JP7228493B2 - construction machinery - Google Patents

Description

The present invention relates to an angle sensor mounting structure for construction machinery.

Wheel loaders mainly scoop up minerals and sand piled up on the ground and load them onto dump trucks. When the wheel loader scoops up the earth and sand, the bucket attached to the tip of the wheel loader is tilted forward at a height that is slightly raised from the ground, and the wheel loader is advanced to hit the earth and sand near the ground, and the vehicle speed increases. Make the bucket bite into the earth and sand using inertia. Next, by manipulating the length of the bucket cylinder that adjusts the angle of the bucket and the arm cylinder that adjusts the height of the bucket, the angle of the bucket is raised and the height of the bucket is raised to scoop up the earth and sand. Then, the scooped up earth and sand are dumped onto the loading platform of the dump truck.

In order to perform such a series of loading operations of the wheel loader, the wheel loader has an arm rotatably attached to the vehicle body and a bucket rotatably attached to the arm. In order to control the position and angle of the bucket during the loading operation, an angle sensor detects the rotation angle of the movable parts that make up the wheel loader, such as the bucket and arm, and the controller performs the required processing based on the detection results. are doing.

The sensor shaft of the angle sensor is connected to the movable member to be detected via an arm functioning as a transmission member, and outputs a voltage corresponding to the rotation angle by rotating together with the movable member to be detected. As a conventional technique, in order to accurately detect the rotation angle, a technique is known in which an angle sensor is attached on the axis of the connecting shaft that supports the rotation of the movable member to be detected, thereby obtaining the angle of the movable member. (See Patent Document 1, for example).

JP 2004-279047 A

However, in the mounting structure of the angle sensor described in Patent Document 1, since the sensor shaft of the angle sensor is rigidly connected to the movable member to be detected via the arm portion, there is a problem that failure may occur due to vibration. . For example, when applied to a wheel loader, each member vibrates due to the movement of the bucket digging into the earth and sand using the inertia of the vehicle body. When the arm portion of the angle sensor vibrates, the portion between the resistor and the electrode inside the angle sensor vibrates and wears out, causing an error in the detected voltage.

If the acquired angle contains an error, the controller of the wheel loader cannot perform the required control. For example, when controlling the angle of the bucket of the wheel loader, it tilts forward more than it should and spills earth and sand. it will cause problems. A failure of the angle sensor is defined as a state in which the angle sensor cannot accurately obtain the angle to be detected as described above and causes a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and its object is to avoid the situation in which the vibration generated in the vehicle body during operation is transmitted to the angle sensor via the transmission member. It is therefore an object of the present invention to provide a construction machine capable of preventing failure of the angle sensor due to vibration.

In order to achieve the above object, the construction machine of the present invention connects a first member and a second member so as to be relatively rotatable about a connecting shaft, and fixes a sensor main body to the first member. and an angle sensor formed by arranging the sensor shaft of the sensor main body on the axis of the connecting shaft, fixing one end of the transmission member, and connecting the other end of the transmission member to the second member. In the construction machine, the first engaging portion formed at the other end of the transmission member and the second engaging portion formed at the second member are arranged radially about the axis of the connecting shaft. and the circumferential direction, the first engaging portion is an engaging hole formed in the other end of the transmission member, and the second engaging portion is the an engaging pin erected on a second member and inserted into the engaging hole, wherein a predetermined amount of backlash is formed between the engaging hole and the engaging pin; A space is provided between the hole and the engaging pin .

According to the construction machine of the present invention, it is possible to avoid a situation in which the vibration generated in the vehicle body during operation is transmitted to the angle sensor via the transmission member, thereby preventing failure of the angle sensor due to the vibration. can be done.

It is a side view showing a wheel loader of an embodiment. FIG. 2 is a detailed view of part A in FIG. 1 showing the angle sensor of the first embodiment; FIG. 3 is a view in the direction of arrow B in FIG. 2 showing an angle sensor; FIG. 5 is a diagram showing changes in attitude of the wheel loader 1 when the bucket is moved from the lowest point to the highest point, and corresponding changes in the angle of the arm of the angle sensor. FIG. 10 is a characteristic diagram comparing a setting example of an initial angle A1=10° and a setting example of an initial angle A1=50°. FIG. 3 is a detailed view corresponding to FIG. 2 showing the angle sensor of the second embodiment;

An embodiment in which the present invention is embodied in a wheel loader will be described below.
FIG. 1 is a side view showing the wheel loader of this embodiment.
The wheel loader 1 includes a front vehicle body 1a having a bucket 3, a bell crank 4 (second member), a bucket cylinder 5, an arm 6 (first member), an arm cylinder 7, front tires 8, an angle sensor 12, and the like. , a driver's cab 2, an engine room 10, and a rear vehicle body 1b having rear wheel tires 9 and the like. The arm 6 is attached to the front vehicle body 1a so as to be vertically rotatable. The bucket 3 is attached to the tip of the arm 6 so as to be vertically rotatable with respect to the arm 6 , and is rotatably driven through the bell crank 4 by the expansion and contraction of the bucket cylinder 5 .

[First embodiment]
2 is a detailed view of part A in FIG. 1 showing the angle sensor of the first embodiment, and FIG. 3 is a view of the angle sensor as viewed from arrow B in FIG.
The bellcrank 4 is connected to a bracket 6a provided on the arm 6 by a connecting shaft 13 so as to be relatively rotatable, and the sensor body 14 of the angle sensor 12 is fixed on the bracket 6a. A sensor shaft 15 protrudes laterally from the sensor main body 14 along the axis C of the connecting shaft 13 , and one end of an arm portion 16 (transmission member) bent into a crank shape is fixed to the sensor shaft 15 . there is The other end of the arm portion 16 is overlapped on the bellcrank 4 and has a circular engagement hole 17 (first engagement portion) penetrating therethrough. An engaging pin 18 (second engaging portion) having a rounded cross section is inserted. The outer diameter of the engaging pin 18 is set smaller than the inner diameter of the engaging hole 17 , so that a predetermined amount of backlash (play) is formed around the engaging pin 18 in the engaging hole 17 . Due to this backlash, the engaging hole 17 and the engaging pin 18 are relatively displaceable within a plane including the radial direction and the circumferential direction about the axis C of the connecting shaft 13 .

The amount of backlash is set to a value larger than the amount of relative displacement due to vibration between the bellcrank 4 and the arm 6 caused by the loading operation of the wheel loader 1, for example 10 mm. When the bellcrank 4 rotates about the axis C of the connecting shaft 13 with respect to the arm 6, the rotation is transmitted from the engaging pin 18 to the arm portion 16, and the sensor shaft 15 is aligned via the arm portion 16. It rotates in a direction and an angle, and a voltage corresponding to the rotation angle is output from the sensor main body 14 .

Since a predetermined amount of backlash is provided between the engaging hole 17 of the arm portion 16 and the engaging pin 18 in this manner, the amount of backlash between the bellcrank 4 and the arm 6 is less than or equal to the predetermined amount. Even if a relative vibration of amplitude occurs, the vibration is contained within the backlash of the arm portion 16 and is absorbed. Vibration occurs in various directions, but since the engaging hole 17 and the engaging pin 18 are separated from each other, the vibration in any direction is absorbed by the backlash. Therefore, it is possible to avoid a situation in which vibration is transmitted to the arm portion 16, and it is possible to prevent failure of the angle sensor 12 caused by the vibration.

FIG. 4 shows a state in which the bucket 3 is tilted to the front most near the ground (hereinafter referred to as the lowest point), the arm cylinder 7 is fully extended, and the bucket 3 is tilted to the rearmost position (hereinafter referred to as the highest point). 2 is a diagram showing a posture change of the wheel loader 1 and a corresponding angle change of the arm portion 16 of the angle sensor 12 when the wheel loader 1 is set to . In FIG. 2, the arm portion 16 at the lowest point is indicated by a solid line, and the arm portion 16 when moving from the lowest point to the highest point is indicated by a broken line.

As shown by the solid line in FIG. 4, at the lowest point, the bucket 3 is tilted to the front most near the ground surface, and as shown in FIG. An angle A (hereinafter referred to as initial angle A1) formed by L1 (hereinafter abbreviated as pin angle line L1) and a vertical line L2 (hereinafter abbreviated as vertical line L2) passing through axis C of sensor shaft 15 is, for example, 10 °. From this posture, the angle A formed by the pin angle line L1 and the vertical line L2 increases regardless of whether the bucket cylinder 5 or the arm cylinder 7 is operated. When the arm cylinder 7 is operated to the extension side to the maximum, the positions of the arm 6, the bucket 3, and the bell crank 4 are changed by the arrow indicated by the lift operation in the figure, and the sensor shaft 15 is also rotated. Further, when the bucket cylinder 5 is operated to the maximum to tilt forward, the position changes by the amount of the arrow indicated by the bucket operation, and the posture of the wheel loader 1 changes to the highest point. At this time, the angle A formed by the pin angle line L1 and the vertical line L2 (hereinafter referred to as the final angle A2) is, for example, 160°.

As a result, the rotation range of the engagement pin 18 from the lowest point to the highest point (in other words, the rotation angle of the bellcrank 4 with respect to the arm) is 150°, and within this rotation range the engagement pin 18 is vertical. It is kept at a position not exceeding the line L2. As will be described later, in order for the play not to affect the detected value of the rotation angle, the engagement pin 18 must always be in contact with the same portion of the engagement hole 17 during rotation. In other words, it is necessary to design the link mechanism of the bellcrank 4 so that the rotation range does not exceed the vertical line L2, or invalidate the detected value after exceeding the vertical line L2.

As shown in FIG. 2, the rotation direction of the arm portion 16 due to gravity is always counterclockwise when it is on the left side of the vertical line L2 in the drawing. Therefore, in the range where the attitude of the wheel loader 1 changes from the lowest point to the highest point shown in FIG. 4, as indicated by the solid and broken lines in FIG. direction, it remains in contact with the engagement pin 18 under the action of gravity.

FIG. 5 is a characteristic diagram comparing the setting example of the initial angle A1=10° and the setting example of the initial angle A1=50°. The horizontal axis is the angle A between the pin angle line L1 and the vertical line L2. , and the vertical axis is the angle θ detected by the angle sensor 12 .
In the case of the initial angle A1=10° indicated by the solid line, the arm portion 16 of the angle sensor 12 is constantly in contact with the engaging pin 18 under the action of gravity in the counterclockwise direction, thereby causing the engaging pin 18 to rotate. The engagement pin 18 and the arm portion 16 are kept in the same positional relationship within the range (10 to 160°). Therefore, an accurate detection angle θ corresponding to the angle A formed by the pin angle line L1 and the vertical line L2 is obtained.

On the other hand, when the initial angle A1=50° indicated by the dashed line, the direction of gravity acting on the arm portion 16 is clockwise when the engaging pin 18 crosses the vertical line L2 (A=180°). Flip. As a result, the positional relationship between the engaging pin 18 and the arm portion 16 changes as indicated by the phantom lines in FIG. , the arm portion 16 rotates separately. In FIG. 5, since the rotation of the arm portion 16 corresponding to the looseness is illustrated as 2°, +2° in the region from the time when the engaging pin 18 crosses the vertical line L2 until it reaches the final angle A2. , for example, the final angle A2=200° is detected as the detected angle θ=202°. Originally, the link mechanism of the bellcrank 4 should be designed so that the range of rotation does not exceed the vertical line L2. can be difficult to design. Therefore, in this embodiment, the output of the sensor detected angle after the engagement pin 18 crosses the vertical line L2 is invalidated.

In this embodiment, a discontinuous change in the sensor detection angle that occurs when the engagement pin 18 crosses the vertical line L2 (A=180°) in FIG. Disable. Specifically, the angle sensor uses, for example, a photoelectric element, and the detection signal of the sensor element is processed by a signal processor built into the sensor and output, so that discontinuous changes in the detected value can be detected. It is possible to If the output signal after detecting this discontinuous change is invalidated by the signal processor, as a result, an accurate detection angle θ corresponding to the angle A formed by the pin angle line L1 and the vertical line L2 can be obtained. It is possible to realize a high detection accuracy of the rotation angle. Also, external signal processing means may be connected separately from the signal processor to detect and invalidate discontinuous changes in the detected angle signal. A discontinuous change in the detected angle signal may occur repeatedly each time the bucket rotates. It indicates that the sensor has returned to the measurement target area, and it is also possible to switch between enabling/disabling of the detection angle signal output each time a discontinuous change is detected.
On the other hand, by forming backlash around the engaging pin 18 in the engaging hole 17, another effect is obtained in that the mounting operation of the angle sensor 12 can be easily carried out.

[Second embodiment]
FIG. 6 is a detailed view corresponding to FIG. 2 showing the angle sensor 12 of the second embodiment.
In contrast to the first embodiment that utilizes gravity, this embodiment utilizes the biasing force of the compression spring 21 to maintain the same positional relationship between the engaging pin 18 and the arm portion 16 . As shown by solid lines in FIG. 6, the engaging hole 22 (first engaging portion) of the present embodiment has a square shape, and a predetermined amount of backlash is formed around the engaging pin 18 in the engaging hole 22. It is Centering on the axis C of the sensor shaft 15, the engaging pin 18 is arranged on the clockwise side (left side in the drawing) in the engaging hole 22, and the counterclockwise side in the engaging hole 22 ( A compression spring 21 is arranged on the right side). As a result, the arm portion 16 of the angle sensor 12 is always subjected to the biasing force of the compression spring 21 in the counterclockwise direction.
The direction in which the arm portion 16 is biased by the compression spring 21 is not limited to the counterclockwise direction. Therefore, the biasing force of the compression spring 21 may be applied clockwise.

The biasing force of the compression spring 21 is strong enough to bend when subjected to vibration generated between the bellcrank 4 and the arm 6 and to restrict the movement of the engagement pin 18 within the engagement hole 22. is set. Therefore, the vibration generated between the bellcrank 4 and the arm 6 is absorbed inside the backlash of the arm portion 16 while the compression spring 21 is deflected. As a result, it is possible to avoid a situation in which vibration is transmitted to the arm portion 16, and to prevent failure of the angle sensor 12 due to the vibration.

On the other hand, in this embodiment, the initial angle A1 is 10 degrees, which is the same as in the first embodiment, but the final angle A2 is set at 200 degrees. Therefore, as described with reference to FIG. 5, when the engaging pin 18 crosses the vertical line L2, the direction of gravity acting on the arm portion 16 is reversed clockwise. However, since the compression spring 21 continues to apply the biasing force in the counterclockwise direction, the engagement pin 18 and the arm portion 16 maintain the same positional relationship within the entire rotation range of the engagement pin 18 up to the final angle A2. be kept. As a result, in this embodiment, by using the biasing force of the compression spring 21, the pin angle line L1 and the vertical line can be obtained without being affected by the backlash between the engagement pin 18 and the engagement hole 22 of the arm portion 16. An accurate detection angle .theta. corresponding to the angle A formed with the line L2 can be obtained, and excellent detection accuracy of the rotation angle can be achieved.

Although the description of the embodiment is finished above, the aspect of the present invention is not limited to this embodiment. For example, in the above-described embodiment, the angle sensor detects the rotation angle of the bell crank 4 with respect to the arm 6 of the wheel loader 1. However, it may be embodied as an angle sensor that detects the rotation angle of the arm 6 with respect to the front vehicle body 1a. It may also be applied to other construction machines.

In the above embodiment, the engagement hole 17 is formed in the other end of the arm portion 16 as the first engagement portion, and the engagement pin 18 is erected on the bell crank 4 as the second engagement portion. Both may be reversed, or the engaging portions may have other shapes that form play between them. Alternatively, for example, the engagement pin 18 may be formed integrally with the bell crank 4 .

1 Wheel loader (construction machinery)
4 bellcrank (second member)
6 Arm (first member)
12 angle sensor 13 connecting shaft 15 sensor shaft 16 arm portion (transmission member)
17, 22 engagement hole (first engagement portion)
18 engagement pin (second engagement portion)
21 compression spring

Claims (5)

A first member and a second member are connected so as to be relatively rotatable about a connecting shaft, a sensor main body is fixed to the first member, and a sensor shaft of the sensor main body is aligned on the axis of the connecting shaft. is disposed to fix one end of the transmission member, and the other end of the transmission member is connected to the second member,
A first engaging portion formed at the other end of the transmission member and a second engaging portion formed at the second member extend radially and circumferentially around the axis of the connecting shaft. formed to be relatively displaceable within a plane containing
the first engaging portion is an engaging hole formed at the other end of the transmission member;
The second engaging portion is an engaging pin erected on the second member and inserted into the engaging hole,
A predetermined amount of backlash is formed between the engagement hole and the engagement pin to separate the engagement hole and the engagement pin.
A construction machine characterized by: The outer diameter of the engaging pin is smaller than the inner diameter of the engaging hole, and the backlash is formed in the engaging hole.
The construction machine according to claim 1, characterized in that: The first member and the second member have a rotational range of less than 180° about the connecting shaft,
2. The method according to claim 1 , wherein the engaging pin is kept at a position not exceeding a vertical line passing through the axis of the sensor shaft within the rotation range of the first member and the second member. Construction equipment as described. A compression spring is disposed in the engagement hole together with the engagement pin,
2. The construction machine according to claim 1 , wherein said transmission member is biased in a circumferential direction around the axis of said sensor shaft by said compression spring. 2. The construction machine according to claim 1 , wherein said angle sensor includes signal processing means for detecting a discontinuous change in the detected angle and nullifying an output signal after detecting said discontinuous change.

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