JPH0786326B2 - Belt tension automatic adjustment device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a belt tension automatic adjusting device for automatically adjusting the tension of a belt such as a timing belt of an internal combustion engine.

(Prior art and its problems) Belt tension of a timing belt or the like of an internal combustion engine is an important quality control item because the belt tension is closely related to noise and vibration of the internal combustion engine, and further, the durability of the belt, In the manufacturing process of an internal combustion engine, the belt tension is adjusted to a predetermined value.

Conventionally, the belt tension is adjusted by the operator's hand feeling while the internal combustion engine is stopped. However, there are variations in the circumference of the attached belt,
Therefore, the tensioner spring pressure also fluctuates, and it is difficult to accurately grasp the belt tension that changes for each engine stop crank angle position in relation to the engine stop crank angle position. The belt tension cannot be accurately adjusted to the above-mentioned predetermined value by adjusting the belt tension by the method, and therefore quality control is difficult.

The present invention has been made to solve such problems, and does not rely on the feel of a worker to adjust the tension of the belt,
An object of the present invention is to provide an automatic belt tension adjusting device that can be adjusted accurately in a short time.

(Means for Solving the Problems) In order to achieve the above-mentioned object, a belt tension automatic adjusting device of the present invention is a belt that presses an endless belt that is wound between a driving wheel and a driven wheel of an internal combustion engine. A roller that rotates in response to the rotation of the tensioner that keeps the tension constant, and that presses the tensioner to change the belt pressing force of the tensioner; and the internal combustion engine that moves the roller forward and backward with respect to the tensioner. Roller driving means separate from
A load detecting means for detecting the tensioner pushing load of the roller, and a drive signal corresponding to an initial pushing amount preset to the driving means are outputted, and the tensioner pushing load of the roller detected by the load detecting means is stored in advance. The amount of pushing of the roller is calculated according to the target pushing load, a driving signal is output to the roller driving means according to the calculated value, and the amount of pushing is adjusted at the completion of a preset number of times. Control means for setting the initial pushing amount, and adjusting the tension of the endless belt while rotationally driving the internal combustion engine.

(Operation) In order to adjust the belt tension according to the detected value of the roller tensioner pushing load and the detected pushing load while the engine is rotating, it is necessary to relate to the variation of the belt circumference and the engine crank angle position. It is possible to adjust the belt tension to a predetermined value without the need.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the entire structure of an automatic belt tension adjusting device according to the present invention.
It is applied to the tension adjustment of the timing belt of the 6-cylinder engine 1.

The toothed timing belt 2 of the engine 1 includes a cam sprocket 3 attached to the cam shaft of the left bank 1a, and a water pump attached to the drive shaft of the water pump arranged above the cylinder block between the left and right banks 1a and 1b. The pulley 5, the cam sprocket 4 attached to the camshaft of the right bank 1b, the crank sprocket 6 attached to the crankshaft, and the tensioner 8 are sequentially wound around, and the rotation of the crankshaft drives the camshafts and water pumps of the left and right banks. Transmit to the shaft.

The tensioner 8 is on the loose side of the timing belt 2,
That is, it is arranged between the crank sprocket 6 and the cam sprocket 3 (the engine 1 is rotationally driven in the direction shown by the arrow in FIG. 1). The tensioner 8 is rotatably attached to a bracket 8b by a tensioner bolt 8a. The bracket 8b is capable of swinging the tensioner 8 in a direction orthogonal to the timing belt 2 around a support shaft (not shown) and a tensioner spring 8c. The tensioner 8 is attached and constantly presses the timing belt 2 with a predetermined pressing force by the spring force of the tensioner spring 8c.

The belt tension automatic adjusting device 10 according to the present invention includes a housing.
10a, a pair of rollers (cam followers) 11 and 11 that are in sliding contact with the tensioner 8 and rotate together with the tensioner 8, a support 12 that rotatably supports the roller 11 at one end, and a guide (not shown) inside the housing 10a. A base body 14 which moves along a rail and on which the other end portion 12b of the support body 12 is fixedly mounted,
It is configured to include a pulse motor 15 and a control device 20.

The drive shaft of the pulse motor 15 and the base body 14 are connected via a ball screw 16, and the ball screw 16 converts the rotational movement of the pulse motor 15 into a translational movement of the base body 14. This allows
As will be described later in detail, the base 14 moves together with the support 12 to press the roller 11 against the tensioner 8, and the belt tension is adjusted according to the moving amount of the base 14, that is, the pushing amount of the roller 11.

The tensioner pushing load of the roller 11 is detected by the load cell 13 formed of, for example, a strain gauge.
Is attached near the other end 12a of the support 12.
The load cell 13 is electrically connected to the input side of the control device 20. The control device 20 includes an amplifier for amplifying the voltage waveform from the load cell 13, calculation of the pushing amount of the roller 11, and a pulse motor.
A central processing unit (CPU) that controls the drive of 15 etc., a sequence for controlling the output timing of the drive signal to the pulse motor 15, an output period, etc., a control program executed by the central processing unit, an initial used for various calculations It is composed of a storage device that stores values and the like (none of which are shown), a drive circuit 20a that outputs a drive signal to the pulse motor 15, and the like. As will be described later in detail, the control device 20 detects the load cell 13 A drive signal for rotating the pulse motor 15 in the normal or reverse direction is supplied to the pulse motor 15 according to the tensioner pushing load of the roller 11 and the target pushing load.

The operation of the belt tension automatic adjusting device 10 configured as described above will be described with reference to FIGS. 2 and 3.

The central processing unit of the control device 20 drives the pulse motor 15 according to the procedure shown in the flowchart of the belt tension adjusting program shown in FIG. 2 to automatically adjust the tension of the timing belt 2. More specifically, the engine 1 is attached to an adjustment stand (not shown), and the belt tension automatic adjusting device 10 is set at a predetermined position. At this time, the tensioner bolt 8a of the tensioner 8 is loosened so that the tensioner 8 can move relative to the bracket 8b. Further, the tensioner spring 8c is removed from the bracket 8b, and the tensioner 8 is fixed to the timing belt 8 by the roller 11.
It is pressed by and is sandwiched between the timing belt 8 and the roller 11 of the belt tension automatic adjusting device 10.

When the belt tension automatic adjusting device 10 is operated in this state,
The control device 20 first executes step S1 of the program shown in FIG. 2 to calculate and set an initial pushing amount by the roller 11 described later. The calculation of the initial pushing amount is performed by averaging the pushing amounts at the time of completion of adjustment, which are stored in the belt tension automatic adjusting device 10 when the belt is adjusted a predetermined number of times (for example, 10 times) before the present adjustment and It is a quantity. By calculating and setting the initial pushing amount in this way, even if the timing belts 8 of different lots are used, the optimum initial pushing amount can be learned and set for each lot. The push-in amount can be corrected a minimum number of times, which is effective in reducing the cycle time required for adjusting the tension of the timing belt of one engine.

Next, the engine 1 is rotationally driven at a predetermined rotational speed to start a familiar operation (step S3). Normally, the timing belt 2 and the cam sprocket 3, at the beginning of rotation of the engine 1,
Since the tooth surface is familiar with 4 etc., the belt tension usually decreases significantly. Therefore, familiar operation for a predetermined time (for example, about 4 to 5 seconds) is required. Also, the above-mentioned predetermined number of revolutions can be set to an appropriate value, but if the number of revolutions is too low, the adjustment time (cycle time) will be too long, for example 100 rpm.
It is set to a degree.

During this familiar operation, the driving of the pulse motor 15 is started (time t1 in FIG. 3 (c)), and the roller 11 is moved to the step S1.
The timing belt 2 is advanced by the initial push-in amount set in step 3 to apply initial tension to the timing belt 2 (step S5). The diagram shown in FIG. 3 (a) shows the change over time in the belt pushing load value L _C of the roller 11 detected by the load cell 13,
FIG. 3B is a time change of the average value L _CAV of the pushing load values L _C detected by the load cell 13 while the crankshaft of the engine 1 makes two revolutions.

Next, it is determined whether or not the familiar operation of the engine 1 is completed (step S7), and if it is not completed yet, the operation waits until the familiar operation is completed. By the time t2 when the familiar operation of the engine 1 is completed, the indentation load average value L _CAV detected by the load cell 13 is settled as shown in FIG. 3 (b). Therefore, when the familiar driving is completed (when the determination result of step S7 is affirmative (Yes)), the control device 20 starts reading the pushing load value L _C of the roller 11 detected by the load cell 13 (first At time t2 in FIG. 3 (c), when the crankshaft of the engine 1 makes two revolutions (at the same figure)
At the time of t3), the reading ends, and the average value L _CAV of the pushing load values L _C read during this period is calculated (step S9). Since the engine 1 is a V-type 6-cylinder engine, the peak value of the load signal value L _C of the load cell 13 appears three times while the crankshaft makes two revolutions corresponding to the valve opening / closing timing of the valve operating mechanism. By averaging the load signal values L _C detected during this period, a pushing load with a small time change can be obtained.
Then, the deviation between the calculated indentation load average value L _CAV and the target load Lo is obtained, and it is determined whether or not the absolute value of this deviation is smaller than a predetermined value ΔL (at time t4 and second time in FIG. 3 (c)). Step S11 in the figure).

If the determination result in step S11 is negative (No), the pushing amount of the roll 11 is feedback-corrected according to the above deviation (step S13). Various methods can be considered as a method of correcting the pushing amount, but the positive / negative of the deviation and the predetermined value Δ
The correction value of the pushing amount may be determined according to the difference from L or the like. The control device 20 outputs a drive signal to the pulse motor 15 according to the calculated correction value of the pushing amount to change the belt pushing load of the roller 11 to adjust the belt tension of the timing belt 2. Then, when the correction of the pushing amount of the roller 11 is completed (time t6 and time t9 in FIG. 3 (c)), the process returns to the step S9 again and the step S9 is repeated until the determination result in the step S11 becomes affirmative. Execute S11 and S13.

When the determination result in step S11 is affirmative (at time t10 in FIG. 3C), the control device 20 causes the timing belt 2
On the assumption that the tension adjustment of (1) is completed, the pushing amount of the roller 11 at the time of completion of the tension adjustment is stored in the storage device (step S15). As described above, this stored value is used in step S1 to set the initial pushing amount when adjusting the timing belt tension, which is executed thereafter. Next, the worker stops the engine 1 (step S17), tightens the tensioner bolt 8a in step S19 to fix the axial support position of the tensioner 8 with respect to the bracket 8b, and further the bracket 8b.
Attach the tensioner spring 8c to and finish the timing belt tension adjustment.

After the adjustment of the tension of the timing belt, the belt tension in the stationary state of the engine is measured by the free vibration method or the conventionally known Borrows tensiometer method after the adjustment to measure the variation of the belt tension for each engine. The free vibration method is to vibrate the belt on the tension side (between cam sprocket 3 and water pump pulley 5 and between cam sprocket 4 and crank sprocket 6) and loose side (between tensioner 8 and cam sprocket 3) of the timing belt, and Is detected by an FFT analyzer and averaged to find the belt tension.
This method is preferable because the measurement error is smaller than the belt tension obtained by the conventionally known Borrows tensiometer method. When the variations of the tension of the timing belt when the engine is stationary measured in this way are compared for each engine, the belt adjusted by the device of the present invention is different for each engine as compared with the one adjusted by the conventional hand feeling. The result was that the variation in belt tension was extremely small.

In the above-mentioned embodiment, the belt tension automatic adjusting device of the present invention is applied to the belt tension adjustment of the timing belt, but the present invention is not limited to this. A drive shaft for driving a crank sprocket, an alternator and an air conditioner compressor. It can also be applied to adjust the belt tension of an endless belt hung between the sprockets attached to the.

(Effects of the Invention) As described in detail above, according to the belt tension automatic adjusting apparatus of the present invention, the belt tension is kept constant by pressing the endless belt that is wound between the driving wheel and the driven wheel of the internal combustion engine. A roller that rotates in response to the rotation of the tensioner and that presses the tensioner to change the belt pressing force of the tensioner,
A roller driving means separate from the internal combustion engine for moving the roller forward and backward with respect to the tensioner, a load detecting means for detecting a tensioner pushing load of the roller, and an initial pushing amount preset in the driving means. A corresponding drive signal is output, the pushing amount of the roller is calculated according to the roller tensioner pushing load detected by the load detecting means and the target pushing load stored in advance, and the roller driving means is calculated according to the calculated value. While outputting the drive signal,
A control means for setting the initial pushing amount according to the pushing amount at the completion of the preset number of adjustments is configured, and the tension of the endless belt is adjusted while the internal combustion engine is rotationally driven. The belt tension can be adjusted to a predetermined value accurately and in a short time without depending on the hand feeling of the operator.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is an overall configuration diagram of a belt tension automatic adjusting device according to the present invention, and FIG. 2 is a flowchart showing a procedure for adjusting belt tension by the belt tension automatic adjusting device, FIG. 3 shows the time change of the pushing load L _C of the roller 11 detected by the load cell 13 of the automatic belt tension adjusting device shown in FIG. 1, the time change of the same pushing load average value L _CAV , and the measurement of the pushing load L _C. It is a graph which shows the relationship of timing. 1 ... Internal combustion engine, 2 ... Timing belt (endless belt), 3,4 ... Cam sprocket (driven wheel), 6 ...
… Crank sprocket (driving wheel), 8 …… tensioner, 8a …… tensioner bolt, 8c …… tensioner spring, 10 …… automatic belt tension adjusting device, 11 …… roller,
13 ... Load cell (load detection means), 15 ... Pulse motor (roller drive means), 20 ... Control device (control means).

Claims (1)

[Claims] Claim: What is claimed is: 1. An endless belt wound between a driving wheel and a driven wheel of an internal combustion engine is pressed to rotate in response to the rotation of a tensioner that keeps the belt tension constant, and the tensioner is pressed. A roller for changing the belt pressing force of the tensioner, and a roller driving means separate from the internal combustion engine for moving the roller forward and backward with respect to the tensioner,
A load detecting means for detecting the tensioner pushing load of the roller, and a drive signal corresponding to an initial pushing amount preset to the driving means are outputted, and the tensioner pushing load of the roller detected by the load detecting means is stored in advance. The amount of pushing of the roller is calculated according to the target pushing load, a driving signal is output to the roller driving means according to the calculated value, and the amount of pushing is adjusted at the completion of a preset number of times. And a control means for setting the initial pushing amount and adjusting the tension of the endless belt while rotating the internal combustion engine.