means 38 detects the operation stop state of the hydraulic cylinder 7 based on the information detected by the operation position sensor 37.
That is, the operation data of the hydraulic cylinder 7 detected by the operation position sensor 37 is differentiated to calculate the operation speed of the hydraulic cylinder 7. After the operation of the hydraulic cylinder 7 deviates from the target range H1, whether or not there is an operation speed at which the operation of the hydraulic cylinder 7 returns to the target range H1, and the operation speed of the return displacement when the return displacement operation speed occurs. And when it is determined that the operating speed of the return displacement has not occurred between the time when the operation of the hydraulic cylinder 7 deviates from the target range H1 and the set measurement time elapses, and the operating speed of the return displacement Even if it occurs, if it is determined that the operating speed value of the generated return displacement is smaller than the set reference value, the hydraulic cylinder 7 is stopped after the operation of the hydraulic cylinder 7 is out of the target range H1. It is detected that As the set measurement time, a time longer than ¼ of the natural resonance period of the hydraulic cylinder 7 is set.

When the detection of the intermediate position B1, the comparison between the intermediate position B1 and the target range H1, and the addition / subtraction of the number of times of integration N are performed (steps S4 to S11), the control means 40 performs the stop state detection means 38 each time. It is determined whether or not the operation stop state has been detected (step S12). When it is determined that the operation stop state is detected by the stop state detection unit 38, the control unit 40 measures an elapsed time t after the operation stop state is detected.
The auxiliary control unit 45 operates the integration number setting unit 44 to set the lower side set integration number ND1 (corresponding to the set integration number) and the upside set integration number NU1 (corresponding to the set integration number) as follows. .

  A first reference number NDS and a second reference number NDL, a first reference number NUS, and a second reference number NUL are set in the control device 35. The auxiliary control means 45 first sets the second reference number NDL as the lower side set integration number ND1 and sets the second reference number NUL as the upside set integration number NU1 by the integrated rotation speed setting means 44 ( Step S1). In this case, the first reference number NDS is set to a value smaller than the second reference number NDL, and the first reference number NUS is set to a value smaller than the second reference number NUL.

  In the state where the second reference number NDL is set as the descending side set integration number ND1 (corresponding to a state where the operation frequency is low) and the second reference number NUL is set as the upside set integration number NU1 (the operation frequency is low) The auxiliary control means 45 sets the first reference number NDS as the lower side set integration number ND1 by the integration number setting unit 44 (the operation frequency is equal to the state). The first reference number NUS is set as the ascending-side set integration number NU1 (corresponding to a state where the operation frequency increases) (step S14).

A set elapsed time t0 after the operation stop state is detected by the stop state detecting means 38 is set in the control device 35. As the set elapsed time t0, a time necessary for performing adjustment to return the operation of the hydraulic cylinder 7 in the operation stopped state to the target range H1 is set.
The first reference number NDS is maintained as the lower side set integration number ND1 until the elapsed time t from the detection of the operation stop state by the stop state detecting means 38 reaches the set elapsed time t0, and the higher side set integration is maintained. The first reference number NUS is maintained as the number of times NU1. When the elapsed time t from the detection of the operation stop state by the stop state detecting means 38 reaches the set elapsed time t0, it is set back to the original second reference number NDL as the lower set cumulative number of times ND1, and increased. The side set integration number NU1 is set back to the original second reference number NUL.

  As described above, the control unit 40 sets the lower side set integration number ND1 and the upside set integration number NU1, and compares the integration number N with the lower side set integration number ND1 and the upside set integration number NU1, When it is determined that the cumulative number N has reached the lower set cumulative number ND1 (below) (step S16), it is determined that the front part of the fuselage is lowered and the fuselage is in a forward-lowering state with respect to the ground, and the control valve 18 is operated to the raised position 18U, and the check valves 13 and 14 are operated to operate (step S17).

  As a result, as described in [3] above, the hydraulic cylinder 7 expands and the fuselage is in a state where the pressure in the oil chamber 7b and the oil passage 10 of the hydraulic cylinder 7 is maintained at the set pressure MP1 by the relief valve 28. The front of the rises. When the hydraulic cylinder 7 is extended by an amount corresponding to the difference between the intermediate position B1 and the target range H1 (when the intermediate position B1 enters the target range H1), the process proceeds to step S2 and the cumulative number N is set to “0”. Then, the control valve 18 is operated to the neutral position 18N, and the check valves 13 and 14 are returned to the open state (the state in which the hydraulic cylinder 7 operates as the suspension mechanism).

  When the control means 40 determines that the cumulative number N has reached the ascending-side set number NU1 (exceeds) (step S19), the control means 40 determines that the front part of the aircraft is raised and the aircraft is in a front-up state with respect to the ground. Then, the control valve 18 is operated to the lowered position 18D, and the check valves 13 and 14 are operated (step S19).

  As a result, as described in [3] above, the hydraulic cylinder 7 contracts and the fuselage is operated while the pressure in the oil chamber 7b and the oil passage 10 of the hydraulic cylinder 7 is maintained at the set pressure MP1 by the relief valve 28. The front part of the descent. When the hydraulic cylinder 7 is contracted by an amount corresponding to the difference between the intermediate position B1 and the target range H1 (when the intermediate position B1 enters the target range H1), the process proceeds to step S2 and the cumulative number N is set to “0”. Then, the control valve 18 is operated to the neutral position 18N, and the check valves 13 and 14 are returned to the open state (the state in which the hydraulic cylinder 7 operates as the suspension mechanism).

  As described above, even if steps S4 to S11 are repeated, the integration number N does not reach the lower side set integration number ND1 (not lower) (step S16), and the increase side integration number NU increases. If the set integration number NU1 is not reached (if it does not exceed) (step S18), the control valve 18 is operated to the neutral position 18N and the check valves 13 and 14 are opened (the hydraulic cylinder 7 is a suspension mechanism). Is maintained).

  Therefore, when an operation displacement occurs in the hydraulic cylinder 7 where the operation of the hydraulic cylinder 7 deviates from the target range H1 to the ascending side and the descending side of the aircraft, the operation of the hydraulic cylinder 7 returns to the target range H1, The control means 45 adopts the second reference number NDL and the second reference number NUL for normal use and on the low operation frequency side as the number of times of integration by the integration means 43, so that the control means 40 is controlled based on the detection information by the elevation detection means 41. Suspension control to move the operation of the hydraulic cylinder 7 to the target range side in a state where the frequency of operating the control valve 18 is lowered so that the operation of the hydraulic cylinder 7 moves to the target range side. Performed (steps S1-12, 16-19).

  When the hydraulic cylinder 7 is operated so that the displacement of the hydraulic cylinder 7 deviates from the target range H1 to the airframe ascending side and the airframe descending side, the hydraulic cylinder 7 is actuated as if the front loader scoops and discharges the earth and sand. When the auxiliary control means 45 does not return to the target range H1, the auxiliary control means 45 is based on the detection information from the stop state detection means 38 and is used as the second reference on the low operation frequency side for normal use as the number of integrations by the integration means 43. By using the first reference number NDS and the first reference number NUS on the high operating frequency side in preference to the number NDL and the second reference number NUL, the control information 40 is given priority over the detection information by the lift detection means 41. By operating the control valve 18 and increasing the frequency of operating the control valve 18 so that the operation of the hydraulic cylinder 7 moves to the target range side, the operation of the hydraulic cylinder 7 is controlled by the target range. Suspension control to move to the side is performed (step S1~19).

[First Alternative Embodiment of the Invention]
In steps S4 to S8 in FIG. 7 of the above-mentioned [Description of the Invention], the set time T11 is set slightly longer to detect a plurality of maximum positions A1 and a plurality of minimum positions A2. In this case, the intermediate position B1 in step S8 in FIG. 7 may be detected as follows.

(1) In a plurality of maximum positions A1 and a plurality of minimum positions A2, one maximum position A1 and one minimum position A2 are grouped into a plurality of sets of maximum and minimum positions A1 and A2. Separately, by detecting the intermediate position B1 in each group, a plurality of intermediate positions B1 are detected, and the average value of the plurality of intermediate positions B1 is set as the intermediate position B1 in step S8 of FIG.

(2) An average value of the maximum position A1 is detected at a plurality of maximum positions A1, an average value of the minimum position A2 is detected at a plurality of minimum positions A2, and an intermediate position is determined from the average values of the maximum and minimum positions A1 and A2. B1 is detected and set as an intermediate position B1 in step S8 of FIG.

[Second Embodiment of the Invention]
In the above-mentioned [Mode for Carrying Out the Invention] [First Another Mode for Carrying Out the Invention], the intermediate position B1 is not set to a central position between the maximum and minimum positions A1 and A2, but in front of the aircraft. The intermediate position B1 is slightly raised from the center position between the maximum and minimum positions A1 and A2 (the hydraulic cylinder 7 The intermediate position B1 may be set to a position slightly lower from the center position between the maximum and minimum positions A1 and A2 (a contraction side of the hydraulic cylinder 7). .
For example, when a work device (for example, a front loader) is mounted on the front of the machine, the intermediate position B1 is slightly raised from the center position between the maximum and minimum positions A1 and A2 (the extension side of the hydraulic cylinder 7). By setting to, the aircraft should be raised slightly forward relative to the ground.

  The present invention can be used for tractors, construction machines such as loaders, and forklifts.

DESCRIPTION OF SYMBOLS 1 Traveling device 5 Traveling machine body 7 Suspension mechanism 18 Operation change means 38 Stop state detection means 40 Control means 41 Elevation detection means 42 Intermediate position detection means 43 Integration means 45 Auxiliary control means

Claims (2)

A work vehicle in which a traveling machine body supports a traveling device via a suspension mechanism,
Lifting detection means for detecting the lifting displacement of the operation of the suspension mechanism;
An operation changing means capable of changing the operation of the suspension mechanism to the airframe rising side and the airframe lowering side;
Control means for operating the operation changing means so that the operation of the suspension mechanism moves to the target range side based on the detection information by the lifting detection means,
Comprising stop state detecting means for detecting an operation stop state of the suspension mechanism;
When the suspension mechanism is in an operation stop state, the operation change means is prioritized over the detection information by the lift detection means so that the operation of the suspension mechanism moves to the target range side based on the detection information by the stop state detection means. A work vehicle provided with auxiliary control means to be operated. A work vehicle in which a traveling machine body supports a traveling device via a suspension mechanism,
An operation changing means capable of changing the operation of the suspension mechanism to the airframe rising side and the airframe lowering side;
Intermediate position detecting means for detecting a maximum position and a minimum position of operation of the suspension mechanism and detecting an intermediate position between the maximum and minimum positions;
Integrating means for integrating the number of times the intermediate position deviates from the target range;
Control means for operating the operation changing means so that the intermediate position moves to the target range side when the number of times of integration by the integration means exceeds the set number of times of integration,
Comprising stop state detecting means for detecting an operation stop state of the suspension mechanism;
When the suspension mechanism is in an operation stop state, the operation change means is prioritized over the number of integrations by the integration means so that the operation of the suspension mechanism moves to the target range side based on the detection information by the stop state detection means. A work vehicle provided with auxiliary control means to be operated.

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