JP5513818B2 - Industrial vehicle - Google Patents

Description

  The present invention relates to an industrial vehicle having an arm and a bucket for excavating and lifting an object to be excavated such as earth and sand.

  A wheel loader, which is a typical example of such an industrial vehicle, is used for excavating accumulated sand and lifting it and loading it onto a dump truck or the like. The power generated by the prime mover is applied to the wheel via a torque converter or the like. By being transmitted, a traction force is generated on the vehicle body and the vehicle travels. The wheel loader includes an arm that can swing with respect to the vehicle body and a bucket that can swing with respect to the arm, and further includes an actuator for driving the arm and the bucket.

  In the operation using the wheel loader, the opening of the bucket brought close to the ground is directed in advance to the earth and sand side. Then, a traction force is generated on the vehicle body to travel toward the earth and sand, and the bucket is thrust into the earth and sand. Next, the arm is swung to raise and the bucket is swung so that the opening of the bucket faces upward, and the earth and sand are lifted while being loaded in the bucket. Then, the vehicle travels to the standby position of the truck, and the earth and sand lifted by swinging the bucket is loaded on the truck. Sediment loading is performed by repeating this series of operations.

  When the traction force is increased, the so-called thrust property of the bucket with respect to the earth and sand is improved, and the amount of earth and sand loaded in the bucket is increased. On the other hand, when a driving force is applied to the arm from the actuator to raise the arm, a rotation moment is generated in the work machine based on the driving force. A force acts on the earth and sand from the bucket according to the rotational moment derived from this driving force, and the upward component of this force becomes a lift force for lifting the earth and sand.

  Here, securing the traction force and securing the lift force are in a trade-off relationship. For example, if a traction force is applied to the vehicle body with the bucket thrust into the earth and sand, a reaction force equivalent to the traction force acts on the bucket from the earth and sand, and the driving force applied to the arm by the actuator is canceled by this reaction force. End up. Therefore, the lift force is generated only based on the force remaining after canceling the reaction force from the drive force. If the traction force is excessive, the drive force is offset by the reaction force and the bucket cannot be raised. .

  In particular, when a so-called combined stall occurs, a complicated operation such as fine adjustment of an accelerator pedal is required to adjust the traction force generated by the prime mover. On the other hand, Patent Document 1 proposes a wheel loader equipped with a control device that controls the rotational speed of a prime mover so that the traction force is automatically reduced and the lift force is secured when a combined stall occurs. (For example, refer to Patent Document 1).

JP-A-3-286045

  According to this wheel loader, when the combined stall occurs, the traction force is automatically reduced and the lift force is secured, so that it is possible to prevent a situation in which the arm does not rise without requiring a complicated operation. However, if a combined stall occurs during the work, the traction force is automatically reduced. Therefore, it is unavoidable that the thrust into the earth and sand is deteriorated at this time, and the work efficiency may be deteriorated. On the contrary, if the combined stall has not occurred, the traction force and the lift force are not automatically adjusted, and a complicated operation is still forced.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the working efficiency by adjusting the traction force and the lift force more precisely during the excavation work of an industrial vehicle.

  The present invention has been made in view of the above circumstances, and a wheel loader according to the present invention is provided on a vehicle body so as to be swingable, and includes an arm and a bucket for excavating and lifting an object to be excavated, the arm and the An actuator that applies a driving force to the bucket and generates a lift force that acts on the object to be excavated from the bucket; a control device that calculates a target traction force that acts on the vehicle body in accordance with the loading posture of the arm and bucket; and And a prime mover that is controlled by a control device and generates the target traction force.

  Here, the arm and the bucket are attached so as to swing with respect to the vehicle body. Of the driving force applied to the arm by the actuator, the component of the traction force acting direction (typically the horizontal component) is generally Specifically, it tends to increase as the cargo handling posture of the arm and bucket changes so as to lift the object to be excavated. Therefore, if the work to lift the object to be excavated is performed under the condition that the driving force and the traction force applied to the arm and bucket by the actuator are constant, the driving force remaining after the reaction force corresponding to the traction force is canceled is And it changes following the change of the cargo handling posture of the bucket. In other words, when the cargo handling posture of the arm and bucket changes while the driving force and the traction force are constant, the lift force changes accordingly.

  According to the present invention, the prime mover is controlled so that the target traction force according to the cargo handling posture of the arm and bucket acts on the vehicle body. For this reason, even if a cargo handling attitude | position changes, a lift force can be controlled automatically and appropriately. For this reason, during the process from excavating the excavation work to lifting it, the work can be performed without requiring a complicated operation, and the work efficiency is improved.

  It is preferable that the control device calculates a target traction force that increases as the cargo handling posture of the arm approaches horizontal. Here, generally, the closer the cargo handling posture of the arm is to the horizontal, the greater the component of the traction force acting on the object to be excavated from the bucket based on the driving force applied to the arm by the actuator. Lift force can be secured against reaction force equivalent to tractive force. For this reason, in the process of bringing the cargo handling posture closer to the horizontal, the lift force can be continuously secured even if the target traction force increases. Therefore, by setting the target traction force as described above, it is possible to increase the traction force while securing the lift force, improving the thrust of the work implement and improving the work efficiency.

  The actuator includes a hoist cylinder that swings the arm, and a bucket cylinder that swings the bucket, and the control device is configured based on an angle of the arm with respect to the vehicle body or an extension amount of the hoist cylinder. The cargo handling posture may be detected. The control device may further detect the cargo handling posture based on an angle of the bucket with respect to the vehicle body or an extension amount of the bucket cylinder.

  The control device may further calculate the target traction force acting on the vehicle body according to a driving force applied to at least the arm or the bucket by the actuator. As a result, even if the driving force changes, this can be absorbed and the optimum traction force and lift force can be generated.

  A target lift force map storage unit that stores a plurality of target lift force maps indicating the relationship between the cargo handling posture and the target lift force, and a lift force command device that receives an input of a target lift force map command to be selected from an operator, The control device may select one of the plurality of target lift force maps according to a command from the lift force commander, and calculate the target lift force with reference to the selected target lift force map. Good. Accordingly, for example, the lift force can be set and changed in accordance with the specific gravity, viscosity, inclination angle, etc. of the excavation object.

  A target speed map storage unit for storing a target speed map for calculating the target traction force and a target speed of the prime mover necessary for generating the target traction force; and a torque converter connected to the prime mover. The control device further selects one of the plurality of target rotational speed maps according to a ratio between the rotational speed of the input shaft of the torque converter and the rotational speed of the output shaft of the torque converter, The target rotational speed may be calculated with reference to the selected target rotational speed map. Thereby, even when the stall of the torque converter occurs, the traction force adjustment control can be accurately performed according to the maximum absorption torque of the torque converter determined according to the ratio.

  The control device determines whether or not excavation work is being performed on the object to be excavated by the arm and the bucket, and when it is determined that excavation work is being performed, It is preferable to execute control of the prime mover.

  As described above, according to the present invention, since the traction force and the lift force are finely adjusted according to the handling posture of the arm and the bucket, the working efficiency is improved.

It is a side view of a wheel loader shown as an example of an industrial vehicle concerning an embodiment of the present invention. It is a block diagram which shows typically the structure of the wheel loader shown in FIG. It is the elements on larger scale of Drawing 1, and is an explanatory view of the relation between tractive force and lift force. (A) is a graph which shows the relationship between tractive force and lift force, (b) is a graph which shows the relationship between an arm angle and the horizontal direction component of arm force. It is explanatory drawing of the relationship between an arm angle, tractive force, and lift force. FIG. 2 is a torque diagram of the wheel loader shown in FIG. 1 and is a graph showing the relationship between the rotational speed of the prime mover and the traction force. It is a flowchart which shows the procedure of the process which the controller shown in FIG. 3 performs. It is a map for calculating | requiring the target lift force according to an arm angle. FIG. 8 is an operation diagram of excavation work performed while executing the process shown in FIG. 7. It is a map for calculating | requiring the target tractive force according to an arm angle. It is a map for calculating | requiring the target rotation speed according to speed ratio and target tractive force. It is a map for calculating | requiring the target rotation speed according to an arm angle.

  Embodiments of the present invention will be described below with reference to these drawings. Here, a wheel loader is illustrated as an industrial vehicle according to an embodiment of the present invention, and this wheel loader is assumed to be grounded on a horizontal ground. Therefore, although the traction force described later is assumed to work in the horizontal direction, the direction of application of the traction force and other forces, and the orientation of the reference plane for obtaining the arm angle and bucket angle are appropriately changed according to the inclination of the ground.

[overall structure]
A wheel loader 1 shown in FIG. 1 includes a vehicle body 2, and a pair of left and right wheels 3 and 4 are provided at a lower front portion and a lower rear portion of the vehicle body 2. A base end portion of the arm 5 is swingably attached to the front portion of the vehicle body 2, and a bucket 6 is swingably attached to the distal end portion of the arm 5. Hereinafter, for convenience of explanation, these arms 5 and buckets 6 may be collectively referred to as “work machines”.

  The actuator of the work machine includes a hoist cylinder 7 and a bucket cylinder 9. The hoist cylinder 7 is stretched between the vehicle body 2 and the arm 5, and the arm 5 swings around the left and right axis with respect to the vehicle body 2 according to the expansion and contraction of the hoist cylinder 7. A lever 8 is fixed to the rear portion of the bucket 6, and a bucket cylinder 9 is bridged between the lever 8 and the arm 5. As the bucket cylinder 9 expands and contracts, the bucket 6 swings around the left and right axes with respect to the arm 5.

  A prime mover 10 that generates power is mounted on the rear portion of the vehicle body 2, and the prime mover 10 is connected to wheels 3 and 4 via a torque converter 11, a transmission 12, a propeller shaft 13, and axles 14 and 15. By transmitting the power generated by the prime mover 10 to the wheels 3 and 4, a horizontal traction force is generated in the vehicle body 2 and the wheel loader 1 can travel. The prime mover 10 may be constituted by a single reciprocating internal combustion engine or may be a so-called hybrid type in which an electric motor / generator is attached thereto. The transmission 12 can set a plurality of forward shift stages and a plurality of reverse shift stages.

  Further, a hydraulic pump 16 such as a piston pump is directly connected to the output shaft of the prime mover 10, and the hydraulic pump 16 is driven based on the power generated by the prime mover 10.

  In the cabin 17 provided in the upper part of the vehicle body 2, various operating devices 18 are provided for an operator to perform traveling operation and excavation work. The operating device 18 includes, for example, a steering 19 for steering, an accelerator pedal 20 for operating the output of the prime mover 10, a shift lever 21 for shifting operation, an arm 5 and a working machine for operating swinging of the bucket 6. In addition to the operation lever 22, switches 23, 24 and the like described later are included.

  In the excavation work, the accelerator pedal 20 is stepped on to advance the vehicle body 2 toward the accumulation portion of the excavation target 50 such as earth and sand. At this time, the shift lever 21 is operated in advance, and, for example, the gear position is set to the lowest speed stage for forward traveling in order to increase the torque transmitted to the wheels 3 and 4. Further, by operating the work operation lever 22 in advance, the arm 5 is lowered and the opening of the bucket 6 is directed forward so that the excavation target object 50 can be dug up from the lower part of the accumulation portion. Therefore, the lower end of the bucket 6 is positioned close to the ground at the start of the work. In this state, the bucket 6 moves forward and thrusts the bucket 6 into the lower part of the depositing section, and then the work implement operating lever 22 is operated to raise the arm 5 and to open the bucket 6 upward. As the arm 5 moves up, an upward lift force acts on the excavation target 50, and the excavation target 50 in the bucket 6 is lifted. Then, after traveling to a predetermined location, the arm 5 and the bucket 6 are swung, and the excavation object 50 in the bucket 6 is lowered.

[Hydraulic system]
As shown in FIG. 2, the hydraulic oil discharged from the hydraulic pump 16 is sent to the hoist cylinder 7 and the bucket cylinder 9 via the control valve 26. The control valve 26 is driven and controlled according to the position of the work implement operating lever 22, and hydraulic oil is supplied to the cylinders 7 and 9 independently of each other. For this reason, the arm 5 and the bucket 6 swing independently of each other according to the lever operation in the cabin 17.

[Control system]
Further, the wheel loader 1 is provided with a controller 30 composed of a microcomputer or the like. On the input side of the controller 30, a first rotation speed sensor 31 that detects the rotation speed of the input shaft of the torque converter 11, a second rotation speed sensor 32 that detects the rotation speed of the output shaft of the torque converter 11, and the accelerator pedal 20. Pedal sensor 33 for detecting the operation amount, shift sensor 34 for detecting the position of the shift lever 21, pump pressure sensor 35 for detecting the pump pressure, cylinder supply pressure sensor 36 for detecting the pressure supplied to the hoist cylinder 7, cargo handling A cargo handling posture detector 37 for detecting the posture, changeover switches 23 and 24, and the like are connected.

The “loading attitude” refers to the attitude of the working machine with respect to the vehicle body 2 or a reference plane such as the ground or a horizontal plane. Specific numerical values thereof include, for example, a fulcrum P of the arm 5 with respect to the vehicle body 2 as shown in FIG. ₁ and the angle θ formed by the connection between the point of action P ₃ for the excavation target located at the front lower end of the bucket 6 and the ground (horizontal plane) serving as the reference plane. The cargo handling posture detector 37 only needs to be able to output a signal that enables the controller 30 to detect the cargo handling posture through an internal process. Typically, the arm angle for detecting the angle of the arm 5 with respect to the vehicle body 2 is detected. The sensor 38, the bucket angle sensor 39 for detecting the angle of the bucket 6 with respect to the vehicle body 2, and the like are realized. Since the angles of the arm 5 and the bucket 6 are determined in accordance with the extension amounts of the hoist cylinder 7 and the bucket cylinder 9, respectively, the extension amount of the hoist cylinder extension sensor 40 and the extension amount of the bucket cylinder 9 are detected. This can also be realized by the bucket cylinder extension amount sensor 41 or the like to be detected. Here, for convenience, a case where an arm angle sensor 38 and a bucket angle sensor 39 are employed as the cargo handling posture detector 37 is illustrated.

  A motor control module (hereinafter referred to as “ECM”) 42 for controlling the operation of the motor 10 is connected to the output side of the controller 30, and this ECM 42 drives a mechanism for changing the rotational speed of the motor 10. It is the structure to control. Therefore, the controller 30 can execute control to indirectly adjust the rotational speed of the prime mover 10 by outputting a command to the ECM 42. The form of the mechanism that is driven and controlled by the ECM 42 is not particularly limited.

  The controller 30 executes a program stored in the memory area, thereby adjusting the rotational speed of the prime mover 10 according to the cargo handling posture during the excavation work, thereby obtaining the optimum traction force and lift force for the excavation work. It is supposed to be generated. In the description of this control, first, the traction force, the lift force, the cargo handling posture, the driving force of the hoist cylinder 7 (hereinafter referred to as “the hoist cylinder force”) in the wheel loader 1 equipped with the work machine having the general link mechanism shown in FIG. ) And the rotational speed of the prime mover 10 will be described in detail.

[Relationship between lift force, traction force, hoist cylinder force, and loading attitude]
In FIG. 3, reference symbol P ₁ is a swing fulcrum for the arm 5 with respect to the vehicle body 2, reference symbol P ₂ is a swing fulcrum for the arm 5 of the hoist cylinder 7, and reference symbol P ₃ is set at the front lower end of the bucket 6 The excavation action point at which a force acts on the object, symbol P _4, is a swing fulcrum for the bucket 6 of the arm 5. Each force acting in the horizontal direction is positive in the forward direction, and each force acting in the vertical direction is positive in the upward direction. Each angle θ, θ _A , and θ _B , which will be described later, has a ground plane (here, a horizontal plane) as a reference plane, and a counterclockwise side from the reference plane in the left side view is positive.

When the hoist cylinder 7 extends, a hoist cylinder force F is applied to the arm 5. Then, a rotational moment about the point P ₁ is generated in the arm 5 and the bucket 6. At this time, the bucket cylinder force F _B is acting on the bucket cylinder 9, and the arm 5 and the bucket 6 also generate a rotational moment about the point P ₁ based on the bucket cylinder force F _B. From these facts, the rotational moment M around the point P ₁ is expressed as follows.

L ₁ is the shortest distance from the point P ₁ to the axis of the hoist cylinder 7, that is, the moment arm distance for calculating the moment around the point P _{1 applied} by the hoist cylinder force F, and is a function of the arm angle θ _A. It becomes. M _a1 is the shortest distance (moment arm) from the point P ₁ to the axis of the bucket cylinder 9 and is a function of the arm angle θ _A and the bucket angle θ _B.

During excavation work, a force (hereinafter referred to as “working force”) can be applied to the object to be excavated from the excavation action point P ₃ based on the rotational moment corresponding to the hoist cylinder force F. Here, as will be described later, when the traction force _FT is not considered, the force when the working force is applied only in the horizontal direction is defined as the maximum horizontal force F _x, and the force when the operation force is applied only in the vertical direction. The maximum normal force F _{y is} assumed.

From the balance of forces, the ratio between the maximum horizontal force F _x and the maximum vertical force F _y is the angle θ formed by the connection between the points P ₁ and P ₃ and the ground (here, the horizontal plane) as shown in equation (2). Dependent.

The angle θ is an angle that can specifically represent the “loading attitude” as a numerical value as described above, and is a function of the arm angle θ _A and the bucket angle θ _B as represented by equation (3). The arm angle θ _A is an angle formed by the connection between the points P ₁ and P ₄ and the ground, and the bucket angle θ _B is an angle formed by the connection between the points P ₃ and P ₄ and the ground. These angles θ _A and θ _B can also be handled as a numerical value representing the cargo handling posture. Note that L _A is the distance between the points P ₁ and P ₄ , and L _B is the distance between the points P ₃ and P ₄ .

From equations (2) and (3), the maximum horizontal force F _x and the maximum vertical force F _y acting on the excavation object are functions of the arm angle θ _A and the bucket angle θ _B as represented by equation (4). .

Note that the rotational moment centered on P ₁ due to the maximum horizontal force F _x acting at the excavation operating point P ₃ is equal to the rotational moment M expressed by Equation (1). Therefore, the maximum horizontal force F _x , the hoist cylinder force F, and the bucket cylinder force F _B satisfy the relationship of Expression (5).

If the bucket 6 does not rotate, the bucket cylinder force F _B satisfies the relationship expressed by the equation (6). From the equations (5) and (6), the maximum horizontal force F _x and the hoist cylinder force F are The relationship of the formula (7) is satisfied.

Note that M _{a1 to} M _a4 are moment arms, which are functions of the arm angle θ _A and the bucket angle θ _B.

Here, and tractive force F _T is generated in the vehicle body 2 during excavation work, if the action is該牽attraction F _T drilling object in excavation work point P _3, the working force, acting from the drilling object 50 It cancels out by the reaction force equivalent to the traction force. Since traction F _T and its reaction force acting in the horizontal direction, the force remaining after canceling a reaction force from the work force (hereinafter, this force is referred to as "Zanryoku") horizontal component F _x 'is the formula (8 ).

Since the lift force _FL is a vertical component of this residual force, it can be expressed by equation (9) from equations (4), (7), and (8).

α and β are functions of the arm angle θ _A and the bucket angle θ _B and can be expressed by the following equation (10).

Thus lifting force F _L is a function of the traction force F _T, and the hoist cylinder force F, the handling and orientation (i.e. the arm angle theta _A and the bucket angle theta _B). L _A and L _B are design parameters of the work machine and can be handled as constants.

Equation (9) and as shown in FIG. 4 (a), when the traction force F _T increases, the reaction force is residual force decreases with increasing lift force F _L is reduced. Therefore, we know that in order to obtain a large lifting force F _L during drilling operations it is necessary to suppress the traction F _T. On the other hand, as shown in FIG. 4B, the working force increases in the horizontal share as the arm angle θ _A decreases and the arm 5 rises. Although depending on the setting method of the link mechanism, during excavation work, this increase rate is generally larger than the change rate of work force due to changes in the arm angle θ _A and bucket angle θ _B.

Accordingly, as shown in FIG. 5, reducing the arm angle theta _A under acting constant traction force F _T, it increases the horizontal component F _x 'residual force, lift force F _L is increased. In other words, while reducing the arm angle theta _A, even if the traction force F _T is increased it is possible to ensure a constant lifting force F _L. Incidentally, the lift force F _L are the vertical component of the residual force of the working force generated on the basis of the hoist cylinder force F, the lift force F _L is also increased if increased hoist cylinder force F.

[Relationship between tractive force, motor speed and speed ratio]
FIG. 6 shows the transition of torque transmitted from the prime mover 10 according to the rotational speed of the prime mover 10 (see torque curves ET1 to ET3). In the present embodiment, the hydraulic pump 16 is directly attached to the prime mover 10, and the torque output from the prime mover 10 is absorbed by the load of the hydraulic pump 16, and the absorption torque of the hydraulic pump 16 increases as the load increases. Referring to the figure, the torque curves ET2 and ET3 taking into account the absorption torque of the hydraulic pump 16 shift downward with respect to the torque curve ET1 representing the transition of the net torque, and the torque curve ET3 in the relief state is in the no-load state. It is below the torque curve ET2. Note that, during excavation work, a transition approximate to the torque curve ET3 in the relief state is shown.

FIG. 6 illustrates the transition of the maximum torque that can be absorbed by the torque converter 11 according to the rotational speed of the prime mover 10 according to the speed ratio (see torque curves TT1 to TT11). Since the maximum absorption torque of the torque converter 11 is to be transmitted to the wheels 3, 4 via the transmission 12, the maximum absorption torque is proportional to the traction force F _T generated in the vehicle body 2. According to the transition of each of the torque curves TT1 to TT11, the maximum absorption torque simply increases while the rotational speed of the prime mover 10 increases within a predetermined range regardless of the value of the gear ratio. Therefore, increasing the rotational speed of the prime mover 10, the traction force F _T will increase.

The “speed ratio” refers to a value obtained by dividing the output rotational speed of the torque converter 11 by the input rotational speed, and a speed ratio of 0 indicates that the torque converter 11 is stalled. In the present embodiment shows a case where traction force maximum absorption torque is increased F _T is increased for a certain rotational speed as when the speed ratio is small, this is an example. During excavation work in which the bucket 6 is thrust into the excavation target, the speed ratio tends to be a small value, and generally falls within a numerical range from 0 to 0.4.

  Next, a process executed by the controller 30 will be described along a procedure with reference to FIG. Note that the series of processes shown in FIG. 7 is repeatedly performed at predetermined control cycles (for example, 10 msec) while the ignition switch of the wheel loader 1 is ON, for example.

  First, the controller 30 inputs a signal from sensors connected to the input side (step S1), and determines whether or not excavation work is being performed based on the input signal (step S2). The determination of whether or not excavation work is in progress is made based on, for example, the position of the shift lever 21, the pump pressure, and the speed ratio. That is, based on the input signal from the shift sensor 34, the shift lever 21 is at a position where, for example, the lowest speed stage for forward traveling is set, and the pump pressure is greater than or equal to a predetermined value based on the input signal from the pump pressure sensor 35. Based on the input signals from the first rotation speed sensor 31 and the second rotation speed sensor 32, it is determined whether or not the speed ratio is not more than a predetermined value (for example, not more than 0.5). If all of these conditions are satisfied, the excavation operation is being performed, otherwise the excavation operation is not being performed.

  If it is determined that the excavation work is not being performed (S2: NO), based on the input signal from the pedal sensor 33, the prime mover corresponding to the amount of operation of the accelerator pedal 20 with reference to the map for the travel mode stored in the memory area in advance. A target rotational speed of 10 is obtained, a command is given to the ECM 42 in accordance with the obtained rotational speed (step S17), and a series of processing ends. The ECM 42 drives and controls the prime mover 10 so that the rotational speed of the prime mover 10 becomes the target rotational speed based on a command from the controller 30.

If it is determined that excavation work is in progress (S2: YES), the target lift force map stored in advance in the memory area is read (step S3). As illustrated in FIG. 8 (a), the target lift force map is a map for determining a target lift force corresponding to the arm angle theta _A. However, the relationship between the target lift force and the arm angle θ _A may be set in any way. For example, a constant target lift force may be set regardless of a change in the arm angle θ _A (see map M1), and the target lift force increases as the arm angle θ _A decreases and the arm 5 moves up. It may be set (see map M2). Here, for convenience, it is assumed that only the map M1 is stored in the memory area, and the map M1 is always read in step S3.

Next, a cargo handling posture, a target lift force, a hoist cylinder force, and the like are respectively calculated (step S4). Here, based on input signals from the arm angle sensor 38 and the bucket angle sensor 39, the arm angle θ _A and the bucket angle θ _B are obtained as the cargo handling posture. The target lift force is obtained according to the arm angle θ _A by referring to the target lift force map read in step S3. The hoist cylinder force is calculated based on an input signal from the cylinder supply pressure sensor 36, and each moment arm is calculated based on the arm angle θ _A and the bucket angle θ _B.

Next, the target traction force is calculated (step S5). The target traction force is obtained based on the arm angle θ _A , bucket angle θ _B , target lift force, hoist cylinder force F, and each moment arm calculated in step S4 using equation (9).

  Next, the target rotational speed is calculated (step S6). In the memory area, torque curves TT1 to TT11 (see FIG. 6) showing different transitions according to the speed ratio are stored in advance as a target rotational speed map. In calculating the target rotational speed, a target rotational speed map corresponding to the speed ratio calculated in step S2 is selected from a plurality of target rotational speed maps. When the speed ratio pitch of the torque curves TT1 to TT11 is finite as in the present embodiment, for example, the target rotation speed map may be selected after performing the fraction processing of the detected speed ratio. .

  Next, by referring to the selected target rotational speed map, the target rotational speed is obtained according to the target traction force calculated in step S5. Note that the target rotational speed map uses only the range in which the traction force (maximum absorption torque) simply increases with respect to the increase in rotational speed in the torque curves TT1 to TT11.

  Next, a command is given to the ECM 42 in accordance with the target rotational speed (step S7), and a series of processing ends. Based on a command from the controller 30, the ECM 42 drives and controls the prime mover 10 so that the rotational speed of the prime mover 10 becomes the target rotational speed calculated in step S6.

FIG. 9 is an operation diagram of excavation work performed while repeating the processing shown in FIG. Immediately after the start of excavation work arm angle theta _A becomes a large value, in order to ensure a desired lift force F _L which is obtained by the map M1 of FIG. 8 (a), the general target pulling force F _T is in a relatively small value Thus, the rotational speed of the prime mover 10 is set to a predetermined work start rotational speed. Of course, the target lift force _FL is set to a value sufficiently larger than 0 so that the excavation object 50 in the bucket 6 can be lifted. That is, the target pulling force F _T is hoist cylinder force is set to a sufficiently small value is not be completely canceled by the reaction force of the pulling force.

Arm 5 is raised by the arm angle theta _A becomes smaller, the handling attitude approaches horizontal, since the constant target lifting force F _L is set according to the map M1, in general the value of the target pulling force F _T Gradually increases, and the rotational speed of the prime mover 10 gradually increases from the work start rotational speed. At this time, since the target rotational speed map is set so that the rotational speed simply increases with respect to the increase in traction force, a sudden change in the rotational speed of the prime mover 10 can be avoided.

To act continuously same lift force F _L is the increase in the course of the arms 5, it is possible to satisfactorily perform lifting excavation object 50. Since the traction force F _L thereon increases, thrusting is improved as the arm 5 rises. Therefore, more excavation objects 50 can be loaded in the bucket 6 from the accumulation part.

  Thus, by controlling the traction force according to the handling posture, it is possible to improve the thrust while securing the lift force, and it is possible to increase the loading amount of the excavation object per work. . Therefore, it is not necessary to generate unnecessary traction force for securing the lift force, and the output of the prime mover 10 during excavation work can be reduced. Therefore, it is possible to suppress the fuel consumption to the maximum while securing the maximum excavation amount.

  In determining the target traction force, the hoist cylinder force is used as an input parameter. For this reason, even if the load of the hoist cylinder 7 fluctuates, the target traction force is determined following the load fluctuation. Specifically, when the hoist cylinder force decreases, the lift force decreases according to the decrease, so that the target traction force decreases together so as to offset the decrease. On the other hand, the target lift force is determined irrespective of the hoist cylinder force. Thus, even when the load of the hoist cylinder fluctuates and the lift force may decrease, a desired lift force can be applied to the excavation target object 50, and the excavation target object 50 is reliably lifted. Can be done.

  The control for automatically adjusting the traction force according to the cargo handling posture or the like is executed when the controller 30 determines that excavation work is being performed. For this reason, during this determination, the worker does not have to perform complicated work such as fine adjustment of the accelerator pedal 20 to adjust the rotational speed of the prime mover 10, and the wheel loader during excavation work. The operation 1 can be easily performed.

  Although the embodiment of the present invention has been described so far, the above configuration and the contents of the processing executed by the controller can be appropriately changed within the scope of the present invention.

  For example, a plurality of target lift force maps M1, M2 shown in FIG. 8 may be stored in the memory area of the controller 30. At this time, the operator may be able to instruct which of the plurality of target lift force maps M1 and M2 to calculate the target lift force by operating the changeover switch 23 in the cabin 17. .

In this case, an input signal from the changeover switch 23 is input to the controller 30 in step S1, and a target lift force map to be referred to is selected based on the input signal in step S3. In step S4, the target lift force is calculated based on the arm angle θ _A by referring to the selected target lift force map. As described above, the target lift force map M2 is set so that the target lift force increases as the arm angle θ _A decreases. By instructing the changeover switch 23 to refer to the map M2, a larger lift force can be applied in the latter half of the excavation work in which the weight of the excavation object loaded in the bucket 6 increases. it can. For this reason, for example, even when the specific gravity or viscosity of the excavation target is large, or even when the inclination angle of the accumulation portion of the excavation target is steep, the lifting can be reliably performed.

In the above embodiment, the arm traction angle θ _A , the bucket angle θ _B , the target lift force, and the hoist cylinder force F are input parameters, and the target traction force is calculated using Equation (9). It is not limited to the method.

For example, any of the variables in equation (9) may be made constant. For example, although the bucket angle θ _B is changed following the change in the arm angle θ _A , in general, the change in the sharing ratio between the vertical component and the horizontal component of the working force accompanying the change in the bucket angle θ _B is Smaller than that of the angle θ _A. Therefore, only the arm angle θ _A may be used as a specific numerical value of the cargo handling posture that is an input parameter for calculating the target traction force. The hoist cylinder force F can also be made constant as appropriate.

A target traction force map for calculating the target traction force according to these input parameters may be stored in the controller 30 in advance. When the target traction force is calculated, the target lift force is determined according to the cargo handling posture and the hoist cylinder force at that time. Therefore, it is not necessary to use the target lift force as an input parameter of the target traction force map. This eliminates the need to store the target lift force map. Furthermore, it is not necessary to use the remaining arm angle θ _A , bucket angle θ _B , and hoist cylinder force F as input parameters.

Figure 10 illustrates the target pulling force map M4~M6 used for calculating a target traction force depending only on the arm angle theta _A. Each map M4~M6, the more are the target traction force is set to increase, gradually arm 5 is raised in terms of allowed reliably perform lifting drilling operations residue thus when the arm angle theta _A decreases In general, the traction force can be increased and the working efficiency is improved. When using this map is replaced with the process of the step S3 shown in FIG. 7 reads the target pulling force map, only the calculation of the arm angle theta _A step S4 is performed, the target pulling force map that is read in step S5 is referred Thus, the target traction force is calculated based on the arm angle θ _A calculated in step S4.

  The controller 30 may store only one target traction force map and always refer to the map, or may store a plurality of target traction force maps. When a plurality of maps are stored, it is preferable that the operator can instruct the map referred to by the controller 30 with the changeover switch 23. As a result, in the same manner as described above, for example, optimum traction force and lift force can be applied according to the type of excavation object.

  FIG. 11 shows an example in which the target rotational speed is calculated by referring to the target rotational force map in accordance with the target traction force after calculating the target traction force with reference to the target lift force map or the target traction force map. The modification of a map is shown. In the embodiment shown in FIG. 6, one target rotation speed map is set for a certain speed ratio. However, as shown in FIG. 11, a plurality of target rotation speeds for a certain speed ratio is set. A map may be set. In other words, a plurality of map patterns for setting different target rotational speeds depending on the speed ratio as shown in FIG. 6 may be stored.

  At this time, even if the operator can instruct which of the plurality of target rotational speed map patterns is to be used to calculate the target rotational speed by operating the changeover switch 24 in the cabin 17. Good.

  In such a configuration, an input signal from the changeover switch 24 is input to the controller 30 in step S1, and a target rotation speed map pattern to be referred to is selected based on the input signal in step S3. In step S6, by referring to the selected pattern, the target rotational speed is calculated based on the speed ratio and the target traction force calculated in step S5.

In addition, as described above, the target traction force can be calculated without calculating the target lift force using the arm angle θ _A , bucket angle θ _B and hoist cylinder force F as input parameters. It is also possible to directly calculate the target rotational speed without calculating the target traction force as an input parameter. That is, the controller 30 may store in advance the target rotational speed map for calculating the target rotational speed in accordance with the arm angle θ _A , bucket angle θ _B , hoist cylinder force F, and speed ratio. At this time, it is not necessary to store the target lift force map and the target traction force map.

Further, it is not necessary to use all of the arm angle θ _A , bucket angle θ _B , hoist cylinder force F, and speed ratio as input parameters. For example, as described above, the speed ratio generally falls within a numerical range of 0 to 0.4 during excavation work, and within this range, the maximum absorption torque of the torque converter 11 for a certain rotational speed does not change significantly. (See torque curves TT1 to TT5 in FIG. 6). For this reason, although the accuracy of the control for applying the target traction force is improved by determining a different target rotation speed according to the speed ratio, the target traction force and the target traction force can be determined regardless of the speed ratio. It is considered that there is no big difference with the actual traction force. Therefore, priority can be given to reducing the load on the controller, and the speed ratio can be appropriately omitted from the input parameters of the target rotational speed map.

Therefore, as shown in FIG. 12, the target rotational speed maps M7 to M9 may be set so that the target rotational speed is calculated only in accordance with the arm angle θ _A , like the target traction force map. At this time, by setting so that the target rotational speed increases as the arm angle θ _A decreases, in general, the excavation work is reliably lifted and the arm 5 is generally raised. The traction force can be increased and work efficiency is improved. When such a map is used, step S3 shown in FIG. 7 is replaced with a process of reading the target rotational speed map. In step S4, only the calculation of the arm angle θ _A is performed, step S5 is omitted, and step S6 is performed. Then, by referring to the read target rotational speed map, the target rotational speed is calculated based on the arm angle θ _A calculated in step S4.

  Further, the controller 30 may store only one target rotation speed map and always refer to the map, or may store a plurality of target rotation speed maps. When a plurality of maps are stored, it is preferable that the operator can instruct the map referred to by the controller 30 with the changeover switch 23.

  Although the wheel loader has been illustrated as an industrial vehicle in the above, the present invention is an industry for excavating, transporting and loading work such as a crawler loader, a load hole dumper, a bulldozer, a scraper, and a hydraulic excavator. It can be widely applied to industrial vehicles.

  INDUSTRIAL APPLICABILITY The present invention has an effect that the traction force and the lift force are finely adjusted according to the handling posture of the arm and the bucket and the working efficiency is improved. For example, the present invention is beneficial when applied to a wheel loader or the like.

DESCRIPTION OF SYMBOLS 1 Wheel loader 2 Car body 5 Arm 6 Bucket 7 Hoist cylinder 9 Bucket cylinder 10 Prime mover 11 Torque converter 16 Hydraulic pump 23, 24 change-over switch 30 Controller 37 Carrying attitude detector 42 Prime mover control module F _T traction force F _L Lift force F Hoist cylinder Power

Claims (7)

An arm and a bucket that are swingably attached to the vehicle body and for excavating and lifting an object to be excavated;
An actuator that applies a driving force to the arm and the bucket and generates a lift force that acts on the object to be excavated from the bucket;
A control device for calculating a target traction force acting on the vehicle body in accordance with the handling posture of the arm and bucket;
A motor that is controlled by the control device and generates the target traction force ;
Said controller, industrial vehicle handling posture of said arm, characterized that you calculate the target pulling force increases closer horizontally. The actuator includes a hoist cylinder that swings the arm, and a bucket cylinder that swings the bucket,
The industrial vehicle according to claim 1, wherein the control device detects the cargo handling posture based on an angle of the arm with respect to the vehicle body or an extension amount of the hoist cylinder. The industrial vehicle according to claim 2 , wherein the control device further detects the cargo handling posture based on an angle of the bucket with respect to the vehicle body or an extension amount of the bucket cylinder.   The industrial vehicle according to claim 1, wherein the control device further calculates a target traction force acting on the vehicle body according to a driving force applied to at least the arm and the bucket by the actuator. An arm and a bucket that are swingably attached to the vehicle body and for excavating and lifting an object to be excavated;
An actuator that applies a driving force to the arm and the bucket and generates a lift force that acts on the object to be excavated from the bucket;
A control device for calculating a target traction force acting on the vehicle body in accordance with the handling posture of the arm and bucket;
A prime mover controlled by the control device to generate the target traction force;
A target lift force map storage unit for storing a plurality of target lift force maps indicating the relationship between the cargo handling posture and the target lift force;
A lift force command device for receiving an input of a target lift map command to be selected from an operator;
The control device selects one of the plurality of target lift force maps in response to a command from the lift force commander among the plurality of stored target lift force maps, and the selected target lift force map industrial vehicle we calculate the target lift force by referring to a map. An arm and a bucket that are swingably attached to the vehicle body and for excavating and lifting an object to be excavated;
An actuator that applies a driving force to the arm and the bucket and generates a lift force that acts on the object to be excavated from the bucket;
A control device for calculating a target traction force acting on the vehicle body in accordance with the handling posture of the arm and bucket;
A prime mover controlled by the control device to generate the target traction force;
A target rotation speed map storage unit for storing a plurality of target rotation speed maps for calculating the target traction force and the target rotation speed of the prime mover necessary for generating the target traction force;
And a torque converter connected to the prime mover,
The control device selects one of the plurality of target rotational speed maps according to a ratio between the rotational speed of the input shaft of the torque converter and the rotational speed of the output shaft of the torque converter, and the selected target industrial vehicles with reference to the rotational speed map you calculate the target rotational speed. The control device determines whether or not an excavation work is being performed on the object to be excavated by the arm and the bucket, and when determining that the excavation operation is being performed, the control device determines the loading posture of the arm and the bucket. The industrial vehicle according to any one of claims 1 to 6 , wherein control of the prime mover is executed.

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