JPH01310125A - Automatic adjusting device for belt tension - Google Patents

Abstract

PURPOSE:To adjust a belt tension in a short time and certainly by providing such a constitution that the push-in amount of a roller is adjusted according to a tensioner push-in load of the roller and a target push-in load while an internal combustion engine is driven in rotation. CONSTITUTION:The driving shaft of a pulse motor 15 is connected to a base body 14 via a ball screw piece 16. The rotational motion of the motor 15 is converted into the translational motion of the base body 14 by the ball screw piece 16. Then, the base body 14 is moved together with a supporting body 12 so as to push a roller 11 onto a tensioner 8, and the tension of a timing belt 2 is adjusted according to the moving amount of the base body 14, namely, the push-in amount of the roller 11. The tensioner push-in load of the roller 11 is detected by a load cell 13 while an internal combustion engine 1 is rotated so as to input this detected value into a control device 20. In the device 20, the push-in amount of the roller 11 is calculated according to this detected value and a target push-in load, and the driving signal is outputted to the motor 15 in response to the calculated value so as to adjust the belt tension.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an automatic belt tension adjustment device that automatically adjusts the tension of a belt such as a timing belt of an internal combustion engine.

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

Conventionally, the belt tension has been adjusted by an operator's touch while the internal combustion engine is stopped.

However, there are variations in the circumferential length of the attached belts, and as a result, the tensioner spring pressure also varies, and it is necessary to accurately grasp the belt tension, which changes depending on the engine's stopped crank angle position, in relation to the engine's stopped crank angle position. For some reasons, it is difficult to adjust the belt tension to the above-mentioned predetermined value by adjusting the belt tension by the operator's touch, and therefore quality control has been difficult.

The present invention has been made in order to solve such problems, and provides an automatic belt tension adjustment device that can accurately adjust belt tension in a short time without tying up the worker's efforts. The purpose is to

(Means for Solving the Problems) In order to achieve the above-mentioned object, the belt tension automatic adjustment device of the present invention presses an endless belt wound between a driving wheel and a driven wheel of an internal combustion engine to a roller that rotates in response to the rotation of a tensioner that maintains a constant tension and presses the tensioner to change the belt pressing force of the tensioner; and a roller driving means that moves the roller forward and backward relative to the tensioner. , a load detection means for detecting a tensioner push-in load of the roller; and a load detection means for calculating the push-in amount of the roller according to the tensioner push-in load of the roller detected by the load detection means and a target push-in load stored in advance; It is characterized by comprising a control means for outputting a drive signal to the roller drive means according to the value, and adjusting the tension of the endless belt while rotationally driving the internal combustion engine.

(Function) In order to detect the tensioner pushing load of the roller while the engine is rotating and adjust the belt tension according to this detected value and the target pushing load, it is necessary to adjust the belt tension according to the variation in belt circumference and the engine crank angle position. This makes it possible to adjust the belt tension to a predetermined value without any trouble.

(Example) An example of the present invention will be described in detail below based on the drawings.

FIG. 1 shows the overall configuration of an automatic belt tension adjustment device according to the present invention, and an automatic heald tension adjustment device 10 of this embodiment is applied to tension adjustment of a timing heald of a type 6 six-cylinder engine 1.

The toothed timing belt 2 of the engine L is on the left bank 1a.
cam sprocket 3 attached to the camshaft of
A water pump pulley 5 is attached to the drive shaft of the water pump located at the top of the cylinder block between the left and right banks la and lb, a cam sprocket 4 is attached to the camshaft of the right bank lb, and a crank is attached to the crankshaft. It is sequentially wound around the sprocket 6 and the tensioner 8, and transmits the rotation of the crankshaft to the left and right bank camshafts and the drive shaft of the water pump.

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

The heald tension automatic adjustment device 10 according to the present invention includes a housing 10a, a pair of rollers (cam followers) 11.11 that slide in contact with the tensioner 8 and rotate together with the tensioner 8, and the roller 11 is rotatably supported at one end. The base body 14 moves along a guide rail (not shown) inside the housing 10a and is fixed to the other end 12b of the support body 12, a pulse motor 15, and a control device 20. Consists of.

The drive shaft of the pulse motor 15 and the base I4 are connected to a ball screw 1.
6, and a ball screw 16 converts the rotational movement of the pulse motor 15 into translational movement of the base body 14.

As a result, as will be described in detail later, the base body 14 moves together with the support body 12 to press the roller 11 against the tensioner 8, and the belt tension is adjusted according to the amount of movement of the base body 14, that is, the amount of pushing of the roller 11. Ru.

The tensioner pushing load of the roller 11 is detected by a load cell 13 made of, for example, a strain gauge, and this load cell 13 is attached to the support body 12 near the other end 12a. Load cell 13 is electrically connected to the input side of control device 20 . The control device 20 includes an amplifier that amplifies the voltage waveform from the load cell 13, a central processing unit W (CPU) that calculates the pushing amount of the roller 11, controls the drive of the pulse motor 15, etc., and outputs a drive signal to the pulse motor 15. A sequencer that controls timing, output period, etc., a control program executed by the central processing unit, a storage device that stores initial values, etc. used in various calculations (none of these are shown), and drive to the pulse motor 15. The control device 20 is composed of a drive circuit 20a that outputs a signal, etc., and as will be described in detail later, the control device 20 controls the roller 11 detected by the load cell 13.
A drive signal is supplied to the pulse smoke 15 to rotate the pulse motor 15 forward or reverse according to the tensioner pushing load and the target pushing load.

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

The central processing unit of the control device 20 automatically adjusts the tension of the timing belt 2 by driving the pulse motor 15 according to the procedure shown in the flowchart of the belt tension adjustment program shown in FIG. More specifically, the engine 1 is attached to an adjustment frame (not shown), and the belt tension automatic adjustment device W10 is set at a predetermined position. At this time, loosen the tensioner bolt 8a of the tensioner 8, and
is in a state where it can move relative to the bracket 8b. Further, the tension spring 8c has been removed from the bracket 8b, and the tension spring 8 is pressed against the timing belt 8 by a roller 11 and is held between the timing belt 8 and the roller 11 of the automatic belt tension adjustment device 10.

When the belt tension automatic adjustment device 10 is operated in this state, the control device 20 first executes step Sl of the program shown in FIG. 2, and calculates and sets the initial pushing amount by the roller 11, which will be described later. This initial push amount is calculated by averaging the push amount at the time of completion of the adjustment, which is stored when belt adjustment was performed a predetermined number of times (for example, 10 times) before the current adjustment using the automatic belt tension adjustment device 10, and then calculates the initial push amount. It is a quantity. By calculating and setting the initial push amount in this way, even if timing belts 8 with different lofts are used, the optimum initial push amount can be learned and set for each loft, and as described later, the optimum initial push amount can be set. The correction of the pushing amount can be completed with a minimum number of times, which is effective in shortening the cycle time required to adjust the tension of the timing heald of the engine.

Next, the engine 1 is rotated at a predetermined rotational speed to start a break-in operation (step S3). Normally, at the beginning of the rotation of the engine 1, the belt tension decreases significantly due to the tooth surfaces of the timing belt 2 and the cam sprockets 3, 4, etc. fitting together. Therefore, a break-in operation for a predetermined period of time (for example, about 4 to 5 seconds) is required. In addition, the above-mentioned predetermined rotation speed can be set to an appropriate value, but if the rotation speed is too low, the adjustment time (cycle time) will be too long.
It is set to about 100rp1.

During this run-in operation, the pulse motor 15 is started to be driven (at time t1 in FIG. 3(C)), and the roller 11 is advanced by the initial push amount set in step S1 to apply initial tension to the timing belt 2 ( Step S5), the line diagram shown in FIG. 3(a) shows the time change of the belt pushing load value of the roller 11 detected by the load cell 13, and FIG. This is a change over time in the average value L cav of the pushing load values LC detected while the crankshaft of the engine I rotates twice.

Next, it is determined whether or not the break-in operation of the engine 1 has been completed (step S7). If the break-in operation has not been completed yet, the process waits until the break-in operation is completed.

By the time t2 when the break-in operation of the engine 1 is completed, the pushing load average value L CAV detected by the load cell 13
is statically determined as shown in FIG. 3(b).

Therefore, the control device 2
starts reading the pushing load value Lc of the roller z1 detected by the load cell 13 (at time t2 in FIG. 3(C)), and finishes reading when the crankshaft of the engine 1 has rotated twice (at time t3 in the same figure). The indentation load value read during this time.

Calculate the average value LcAv (step S9). Since the engine 1 is a V-type six-cylinder engine, the load signal value of the load cell 13 is calculated during two rotations of the crankshaft corresponding to the valve opening/closing timing of the valve mechanism. The peak value appears three times, but by averaging the load signal values Lc detected during this period, an indentation load that changes little over time can be determined. Then, calculate the calculated indentation load average value L CAV and the target load.

and determines whether the absolute value of this deviation is smaller than a predetermined value ΔL (time t4 in FIG. 3(C) and step 511 in FIG. 2).

If the determination result in step 311 is negative (No), the amount of pushing of the roll 11 is feedback-corrected according to the above-mentioned deviation (step 313).

Various methods can be considered for correcting the pushing amount, but the correction value for the pushing amount may be determined depending on the positive/negative of the deviation, the difference from the predetermined value ΔL, etc. A drive signal is output to the pulse smoke 15 in accordance with the correction value, and the belt tension of the timing belt 2 is adjusted by changing the belt pushing load of the roller 11. Then, when the correction of the pushing amount of the roller 11 is completed (Fig. 3 (C)
) At time L6 and time t9), the process returns to step S9, and steps S9, Sll, and 313 are repeatedly executed until the determination result at step Sll becomes affirmative.

If the determination result in step 311 becomes affirmative (Fig. 3 (
At point 10 in C), the control device 20 assumes that the tension adjustment of the timing belt 2 is completed, and stores the pushing amount of the roller 11 at the time of completion of the tension adjustment in the storage device (
Step 515). As described above, this stored value is used in step S1 to set the initial push amount when adjusting the timing belt tension to be executed later. Next, the operator stops the engine 1 (step 317), and in step S19 tightens the tensioner pusher 8a to fix the pivot position of the tensioner 8 relative to the bracket 8b, and then attaches the tensioner spring 8C to the bracket 8b to adjust the timing belt tension. Finish the adjustment.

For engines whose timing belt tension has been adjusted, after the adjustment, the belt tension is measured with the engine stationary using the free vibration method or the conventionally known Borrows force meter method, and belt tension fluctuations for each engine are measured. . The free vibration method involves lightly vibrating the belt on the tensile 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. In this method, the belt tension is determined by detecting the number using an FF analyzer and averaging the results. This method is preferable because it has a smaller measurement error than the belt tension determined by the conventionally known Borrows tension meter method. Comparing the variations in timing belt tension measured in this way from engine to engine when the engine is stationary, we find that Compared to the conventional belt adjustment performed by hand feeling, the belt adjustment performed by the apparatus of the present invention resulted in significantly smaller variations in belt tension from engine to engine.

In the above embodiment, the automatic belt tension adjustment device of the present invention was applied to adjust the belt tension of a timing belt. It can also be applied to belt tension adjustment of an endless belt wound between sprockets attached to the belt.

(Effects of the Invention) As detailed above, according to the belt tension automatic adjustment device 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 presses the tensioner to change the belt pressing force of the tensioner;
A roller driving means for advancing and retracting the roller relative to the tensioner, a load detection means for detecting the tensioner pushing load of the roller, and a roller tensioner pushing load detected by the load detecting means and a target pushing load stored in advance. and control means for calculating the pushing amount of the roller and outputting a drive signal to the roller drive means in accordance with the calculated value, and adjusting the tension of the endless belt while rotationally driving the internal combustion engine. Therefore, the belt tension is
It is possible to adjust to a predetermined value accurately and in a short time without involving the trouble of the worker.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall configuration diagram of an automatic heald tension adjustment device according to the present invention, and FIG. 2 is a flowchart showing a procedure for adjusting heald tension using the automatic belt tension adjustment device. FIG. 3 shows the pushing load on the roller 11 detected by the load cell 13 of the automatic belt tension adjustment device shown in FIG. It is a graph showing the relationship between the time change of the same indentation load average value LCAV, the time change of the same indentation load Lc, and the measurement timing of the same indentation load Lc. 1... Internal combustion engine, 2... Timing belt (endless bell), 3.4... Cam sprocket (driven wheel), 6... Crank sprocket (driving wheel), 8...
・Tensioner, 8a...Tensioner bolt, 8C...
・Tensioner spring, lO... Belt tension automatic adjustment device, 11... Roller, 13... Load cell (load detection means), 15... Pulse motor (roller drive means), 20... Control device ( control means). Applicant Mitsubishi Motors Corporation Agent Patent Attorney Kan Nagato 20a Figure 2 Procedures Amendment Statement) September 13, 1988

Claims (1)

[Claims] It rotates in response to the rotation of a tensioner that presses the endless belt that is wound between the driving wheels and driven wheels of an internal combustion engine to maintain a constant belt tension, and also presses the tensioner to increase the belt pressing force of the tensioner. a roller that changes the tensioner, a roller driving means that moves the roller forward and backward with respect to the tensioner, a load detection means that detects the tensioner pushing load of the roller, and a roller tensioner pushing load and the tensioner pushing load detected by the load detecting means. and a control means for calculating the pushing amount of the roller according to a target pushing load stored in advance, and outputting a drive signal to the roller driving means according to the calculated value, while rotating the internal combustion engine. An automatic belt tension adjustment device that adjusts the tension of the endless belt.