JP4360554B2 - transmission - Google Patents

Description

  The present invention relates to a transmission for an automobile provided with a pump with a chain drive.

  In recent years, in addition to a normal AT that uses a planetary gear, a CVT that performs a continuously variable transmission using a belt has become widespread as an automobile transmission. Such a transmission is a planetary gear type transmission mechanism including a clutch or a brake (usually a multi-plate friction engagement element) that is driven (engaged or released) by hydraulic pressure (hydraulic pressure) at the time of shifting, or It has a belt-type transmission mechanism including pulleys (primary pulley and secondary pulley) that are driven by hydraulic pressure during shifting to change the belt groove width.

  By the way, in recent years, as seen in Patent Document 1 and Patent Document 2, an oil pump for generating hydraulic pressure is disposed away from an input shaft (a shaft connected to an output shaft of an engine) of the transmission mechanism, and the input shaft side And a sprocket of the oil pump are connected by a chain, and a transmission having a configuration in which the oil pump is driven via the chain by the input shaft has been proposed. This is a configuration that realizes downsizing in the axial direction and the like by disposing an oil pump that has been conventionally disposed on the input shaft at a position separated from the input shaft.

JP 2003-156127 A JP 2004-92865 A Japanese Patent Laid-Open No. 2000-282887

However, in the above-described transmission (equipped with an oil pump with a chain drive), a model in which sound vibration (so-called chain ze noise) is generated at the portion of the chain that drives the oil pump, particularly in the low engine speed range. There was a problem.
Patent Document 3 discloses a technique for reducing the vibration of the chain that drives the camshaft of the engine so as not to cause a step in the mounting height of the chain tensioner and the tension adjuster. As a measure for improving sound vibration, the effect is unknown, and there is a problem that the structure is complicated and the cost is increased.

  Accordingly, an object of the present invention is to provide a transmission including an oil pump with a chain drive, which can suppress the above-described sound vibration by control.

The transmission of the present application includes a pump that is driven via a chain by an input shaft to which the rotation of the engine is transmitted, and is hydraulically controlled based on a line pressure obtained by adjusting the output of the pump as necessary. In a transmission that transmits the rotation of the input shaft by a speed change mechanism at a required speed ratio to the output shaft,
The sound that suppresses the sound vibration by forcibly changing the line pressure with respect to the sound vibration of the chain that occurs in a specific range where the engine speed and the line pressure value are outside the specific range. Control means for performing vibration countermeasure control is provided.

Here, "forcibly change" means changing from the normal line pressure required to shift control.
In addition, “the engine speed and the line pressure value are forcibly changed with respect to the vibration of the chain generated in a specific range to be out of the specific range ”, for example, There may be an aspect described in Item 2 or Claim 3.
That is, as the sound vibration countermeasure control, as described in claim 2, when the value of the line pressure accompanying the engine speed change is immediately before the sound vibration area in which the sound vibration is generated, There may be a mode in which the line pressure is forcibly increased to a first predetermined value outside the sound vibration region.
In addition, as the sound vibration countermeasure control, as described in claim 3, when the value of the line pressure accompanying the engine speed change is immediately before the sound vibration area in which the sound vibration is generated, There may be a mode in which the line pressure is forcibly reduced to a second predetermined value outside the sound vibration region.
In the case where a belt-type transmission mechanism is provided, in the aspect described in claim 3, as described in claim 4, the second predetermined value is at least within a range in which belt slip does not occur. Furthermore, it is preferable that the value is within a range in which a necessary shift speed and shift followability can be sufficiently secured.

  And, as a preferred aspect of the present invention, as described in claim 5, after the control means executes the sound vibration countermeasure control, at least the line pressure is compulsorily until it leaves the sound vibration area. The changed state is maintained, and the line pressure is returned to a normal value at the time when the sound vibration region due to the engine speed and the line pressure is removed.

  Alternatively, as described in claim 6, after the control means forcibly changes the line pressure, the line pressure may be returned to a normal value after a set holding time has elapsed. In this case, as described in claim 7, when the control means executes the sound vibration countermeasure control, or after executing the sound vibration countermeasure control, the time until it leaves the sound vibration area is determined based on the change gradient of the engine speed. A time obtained by estimating and adding a margin value to the time as necessary may be set as the holding time. Further, as described in claim 8, when the engine speed is within the sound vibration region when the control means executes or performs the sound vibration countermeasure control, and there is no change in the engine speed. Is configured to hold the state in which the line pressure is forcibly changed without setting the holding time, and to set the holding time when a change occurs in the engine speed. It is good also as a structure which returns a pressure to a normal value.

  According to a ninth aspect of the present invention, when the control means returns the line pressure that has been forcibly changed to a normal value, the line pressure is stepwise or predetermined outside the sound vibration region. It is good also as a structure which changes gradually with a change gradient.

The transmission of the present application forcibly changes the line pressure with respect to the vibration of the chain generated in a specific range of the engine speed and the line pressure , thereby causing the above-mentioned sound to be out of the specific range. Control means for performing sound vibration countermeasure control for suppressing vibration is provided. For this reason, generation | occurrence | production of the above-mentioned sound vibration can be avoided substantially. According to the inventors' research, it has been experimentally found that the above-mentioned sound vibration is generated only when the engine speed and the line pressure are within a specific range (sound vibration region). ing. That is, it is known that sound vibration occurs in a specific sound vibration region where a relationship between a specific engine speed and line pressure is established, and no sound vibration occurs when the line pressure is changed even if the engine speed is the same. For this reason, if the line pressure is forcibly changed based on the engine speed and the line pressure, the generation of sound vibration can be avoided and the generation can be stopped instantaneously.

  In addition, as described in claim 3, since the sound pressure countermeasure control for forcibly reducing the line pressure to the second predetermined value outside the sound vibration region is executed, the line pressure is reduced. This is advantageous. As described in claim 4, in the case of a transmission comprising a belt-type transmission mechanism, the second predetermined value (a value lower than the sound vibration region) is at least within a range where belt slip does not occur, and is desirable. Further, if the value is within a range that can sufficiently ensure the required shift speed and shift tracking performance, it is possible to avoid a decrease in shift performance (shift response, feeling, etc.) due to sound vibration countermeasure control.

  In addition, as described in claim 5, at least when the line pressure is forcibly changed until the sound vibration area is removed, and when the sound vibration area due to the engine speed and the line pressure is removed. The configuration for returning the line pressure to a normal value has the following effects. That is, when the sound vibration is generated, the line pressure is surely changed and the generation of the sound vibration is surely avoided, and when the sound vibration is finished, the line pressure is reliably increased. There is an advantage that the pressure can be returned to the normal value to return to the best state in terms of speed change performance and fuel consumption.

According to a sixth aspect of the present invention, when the line pressure is returned to a normal value after a set holding time has elapsed, it is determined whether or not a relatively complicated process (for example, whether or not the sound vibration area has been removed). There is an advantage that it is not necessary to carry out a process of determining.
Further, according to the seventh aspect of the present invention, when the holding time is set based on the engine speed change gradient, an appropriate holding time can be set according to the engine speed changing speed. The vibration countermeasure control (control for forcibly changing the line pressure from the normal value) can be executed and completed in the minimum necessary time.
Further, as described in claim 8, when there is no change in the engine speed, the engine speed is maintained when the line pressure is forcibly changed without setting the holding time. Although the actual number does not deviate from the sound vibration area when the line pressure is normal, it is possible to reliably avoid the occurrence of sound vibration due to the line pressure returning to the normal value due to the elapse of the holding time.

  In addition, as described in claim 9, when the line pressure is returned to a normal value, the line pressure is gradually changed outside the sound vibration region, so that a problem such as hunting due to a rapid change in the line pressure occurs. Occurrence of (deterioration of shift feeling, etc.) can be avoided. For example, if the line pressure is gradually returned in accordance with changes in the engine speed, the amount of sudden change in the line pressure to prevent sound vibration can be minimized at all times. Is advantageous.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating a schematic configuration of an automatic transmission (CVT) of this example. In the following description, the right side in FIG.
The automatic transmission of this example includes a torque converter 10, an oil pump 20, and a transmission mechanism 30 in a case (not shown), a control valve unit 40 at the lower portion of the case, and a control unit that is a control means. 50. This automatic transmission inputs the rotation of the engine 1 via the torque converter 10, changes the speed by a belt-type transmission mechanism 30 (continuously variable transmission mechanism) and a subsequent gear train, and outputs it to the axle side. It is. Note that a forward / reverse switching mechanism is usually provided at the front stage of the speed change mechanism 30, but this is not shown and description is omitted.

The torque converter 10 is a well-known one that appropriately decelerates the rotation of the engine 1 and transmits it to the input shaft 31 of the transmission mechanism 30 described later. In this case, the torque converter 10 includes a front cover 11 that is connected to the crankshaft 1 a of the engine 1 and rotates, a rear cover 12 that is connected to the rear portion of the front cover 11, and a pump impeller 13 that is formed inside the rear cover 12. A turbine runner 14 disposed opposite the pump impeller 13, a turbine shell 15 holding the turbine runner 14, a stator 16 disposed between the pump impeller 13 and the turbine runner 14, and a stator 16 A one-way clutch 17 to be supported and a lock-up piston 18 disposed between the front cover 11 and the turbine shell 15, and oil is supplied into the chamber formed by the front cover 11 and the rear cover 12. It is.
Here, the crankshaft 1a (which may be a shaft integrally connected to the crankshaft) corresponds to an input shaft to the transmission.

The engine side end of the input shaft 31 of the speed change mechanism 30 is inserted through the center axis of the torque converter 10, and the turbine shell 15 and the lockup piston 18 are connected to the engine side end of the input shaft 31 at the inner periphery thereof. It is connected to the part.
The rear cover 12 is integrally formed with a cylindrical pump drive shaft 12a extending to the opposite engine side, and a pump drive sprocket 19 is fixed to the outer periphery of the pump drive shaft 12a.

  The oil pump 20 is, for example, a gear pump. When the input shaft 21 rotates, oil in an oil pan (not shown) attached to the lower surface side of the case 10 is sucked to generate a predetermined hydraulic pressure. A sprocket 22 is fixed to the input shaft 21 of the oil pump 20 at a position corresponding to the sprocket 19 described above, and a chain 23 is stretched between the sprockets. Thereby, the rotation of the crankshaft 1a (input shaft to the transmission) that is the output shaft of the engine 1 is transmitted to the input shaft 21 of the oil pump 20 via the chain 23, and the oil pump 20 is rotated by the rotation of the engine 1. Driven.

The pressure oil generated by the oil pump 20 is supplied to the speed change mechanism 30 (a primary oil chamber 32c and a secondary oil chamber 34c, which will be described later) via the control valve unit 40, and also to the torque converter 10 and bearings at various places. Is done.
In the control valve unit 40, there is provided an electromagnetic valve (not shown) that adjusts the hydraulic pressure generated by the oil pump 20 as necessary to generate a line pressure. By controlling this electromagnetic valve, The control unit 50 can change the line pressure steplessly.

The speed change mechanism 30 is connected to an input shaft 31 and has a primary pulley 32 whose belt groove width is changed by the action of a primary pressure using the line pressure as a base pressure, and is connected to an output shaft 33 and uses the line pressure as a base pressure. A secondary pulley 34 whose belt groove width is changed by the action of the secondary pressure, and a V-belt 35 spanned between the pulleys, and the contact radius between each pulley and the belt depends on the primary pressure and the secondary pressure. By changing, it is of the belt type that changes the gear ratio.
Here, the primary pulley 32 includes a fixed conical plate 32a fixed to the outer periphery of the input shaft 31, and a movable conical plate 32b attached to the fixed conical plate 32a so as to be movable in the axial direction. V-shaped belt grooves (grooves with which the V belt 35 contacts) are formed. A primary oil chamber 32c is formed on the back surface of the movable conical plate 32b, and the movable conical plate 32b moves in the axial direction in accordance with the primary pressure applied to the primary oil chamber so that the belt groove width changes. ing.

The secondary pulley 34 includes a fixed conical plate 34a fixed to the outer periphery of the output shaft 33 and a movable conical plate 34b attached to the fixed conical plate 34a so as to be movable in the axial direction. A V-shaped belt groove is formed. And the secondary oil chamber 34c is formed in the back surface of the movable cone plate 34b, and the movable cone plate 34b moves in the axial direction in accordance with the secondary pressure applied to the secondary oil chamber 34c, and the belt groove width changes. It has become.
Note that the secondary pressure is a value equal to the normal line pressure.
Further, the output shaft 33 of the speed change mechanism 30 is connected to a differential of a driving wheel of an automobile via a gear train including an idler gear (not shown) to drive the driving wheel.

  Next, the control valve unit 40 includes a plurality of solenoid valves controlled by the control unit 50, manual valves that operate in response to the operation of the select lever, and the like in a body in which a control oil passage is formed. A valve is attached to form a hydraulic control circuit. Normally, it is attached to the lower surface of the case covered with an oil pan, and is generated by the hydraulic pump 20 based on the operation of the select lever and control of the control unit. The pressure oil to be supplied is appropriately supplied to a predetermined oil chamber or the like of the torque converter 10 or the speed change mechanism 30 through a predetermined oil passage formed in the case or the like while adjusting the pressure as necessary. Thereby, each part of the transmission mechanism 30 is lubricated and cooled, and the lock-up piston 18 of the torque converter 10 and the above-described movable conical plates 32b and 34b of the transmission mechanism 30 are appropriately operated. .

  The control unit 50 is composed of, for example, a microcomputer and is connected to the engine control unit 2 that controls the engine 1 to exchange information and to control the entire transmission via the control valve unit 40. The control unit 50 functions as control means for performing sound vibration countermeasure control for suppressing sound vibration of the chain 23 by forcibly changing the line pressure based on the engine speed and the line pressure.

  According to the inventors' research, at least in the configuration shown in FIG. 1, the values of the engine speed and the line pressure (that is, the secondary pressure) are in a specific range (sound vibration region; for example, FIG. ) And (b)), it has been experimentally found that sound vibration (so-called chain ze sound) occurs in the chain 35 portion.

Next, FIG. 2 is a flowchart showing a line pressure control process (including sound vibration countermeasure control) by the control unit 50.
When activated, the control unit 50 first performs a normal travel mode determination process in step S1. This travel mode determination process is a process for determining a travel mode for calculating a target line pressure (that is, secondary pressure Psec). It should be noted that the target line pressure is normally set so that the required speed change performance can be satisfied for each travel mode (at least the slip of the V belt 35 does not occur, and the required speed change and speed change followability are sufficiently ensured. For example, the value is set to the minimum necessary value according to the gear ratio (set as a relationship between the gear ratio and the line pressure).
Next, in step S2, it is determined whether the sound vibration countermeasure control trigger is turned on. If it is turned on, the process proceeds to step S3, and if not, the process proceeds to step S5. Note that “the sound vibration countermeasure control trigger is turned on” means that the condition for transition to the sound vibration countermeasure control is satisfied, and that the engine speed and line pressure values are immediately before the sound vibration area. is there. Specifically, for example, the value of the engine speed becomes a value within a predetermined range set in advance corresponding to the line pressure. Here, the predetermined range is a range obtained by expanding a sound vibration region (for example, a range determined by an experiment) in which the above-described sound vibration is generated by a predetermined margin value. In this case, the value of the engine speed at the time when the sound vibration countermeasure control trigger is turned on differs depending on whether the engine speed is increasing or decreasing, as shown in FIG.

Next, in step S3, the target line pressure is forcibly set (that is, irrespective of the relationship between the gear ratio and the line pressure) to the vibration avoidance hydraulic pressure (corresponding to the first predetermined value of the present invention). Here, the sound vibration avoidance hydraulic pressure is a value larger by a predetermined margin than the maximum value of the predetermined range (the range corresponding to the sound vibration region) of the line pressure specified with respect to the engine speed at that time. is there. This sound vibration avoidance hydraulic pressure may be set in advance for each engine speed, for example, through an experiment or the like.
Next, after step S3, the process proceeds to step S4, where it is determined whether or not the sound vibration countermeasure control signal is turned off. If it is turned off, the process proceeds to step S5, and if not turned off, the process returns to step S3. Note that “the sound vibration countermeasure control signal is turned off” means that the cancellation condition of the sound vibration countermeasure control is satisfied. For example, the value of the engine speed is set to the predetermined range (corresponding to the line pressure). This is a value deviating from a predetermined range set in advance.

  In step S5, the control unit 50 sets the target line pressure (that is, the secondary pressure Psec) to a normal value (according to the speed ratio for each travel mode so that the required speed change performance can be satisfied). To the normal control value.

According to the transmission of the present example described above, when the engine speed reaches or approaches a specific sound vibration area formed by the engine speed and the line pressure, the sound vibration countermeasure control signal is turned on and step S3 is executed. The target line pressure is forcibly set to the sound vibration avoiding hydraulic pressure. For this reason, the values of the engine speed and the line pressure at which sound vibrations occur are values outside the sound vibration region, and generation of sound vibrations can be avoided.
In this example, after the sound vibration countermeasure control is executed, the line pressure is forcibly changed at least until the engine speed and the line pressure are out of the sound vibration region, and the engine speed and the line pressure are maintained. Is configured to return the line pressure to a normal value on the basis of the fact that the sound pressure region is out of range. For this reason, when the engine speed and the line pressure are within the sound vibration region where the sound vibration is generated, the state in which the line pressure is changed outside the sound vibration region is reliably maintained and the generation of the sound vibration is reliably avoided. There is an advantage that when the sound vibration can be avoided from the sound vibration region, the line pressure can be surely returned to the normal value to return to the best state in terms of speed change performance and fuel consumption.

  FIG. 3A is a diagram showing an example of a numerical change at the time of vehicle deceleration when the horizontal axis is the engine speed and the vertical axis is the secondary pressure (line pressure). In this case, before the speed change, the engine speed decreases from the right side to the left side of the drawing while the secondary pressure (line pressure) is maintained at a value corresponding to the speed ratio before the speed change. Then, the speed change operation starts near the position indicated by the symbol a, and the speed change ratio changes until the speed change operation ends at the position indicated by the reference number b. Correspondingly, the secondary pressure changes to the speed ratio after the speed change. It changes to the corresponding normal value. Next, after the shift is completed, the engine speed decreases from the right side to the left side of the figure while the secondary pressure is maintained at the normal value corresponding to the speed ratio after the shift, but the secondary pressure remains at the normal value. During this time, the sound vibration area is slowly traversed, and sound vibration is generated at this time. However, in the present example, as shown by the half line in the figure, the secondary pressure is forcibly released just before and near the sound vibration area, and the sound pressure avoiding oil pressure (out of the sound vibration area) is controlled by the above-described sound vibration countermeasure control. Rise to high oil pressure). For this reason, the generation of sound vibrations is instantaneous and does not cause a problem.

  Next, FIG. 4 shows a specific example of a change in numerical values when the vehicle is decelerated (for example, when the vehicle decelerates from a running state to a stop by braking on) when the horizontal axis is time and the engine speed and secondary pressure are vertical axes. It is a figure which shows an example (experiment result). In this case, the speed change operation is started in the vicinity indicated by the symbol a, and the speed change ratio is changed until the speed change operation is ended in the vicinity indicated by the symbol b, and the secondary pressure is a normal value corresponding to the speed change ratio after the speed change. It changes to become. Therefore, the engine speed decreases, and the sound vibration region is slowly traversed near the end of the shift, and sound vibration is generated. However, if this example is applied, the above-described sound vibration countermeasure control causes the secondary pressure to be forcibly reduced in the range crossing the sound vibration region and in the vicinity thereof as shown by the half line in the figure. Therefore, the generation of sound vibration is not a problem.

  Next, FIG. 5 shows a specific example (experimental result) of a numerical change during vehicle acceleration (for example, when the vehicle starts from a stopped state) when the horizontal axis is time and the engine speed and secondary pressure are vertical axes. FIG. In this case, the speed change operation is started in the vicinity indicated by the symbol a, and the speed change ratio is changed until the speed change operation is ended in the vicinity indicated by the symbol b, and the secondary pressure is a normal value corresponding to the speed change ratio after the speed change. It changes to become. Therefore, sound vibration is generated by slowly traversing the sound vibration area during shifting. However, if this example is applied, the above-described sound vibration countermeasure control causes the secondary pressure to be forcibly reduced in the range crossing the sound vibration region and in the vicinity thereof as shown by the half line in the figure. Therefore, the generation of sound vibration is not a problem.

The present invention is not limited to the above-described embodiments, and various modifications and applications are possible.
For example, the sound vibration countermeasure control in the above embodiment is forcibly increasing the line pressure to a first predetermined value outside the sound vibration area (a value higher than the sound vibration area). May forcibly reduce the line pressure to a second predetermined value outside the sound vibration area (a value lower than the sound vibration area) (see FIG. 3B). In this case, the line pressure is reduced, which is advantageous in terms of fuel consumption. In the case of a transmission including a belt-type transmission mechanism, the second predetermined value (a value lower than the sound vibration region) is at least within a range in which belt slip does not occur. It is preferable that the value is within a range that can secure sufficient properties. If it does so, it can avoid that transmission performance falls by sound vibration countermeasure control.

Further, after the line pressure is forcibly changed in the sound vibration countermeasure control, when the set holding time has elapsed, the line pressure may be returned to a normal value, assuming that the cancellation condition of the sound vibration countermeasure control is satisfied. . For example, as shown in FIG. 3 (c), when the control means (for example, the control unit 50 in the above embodiment) executes the sound vibration countermeasure control or after executing it, the engine speed is changed based on the change gradient of the engine speed. It is obtained by estimating the time (for example, ΔT1 or ΔT2 shown in FIG. 3C) until the number is out of the sound vibration region when the number is a normal line pressure, and adding a margin value to the estimated time as necessary. The time may be set as the holding time. The margin value may or may not be added.
As described above, if the sound vibration countermeasure control is canceled based on the holding time, there is an advantage that it is not necessary to perform relatively complicated processing (for example, processing for sequentially determining whether or not the sound vibration area has been removed). is there. Moreover, if the holding time is set based on the gradient of the engine speed, an appropriate holding time can be set according to the changing speed of the engine speed as shown in FIG. (Control for forcibly changing the line pressure from the normal value) can be executed for the minimum necessary time and terminated.

  When the holding time is set as described above, the engine speed and the line pressure are within the sound vibration area when the sound vibration countermeasure control is executed or after execution, and the engine speed does not change. Holds the state in which the line pressure is forcibly changed without setting the holding time, sets the holding time when the engine speed changes, and after the holding time has elapsed, the line pressure is set. A mode in which is returned to a normal value is preferable. In this way, the engine speed and line pressure are not actually deviated from the sound vibration area, but it is ensured that the line pressure returns to the normal value due to the elapse of the holding time and the sound vibration is generated. Can be avoided.

  Further, when the line pressure forcibly changed by the sound vibration countermeasure control is returned to the normal value, the line pressure may be changed stepwise or gradually with a predetermined change gradient. By doing so, it is possible to avoid the occurrence of problems such as hunting due to a rapid change in line pressure. In addition, for example, if the line pressure is gradually returned in accordance with the change in the engine speed, the amount of change in the line pressure for preventing sound vibration can always be minimized, which is advantageous in improving fuel consumption. It becomes.

  The present invention may be applied to a belt type continuously variable transmission (CVT) without a torque converter, and may be applied to a stepped transmission (AT) using a planetary gear mechanism.

  Further, as a developmental configuration from the present invention, in the sound vibration countermeasure control, instead of forcibly changing the line pressure, the characteristics of the shift line (the relationship between the vehicle speed and the engine speed as the control target of the shift control) are changed. There may be a configuration in which the condition for generating the sound vibration is avoided by changing.

It is a figure explaining schematic structure of an automatic transmission. It is a flowchart which shows the process (including sound vibration countermeasure control) of line pressure control. (A) is a figure which shows an example of a sound vibration area | region and a numerical change, (b) is a figure explaining a sound vibration area | region and a sound vibration countermeasure control trigger, (c) is based on the change gradient of an engine speed. It is a figure explaining estimated holding time. It is a figure which shows the specific example of a time-sequential numerical change at the time of vehicle deceleration. It is a figure which shows the specific example of the time-sequential numerical change at the time of vehicle acceleration.

Explanation of symbols

1 Engine 1a Crankshaft (transmission input shaft)
23 Chain 20 Pump 30 Transmission mechanism 32 Primary pulley 33 Output shaft 34 Secondary pulley 35 V belt 50 Control unit (control means)

Claims (9)

A pump that is driven via a chain by an input shaft to which the rotation of the engine is transmitted, and the input shaft is controlled by a transmission mechanism that is hydraulically controlled based on a line pressure obtained by adjusting the output of the pump as necessary. In a transmission that changes the rotation of the motor at a required gear ratio and transmits it to the output shaft
The sound that suppresses the sound vibration by forcibly changing the line pressure with respect to the sound vibration of the chain that occurs in a specific range where the engine speed and the line pressure value are outside the specific range. A transmission comprising control means for performing vibration countermeasure control. In the sound vibration countermeasure control, when the value of the line pressure accompanying the change in the engine speed is immediately before the sound vibration area that is the range in which the sound vibration is generated, the line pressure is set to the first outside the sound vibration area. The transmission according to claim 1, wherein the transmission is forcibly increased to a predetermined value. In the sound vibration countermeasure control, when the value of the line pressure accompanying the engine speed change is immediately before a sound vibration area that is a range in which the sound vibration is generated, the line pressure is set to a second value outside the sound vibration area. The transmission according to claim 1, wherein the transmission is forcibly reduced to a predetermined value. The transmission mechanism includes a primary pulley that is connected to the input shaft side and changes the belt groove width by the action of a primary pressure based on the line pressure, and a secondary pressure that is connected to the output shaft side and is the line pressure. A belt pulley having a belt groove width that changes due to the action, and a belt stretched between the pulleys, and the contact radius of each pulley and the belt changes according to the primary pressure and the secondary pressure, thereby changing the transmission ratio. It is of the belt type that changes
The first predetermined value is immediately before the sound vibration area, and is equal to or greater than an upper limit value of the sound vibration area when the engine speed is a constant value.
The transmission according to claim 2 or 3, wherein the second predetermined value is a value within a range in which the belt does not slip. The control means maintains the state in which the line pressure is forcibly changed at least until the sound vibration area is removed after the sound vibration countermeasure control is executed, and the sound vibration area based on the engine speed and the line pressure is maintained. The transmission according to any one of claims 1 to 4, wherein the line pressure is returned to a normal value at the time of deviating. 5. The control unit according to claim 1, wherein the control unit changes the line pressure to a normal value after a lapse of a set holding time after forcibly changing the line pressure. transmission. The control means estimates a time until the sound vibration area is deviated based on a change gradient of the engine speed when or after the sound vibration countermeasure control is executed, and has a margin as needed for the time. The transmission according to claim 6, wherein a time obtained by adding the values is set as the holding time. When the engine speed is within the sound vibration area and there is no change in the engine speed when or after executing the sound vibration countermeasure control, the control means does not set the holding time and does not set the holding time. The state in which the line pressure is forcibly changed is maintained, the holding time is set when a change occurs in the engine speed, and the line pressure is returned to a normal value after the holding time has elapsed. The transmission according to any one of claims 6 to 7. The control means, when returning the forcibly changed line pressure to a normal value, gradually changes the line pressure stepwise or with a predetermined change gradient outside the sound vibration region. The transmission according to any one of claims 1 to 8.

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