JP2011169375A - Auxiliary driving gear and hydraulic control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic control device capable of satisfying a plurality of kinds of hydraulic characteristics while reducing the weight and the cost of the device with a simple constitution. <P>SOLUTION: The hydraulic control device 60 has an oil pump 50-3 to be driven by an auxiliary driving gear 1 having an electric motor 10 capable of changing the forward-reversal rotational direction, and a speed change mechanism 20 having a planetary gear mechanism PT and two one-way clutches 25, 27. When the electric motor 10 is rotated in the forward direction, the driving force having the characteristic of low-torque and high-rotation is output in the first transmission path in which the first one-way clutch 25 is operated, and the oil pump 50-3 is driven with the low pressure and high capacity. On the other hand, when the electric motor 10 is rotated in the reverse direction, the driving force having the characteristic of low-torque and high-rotation is output in the second transmission path in which the second one-way clutch 27 is operated, and the oil pump 50-3 is driven with the high pressure and low capacity. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an accessory driving device for driving an accessory such as a hydraulic pump provided in a transmission, and a hydraulic control device including a hydraulic pump driven by the accessory driving device.

  The automatic transmission is provided with a hydraulic control device that supplies hydraulic pressure for operation of a hydraulic servo mechanism for clutches and brakes for shift control, lubrication and cooling of each operation unit, and the like. In such a hydraulic control apparatus, conventionally, an oil pump that is mechanically driven by rotation on the pump side of a torque converter that rotates at an engine speed (engine speed) has been mainly used as a hydraulic pressure generation source. . However, in a hydraulic control device for a transmission used in a vehicle equipped with an electric motor as a drive source, an oil pump driven by the engine is usually stopped when the engine is stopped at the time of idling stop or EV running in a hybrid vehicle or the like. . Therefore, it is necessary to secure the oil pressure for shift control and the oil pressure for lubrication by another means. Therefore, in an electric vehicle or a hybrid vehicle, a hydraulic control system including an oil pump driven by an electric motor is employed so that the supply of hydraulic pressure can be controlled regardless of the traveling state of the vehicle. As such a hydraulic control system, there are hydraulic control apparatuses shown in Patent Documents 1 and 2.

  The hydraulic control device described in Patent Document 1 is configured to use an oil pump as a hydraulic energy source to lubricate each part of the mechanism by supplying oil and to operate a hydraulic servo for shift control. This hydraulic control device includes a lubrication circuit to which hydraulic oil is constantly supplied, an accumulator for accumulating the supplied oil and supplying the hydraulic servo, and selectively connecting the oil pump to the lubrication circuit and the accumulator Has a valve. According to the hydraulic control apparatus described in Patent Document 1, the capacity of the oil pump can be reduced by the operation of a hydraulic servo by accumulator pressure accumulation, and in accordance with the supply of hydraulic oil to the lubricating circuit when pressure accumulation to the accumulator is completed. Hydraulic energy loss is reduced by using low-load operation.

  The hydraulic pressure supply device described in Patent Document 2 includes a high-pressure pump that accumulates an accumulator that operates a hydraulic actuator that starts an engine, and a low-pressure pump that supplies low-pressure hydraulic oil to an automatic transmission. A high-pressure pump and a low-pressure pump are connected to the rotating shaft of the electric motor capable of forward and reverse rotation via first and second one-way clutches having different engagement directions. Accordingly, the high pressure pump is operated by rotation in one direction of the electric motor, and the low pressure pump is operated by rotation in the other direction.

JP 2004-84928 A JP 2003-156132 A

  The hydraulic control device described in Patent Document 1 has a configuration including one pump and one motor, but obtains a plurality of different pump characteristics of high pressure / small capacity and low pressure / large capacity by controlling the electric motor. I am doing so. However, since the electric motor is used in the low rotation high torque region and the high rotation low torque region, it is necessary to increase the size and output (high voltage) of the electric motor. For this reason, there is a risk of increasing the cost and weight of the hydraulic control device. Moreover, since the use area | region of the above electric motors is an area | region where motor efficiency is generally not so high, the loss of the drive energy of an electric motor will increase.

  In addition, in the hydraulic control device described in Patent Document 1, as a structure to compensate for insufficient lubrication in the lubrication circuit, the accumulator pressure accumulation value is set higher than that during normal running during start standby, The drain is connected to the lubrication circuit. However, with such a structure, a large capacity pump characteristic is required at high pressure, and an electric motor with a large output is required. In addition, since it must be used at a higher pressure than normal, further higher output is required. As a result, the electric motor is increased in size and voltage, and the hydraulic system on the high-pressure side is required to cope with a higher pressure, which may lead to an increase in cost.

  Moreover, in the hydraulic pressure supply apparatus described in Patent Document 2, two types of required hydraulic pressure characteristics are established by using two pumps properly. Therefore, efficient operation of the electric motor is possible. However, since two pumps are provided, there is a problem that it is difficult to reduce the size of the apparatus and simplify the configuration, which leads to an increase in cost.

  As described above, in the conventional hydraulic control device, by switching the pump characteristics for high pressure and low pressure, the high pressure is used for transmission control and the low pressure is used for lubrication, thereby reducing energy consumption. At the same time, an idea to prevent the system from becoming large has been proposed. However, since the apparatus of the prior art requires two pumps, or even a single pump requires a variable displacement mechanism, the apparatus can be downsized, the configuration can be simplified, and the cost can be reduced. There was a problem that it could not be done easily.

  The present invention has been made in view of the above points, and is an auxiliary machine drive capable of outputting a plurality of driving forces having different characteristics while reducing the weight and cost of the apparatus with a simpler configuration than conventional ones. It is an object of the present invention to provide a hydraulic control apparatus capable of outputting a plurality of different hydraulic characteristics by a hydraulic pump driven by the apparatus and the accessory driving apparatus.

  In order to solve the above-described problems, an accessory driving apparatus according to the present invention includes an electric motor (10) and a transmission mechanism (20) having a planetary gear mechanism (PT) capable of changing the rotation of the electric motor (10). And an auxiliary machine drive device (1, 1-2) for driving the auxiliary machine (50) with an output from the transmission mechanism (20), wherein the electric motor (10) can switch between forward and reverse rotation directions. Yes, the planetary gear mechanism (PT) outputs the driving force to the first element (S or R) connected to the input shaft (21) to which the driving force of the electric motor (10) is input and the auxiliary device (50). A third element (R or S) connected to the output shaft (22), a second element (C) meshing with the first element (S) and the third element (R), and a first element (S) The first one-way clutch (25) provided between the third element (R), the second element (C) and the fixed-side member (23 A second one-way clutch (27) provided between the first and the second one-way clutches (25). The first one-way clutch (25) is operated in the planetary gear mechanism (PT) by rotating the electric motor (10) in the forward direction. Power is transmitted through one transmission path, and the driving force having the first characteristic is output from the output shaft (22), while the electric motor (10) rotates in the reverse direction, whereby the planetary gear mechanism (PT). , Power is transmitted through a second transmission path in which the second one-way clutch (27) is operated, and a driving force having a second characteristic different from the first characteristic is output from the output shaft (22). And

  According to the accessory drive device of the present invention, although it has a simple configuration including a single electric motor that can switch forward and reverse in the rotation direction, and a speed change mechanism that combines a planetary gear mechanism and two one-way clutches. Thus, it becomes possible to output a driving force having two different characteristics. Therefore, it is possible to drive and control two types of controlled objects having different characteristics of the required driving force even though the accessory driving device has a simple and inexpensive configuration. Further, in this auxiliary machine drive device, since the planetary gear mechanism is provided with a transmission mechanism in which two one-way clutches are combined, a driving force having two different types of characteristics can be obtained simply by switching the rotation direction of the electric motor. . Accordingly, the drive control of the auxiliary machine can be easily performed.

  As one embodiment of the accessory drive apparatus according to the present invention, the planetary gear mechanism (PT) is a single pinion type planetary gear mechanism (PT), and the first element is an input shaft (21 ), The third element is a ring gear (R) fixed to the output shaft (22), and the second element is a sun gear (S) and a ring gear (R). ) May be a carrier (C) having a pinion gear (P).

  According to this configuration, since the sun gear is fixed to the input shaft and the ring gear is fixed to the output shaft, the same output characteristics as in the case of the electric motor alone can be obtained as the first characteristics by the first transmission path. In addition, as the second characteristic by the second transmission path, it is possible to obtain a higher torque output characteristic than in the case of the electric motor alone. Therefore, this configuration is useful when driving an auxiliary machine that requires torque characteristics higher than the output characteristics of the electric motor alone.

  As another embodiment of the accessory drive device according to the present invention, the planetary gear mechanism (PT) is a single pinion planetary gear mechanism (PT), and the first element is an input shaft ( 21) is a ring gear (R) fixed to the output shaft (22), and the second element is a sun gear (S) and a ring gear (S). It may be a carrier (C) having a pinion gear (P) meshing with R).

  According to this configuration, since the ring gear is fixed to the input shaft and the sun gear is fixed to the output shaft, the same output characteristics as in the case of the electric motor alone can be obtained as the first characteristics by the first transmission path. In addition, as the second characteristic by the second transmission path, it is possible to obtain an output characteristic of higher rotation than that in the case of the electric motor alone. Therefore, this configuration is useful when driving an auxiliary machine that requires a higher rotation characteristic than the output characteristic of a single electric motor.

  The hydraulic control device according to the present invention includes a hydraulic pump (50-3) for supplying hydraulic oil to a transmission mounted on a vehicle, and a drive device (1, 1-2) for driving the hydraulic pump (50-3). ), And the drive device (1, 1-2) is the auxiliary drive device (1, 1-2) having the above-described configuration according to the present invention. In the hydraulic pump (50-3), the drive device (1 , 1-2) a first hydraulic characteristic (for example, a high discharge type hydraulic characteristic) is output corresponding to the driving force of the first characteristic output from 1-2), and corresponding to the driving force of the second characteristic. A second hydraulic characteristic different from the first hydraulic characteristic (for example, a high pressure type hydraulic characteristic) is output.

  According to the hydraulic control device of the present invention, a single electric motor and a single hydraulic pump can be obtained by using the auxiliary device driving device having the above configuration according to the present invention as a driving device for driving the hydraulic pump. While having a simple configuration, different hydraulic characteristics can be output. Therefore, as compared with a conventional hydraulic control apparatus including two pumps, the apparatus configuration can be simplified, reduced in size, reduced in weight, and reduced in cost.

  Further, in this hydraulic control device, two different hydraulic characteristics are output by the hydraulic pump corresponding to each of the two types of driving forces having different characteristics output from the accessory driving device according to the present invention. Two types of hydraulic characteristics can be used properly. Accordingly, it is possible to satisfy two different types of hydraulic characteristics required for the transmission such as transmission lubrication and transmission control.

  Further, in the hydraulic control device, the first hydraulic characteristic is output corresponding to the driving force of the first characteristic output from the driving device, and the driving force of the second characteristic output from the driving device. Since the second hydraulic characteristic different from the first hydraulic characteristic is output, it is possible to output two different hydraulic characteristics from the hydraulic pump only by switching the rotation direction of the electric motor. Become. Accordingly, the hydraulic control in the hydraulic control device can be easily performed.

  In the above hydraulic control apparatus, the discharge path for discharging the hydraulic oil from the hydraulic pump (50-3) includes the lubrication circuit (71) for lubricating the transmission and the discharged hydraulic oil in the accumulator (62). ) And a pressure accumulation circuit (73) for accumulating pressure and sending it to the control circuit (72) for shift control, and a discharge path switching means (65) for switching between the lubrication circuit (71) and the pressure accumulation circuit (73). ), And when the lubrication circuit (71) is selected by the discharge path switching means (65), the first hydraulic pressure is supplied from the hydraulic pump (50-3) by rotating the electric motor (10) forward. On the other hand, when the pressure accumulation circuit (73) is selected by the discharge path switching means (65) while the characteristic is output, the electric motor (10) is rotated in the reverse direction so that the second from the hydraulic pump (50-3). To output the characteristics of There.

  In the above hydraulic control device, the hydraulic pressure detection device (63) for detecting the hydraulic pressure of the hydraulic oil accumulated in the accumulator (62), and the hydraulic pressure control device (63) according to the hydraulic pressure detected by the hydraulic pressure detection device (63) 60, 60-4), and a control means (75) for controlling the supply hydraulic pressure. The control means (75) has a detection value of the hydraulic pressure detection means (63) lower than the first threshold value (P1). In this case, the discharge path switching means (65) switches from the lubrication circuit (71) to the pressure accumulation circuit (73), and at the same time immediately before switching from the lubrication circuit (71) to the pressure accumulation circuit (73) ( At t0), the operating state of the electric motor (10) is changed so that the discharge amount of the hydraulic pump (50-3) is increased more than before, and the detected value of the hydraulic pressure detecting means (63) is the second threshold value. Higher than (P2 or P2 ') And when, it may be performed to switch from the accumulator circuit (73) in the discharge path switching means (65) to the lubrication circuit (71).

  In view of its usage, the hydraulic control device according to the present invention may require supply (or increase) of hydraulic oil to the lubrication circuit during the pressure accumulation mode depending on the system (vehicle) to be applied. obtain. As a countermeasure for this, it is preferable to temporarily increase the amount of hydraulic oil supplied to the lubrication circuit before the transition from the lubrication mode to the pressure accumulation mode. According to this, the lubrication request | requirement with respect to the lubrication circuit after changing to a pressure accumulation mode can be satisfy | filled for a fixed period. Therefore, it is not necessary to take measures such as increasing the pressure of hydraulic oil supplied to the pressure accumulating circuit as in the prior art (Patent Document 1). Therefore, it is possible to prevent the occurrence of troubles such as seizure of the operating part in the transmission without increasing the size of the device and significantly increasing the energy consumption. In addition, it is possible to reduce energy consumption by minimizing the amount of lubrication while supplying hydraulic oil to the lubrication circuit (during the normal lubrication mode).

In the hydraulic control apparatus, the control means (75) has a function of determining the amount of lubrication necessary for the lubrication circuit (71), and the control means (75) has a function for determining the lubrication circuit (71). When it is determined that the amount of lubrication is larger than usual, the second threshold (P2) for switching from the pressure accumulation circuit (73) to the lubrication circuit (71) is set to a lower value. It may be changed to the threshold value (P2 ′). According to this structure, the supply time of the hydraulic oil to the pressure accumulation circuit can be shortened. Accordingly, even when the amount of hydraulic oil supplied to the lubrication circuit is large, it is possible to ensure the lubrication performance necessary for the transmission. Note that this configuration is preferably applied to a hydraulic control device for a transmission mounted on a vehicle in which a supply amount of hydraulic oil required for a lubrication circuit is relatively high due to a high load on an operating portion of the transmission. is there.
In addition, the code | symbol in said parenthesis shows the code | symbol of the corresponding component in embodiment mentioned later as an example of this invention.

  According to the accessory driving device of the present invention, the driving force having two different characteristics with respect to the accessory can be achieved with a simple configuration including a single electric motor while reducing the weight and cost of the device. Can be output. In addition, according to the hydraulic control device of the present invention, two different hydraulic characteristics can be output with a simple configuration in which a single oil pump is driven by the above-described auxiliary device driving device.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic (partially skeleton figure) which shows the structure of the auxiliary machinery drive device concerning 1st Embodiment of this invention. It is a figure for demonstrating operation | movement of the auxiliary machinery drive device of 1st Embodiment. It is a velocity diagram of the auxiliary machine drive device of 1st Embodiment. It is a graph which shows the output characteristic of the auxiliary machinery drive device of 1st Embodiment. It is the schematic which shows the structure of the auxiliary machinery drive device concerning 2nd Embodiment of this invention. It is a speed diagram of the auxiliary machine drive device of 2nd Embodiment. It is the schematic which shows the structure of the hydraulic control apparatus concerning 3rd Embodiment of this invention. It is a velocity diagram of the auxiliary machinery drive device with which the hydraulic control device of a 3rd embodiment is provided. It is a figure which shows the output characteristic of the auxiliary machinery drive apparatus with which the hydraulic control apparatus of 3rd Embodiment is provided. It is a graph which shows the change of the accumulator internal pressure in a hydraulic control apparatus. It is a flowchart which shows the procedure of the hydraulic control in a hydraulic control apparatus. It is a graph which shows the change of the accumulator internal pressure in a hydraulic control apparatus. It is a flowchart which shows the other procedure of the hydraulic control in a hydraulic control apparatus. It is the schematic which shows the structure of the hydraulic control apparatus concerning 4th Embodiment of this invention. It is a velocity diagram of an auxiliary machinery drive with which a hydraulic control device of a 4th embodiment is provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[First Embodiment]
FIG. 1 is a schematic diagram (partially skeleton diagram) showing a configuration of an auxiliary machine driving device according to a first embodiment of the present invention. As shown in FIG. 1, the accessory drive device 1 of the present embodiment includes an electric motor 10, an input shaft 21 to which driving force from the electric motor 10 is input, and a speed change mechanism 20 that changes the rotation of the input shaft 21. And an output shaft 22 for outputting the rotation shifted by the speed change mechanism 20 to the auxiliary machine 50 to be controlled. The electric motor 10 can switch between forward and reverse rotation directions. The transmission mechanism 20 includes a single pinion type planetary gear mechanism PT.

  The planetary gear mechanism PT of the present embodiment includes a sun gear (first element) S fixed to the input shaft 21, a ring gear (third element) R fixed to the output shaft 22, and both the sun gear S and the ring gear R. And a carrier (second element) C that supports the meshing pinion gear P.

  A first one-way clutch 25 is installed between the input shaft 21 to which the sun gear S is fixed and the ring gear R, and a casing (fixed member) 23 that houses the speed change mechanism 20, a carrier C, and the like. A second one-way clutch 27 is installed between the two. The first one-way clutch 25 is set to be actuated (restrained) by the rotation of the input shaft 21 in the forward direction, and the second one-way clutch 27 is actuated (restrained) by the rotation of the carrier C in the reverse direction. Is set.

  2A and 2B are diagrams for explaining the operation of the accessory drive device 1. FIG. 2A shows a case where power is transmitted through a first transmission path to be described later, and FIG. 2B shows a case where power is transmitted through a second transmission path. The case where it is transmitted is shown. FIG. 3 is a velocity diagram of the auxiliary machine driving device 1. In the auxiliary machine drive device 1 having the above configuration, as shown in FIG. 2A, when the electric motor 10 (input shaft 21) rotates in the forward direction, the first one-way clutch 25 of the planetary gear mechanism PT is operated. As a result, the rotation of the input shaft 21 is transmitted as it is to the ring gear R via the first one-way clutch 25 and is output from the ring gear R to the auxiliary device 50. Hereinafter, the transmission path on which the first one-way clutch 25 operates is referred to as a first transmission path. As the power is transmitted through the first transmission path, as shown in the speed diagram of FIG. 3, a driving force having a low torque high rotation characteristic (first characteristic) is output to the auxiliary machine 50. The

  On the other hand, as shown in FIG. 2B, when the electric motor 10 rotates in the reverse direction, the rotation of the input shaft 21 is transmitted from the sun gear S to the ring gear R through the pinion gear P, and output from the ring gear R to the auxiliary device 50. Is done. At this time, the operation of the first one-way clutch 25 is released, and the rotation of the carrier C is locked by operating the second one-way clutch 27 instead. Hereinafter, the transmission path on which the second one-way clutch 27 operates is referred to as a second transmission path. As the power is transmitted through the second transmission path, as shown in the speed diagram of FIG. 3, a driving force having a high torque low rotation characteristic (second characteristic) is output to the auxiliary machine 50. The

  That is, in the auxiliary machine drive device 1 of the present embodiment, when a driving force with a low torque and a high rotation is required as a driving force for the auxiliary machine 50, the electric motor 10 is rotated in the forward direction. Thus, when the first one-way clutch 25 is operated, the rotation of the electric motor 10 is directly output to the auxiliary machine 50 through the first transmission path. On the other hand, when a driving force of high torque and low rotation is required as a driving force for the auxiliary machine 50, the electric motor 10 is rotated in the reverse direction. As a result, the operation of the first one-way clutch 25 is released, and the carrier C is locked by operating the second one-way clutch 27 instead. Thus, the rotation that is decelerated (torque amplification) in the opposite direction to the rotation of the electric motor 10 by the second transmission path is output from the ring gear R to the auxiliary device 50. As described above, in the auxiliary machine driving device 1 of the present embodiment, it is possible to output two types of driving forces having different characteristics by switching between forward and reverse rotation directions of the electric motor 10.

  FIG. 4 is a graph showing the output characteristics of the auxiliary machine drive device 1. The horizontal axis in the graph of the figure is the rotational speed of the output shaft 22, and the vertical axis is the drive torque of the output shaft 22. When the electric motor 10 is rotated in the forward direction and power is transmitted through the first transmission path, a driving force having a low torque high rotation characteristic (first characteristic) is output as shown by a solid line in the graph. The On the other hand, when the electric motor 10 is rotated in the reverse direction and power is transmitted through the second transmission path, the driving force having the characteristics of high torque and low rotation (second characteristic) as shown by the one-dot chain line in the graph. Is output. Therefore, in the present embodiment, in the auxiliary machine driving device 1 having a single electric motor 10, the required characteristics that require high rotation / high speed as shown in the area of symbol A in FIG. Both required characteristics requiring high torque / high load as shown in the region can be satisfied. Note that the dotted line shown in the graph indicates that the electric motor drive device 1 according to the present embodiment does not use the speed change mechanism 20 and is intended to satisfy the above two types of required characteristics with only a single electric motor. It is a graph which shows the output characteristic required for a motor. In the auxiliary machine drive device 1 of the present embodiment, outputs having two different types of characteristics can be obtained depending on the speed change mechanism 20, so that the electric motor 10 can be operated with low output / high efficiency. Therefore, the output of the electric motor 10 can be reduced as compared with the output characteristics indicated by the dotted line. In other words, the two required characteristics of high torque (high load) and high rotation (high speed) can be satisfied without increasing the output (upsizing) of the electric motor 10.

In addition to an oil pump (hydraulic pump) 50-3 of a third embodiment to be described later, specific examples of the auxiliary machine 50 to be controlled by the auxiliary machine drive device 1 of the present embodiment include the following.
(1) Compressor for electric air conditioner The compressor for an electric air conditioner has a high cooling performance required only for a short time in the initial operation (immediately after the start of operation). When the temperature (room temperature) becomes constant to some extent, the required cooling performance decreases. Therefore, if the auxiliary machine driving device 1 according to the present embodiment outputs driving forces having different characteristics between the initial stage of driving and after the temperature becomes constant, the driving can be optimized.
(2) Electric fan (radiator, air conditioning), electric water pump These auxiliary machines can also optimize the operation if the auxiliary machine driving device 1 of the present embodiment outputs two different types of driving forces. it can.
(3) Shift actuator system for AMT (automatic manual transmission)

  As described above, according to the accessory drive device 1 of the present embodiment, the single electric motor 10 that can switch the forward and reverse rotation directions, the planetary gear mechanism PT, and the two one-way clutches 25 and 27 are provided. Although it is a simple structure provided with the combined transmission mechanism 20, it becomes possible to output driving force having two different characteristics. Accordingly, it is possible to drive and control two types of controlled objects having different characteristics of the required driving force, even though the accessory driving device 1 has a simple and inexpensive configuration. Further, in this auxiliary machine drive device 1, since the planetary gear mechanism PT is provided with the speed change mechanism 20 in which two one-way clutches 25 and 27 are combined, only two types of forward and reverse rotation directions of the electric motor 10 are switched. A driving force having different characteristics can be obtained. Therefore, the drive control of the auxiliary machine 50 can be easily performed.

  Further, the planetary gear mechanism PT provided in the accessory drive device 1 of the present embodiment has the sun gear S fixed to the input shaft 21 and the ring gear R fixed to the output shaft 22 as shown in FIG. As a result, as shown in the velocity diagram of FIG. 3, in addition to obtaining the same output characteristic as the case of the electric motor 10 alone as the first characteristic by the first transmission path, the second characteristic by the second transmission path is obtained. As a characteristic, it is possible to obtain a higher torque characteristic than in the case of the electric motor 10 alone. Therefore, this embodiment is a configuration useful when driving the auxiliary machine 50 that requires a torque characteristic higher than the characteristic of the electric motor 10 alone.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the description of the second embodiment and the corresponding drawings, the same or corresponding components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted below. In addition, matters other than those described below are the same as those in the first embodiment. This is the same in other embodiments.

  FIG. 5 is a schematic diagram (partially skeleton diagram) showing a configuration of an auxiliary machine drive device 1-2 according to the second embodiment of the present invention. FIG. 6 is a velocity diagram of the auxiliary machine driving device 1-2. The auxiliary machine drive device 1-2 of the present embodiment is different from the auxiliary machine drive device 1 of the first embodiment in the relationship of the constituent elements of the planetary gear mechanism PT. Other configurations are the same as those of the accessory drive device 1 of the first embodiment.

  In other words, the planetary gear mechanism PT included in the accessory driving device 1-2 of the present embodiment includes a ring gear R (first element) fixed to the input shaft 21 and a sun gear S (third element) fixed to the output shaft 22. ) And a carrier C (second element) that supports a pinion gear P that meshes with both the sun gear S and the ring gear R. The first one-way clutch 25 is installed between the output shaft 22 to which the sun gear S is fixed and the ring gear R, and the second one-way clutch 27 is installed between the carrier C and the casing 23. .

  In the auxiliary machine drive device 1-2 having the above-described configuration, the first one-way clutch 25 is operated by rotating the electric motor 10 in the forward direction, similarly to the auxiliary machine drive device 1 of the first embodiment. Thereby, the rotation of the input shaft 21 and the ring gear R is transmitted to the output shaft 22 via the first one-way clutch 25 as it is. In the first transmission path, as shown in the velocity diagram of FIG. 6, a driving force having a high torque low rotation characteristic (first characteristic) is output to the auxiliary machine 50. On the other hand, when the electric motor 10 rotates in the reverse direction, the rotation of the input shaft 21 is transmitted from the ring gear R to the sun gear S via the pinion gear P and output from the output shaft 22 to the auxiliary device 50. At this time, the carrier C is locked by operating the second one-way clutch 27. In the second transmission path, as shown in the velocity diagram of FIG. 6, a driving force having a low torque high rotation characteristic (second characteristic) is output to the auxiliary machine 50.

  That is, in the auxiliary machine drive device 1-2 of the present embodiment, when a driving force with a high torque and a low rotation is required as a driving force for the auxiliary machine 50, the electric motor 10 is rotated in the forward direction. As a result, the first transmission path is selected, and the rotation of the electric motor 10 is input to the auxiliary device 50 as it is. On the other hand, when a low torque and high rotation driving force is required as the driving force for the auxiliary machine 50, the electric motor 10 is rotated in the reverse direction. Thus, the second transmission path is selected, and the rotation speed increased in the direction opposite to the rotation of the electric motor 10 is output from the sun gear S to the auxiliary device 50.

  In the auxiliary drive device 1-2 of this embodiment, when a high-torque low-rotation type electric motor is used for the electric motor 10, the first transmission path (the so-called direct connection in which the input shaft 21 and the output shaft 22 are directly connected). There is a merit when used for driving the auxiliary machine 50 that is frequently used in (mode). In the driving force transmission by the first transmission path, the transmission efficiency in the planetary gear mechanism PT is 100% (no loss), whereas in the driving force transmission by the second transmission path (so-called speed increasing mode), As for the transmission efficiency in the planetary gear mechanism PT, a loss of two meshes (meshing loss) occurs through the sun gear S, the pinion gear P, and the ring gear R.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. FIG. 7 is a schematic diagram (partially skeleton diagram) showing a hydraulic control device 60 according to the third embodiment of the present invention. FIG. 8 is a velocity diagram of the accessory drive device 1 included in the hydraulic control device 60.

  The hydraulic control device 60 of the present embodiment is a hydraulic control device provided in a vehicle transmission (the entire configuration is not shown), and an oil pump 50-3 driven by the auxiliary device driving device 1 is used as a hydraulic energy source. As a hydraulic control device that lubricates a mechanism portion of the transmission by supplying hydraulic oil and operates a hydraulic servo mechanism for shift control. In the hydraulic control device 60, a lubricating circuit 71 and a pressure accumulating circuit 73 are set as discharge destinations of the hydraulic oil sucked from the oil tank 61 to the oil pump 50-3. The lubrication circuit 71 is a circuit for supplying lubricating oil (hydraulic oil) to various operation mechanisms provided in the transmission. The accumulator 73 accumulates the supplied hydraulic oil and supplies it to a hydraulic servomechanism (not shown), and prevents the accumulated hydraulic oil from flowing back to the oil pump 50-3 side. A backflow prevention valve 64 and a control circuit 72 into which high-pressure hydraulic oil accumulated in the accumulator 62 is introduced are provided. The accumulator 62 is provided with a hydraulic pressure sensor (pressure detection means) 63 for detecting the internal pressure.

  A shift valve (discharge path switching means) 65 for switching the discharge path of the hydraulic oil discharged from the oil pump 50-3 is installed on the downstream side of the oil pump 50-3. One of the switching destinations of the shift valve 65 is the lubrication circuit 71, and the other is the pressure accumulation circuit 73. The hydraulic control device 60 also includes an ECU (control means) 75 for controlling the hydraulic pressure supplied by the oil pump 50-3. Specifically, the ECU 75 controls switching of the shift valve 65, driving of the electric motor 10, and operation of the oil pump 50-3. The detection value of the hydraulic sensor 63 is output to the ECU 75.

  In the hydraulic control device 60, when the lubricating oil needs to be supplied to the operation mechanism unit of the transmission, the discharge path of the oil pump 50-3 is switched to the lubricating circuit 71 by the shift valve 65, and the electric motor 10 is turned on. The oil pump 50-3 is driven at low torque and high rotation by rotating in the forward direction. Hereinafter, this operation mode is referred to as a lubrication mode. On the other hand, when the pressure accumulation is required for the pressure accumulation circuit 73, the discharge path of the oil pump 50-3 is switched to the pressure accumulation circuit 73 by the shift valve 65, and the electric motor 10 is rotated in the reverse direction to Drive with high torque and low rotation. Hereinafter, this operation mode is referred to as a pressure accumulation mode.

  FIG. 9 is a graph showing output characteristics (hydraulic characteristics) of the hydraulic control device 60 of the present embodiment. The horizontal axis in the graph of the figure is the rotational speed of the oil pump 50-3, and the vertical axis is the input torque (discharge pressure) of the oil pump 50-3. As shown in the figure, the hydraulic control device 60 of the present embodiment satisfies two different pump characteristics: a high pressure and small capacity indicated by the area E on the graph and a low pressure and large capacity indicated by the area F. Is possible. That is, in the above-described lubrication mode, by driving the oil pump 50-3 with low torque and high rotation, the pump rotation speed can be increased and low pressure and large capacity can be realized. On the other hand, in the above pressure accumulation mode, by driving the oil pump 50-3 with high torque and low rotation, the input torque of the oil pump 50-3 can be increased and high pressure and low capacity can be realized.

  In addition, the dotted line shown in the graph of FIG. 9 does not use the accessory drive device 1 included in the hydraulic control device 1 of the present embodiment, but drives the oil pump with only a single electric motor, and the above two types of required characteristics. It is a graph which shows the output characteristic of the said oil pump when trying to satisfy | fill. In the hydraulic control device 60 according to the present embodiment, two different hydraulic characteristics can be obtained by the two types of output characteristics output from the speed change mechanism 20, so that two different pump characteristics of high pressure and small capacity and low pressure and large capacity are satisfied. It becomes possible. In addition, the electric motor 10 can be operated with high efficiency.

  As described above, the hydraulic control device 60 according to the present embodiment has a simple configuration including the single electric motor 10 and the single oil pump 50-3, but two different types of high pressure and small capacity and low pressure and large capacity. The pump characteristics can be satisfied, and the electric motor 10 can be operated with high efficiency.

  FIG. 10 is a graph showing changes in the internal pressure of the accumulator 62 in the hydraulic control device 60. The horizontal axis of the graph in FIG. 4 is the elapsed time T, and the vertical axis is the internal pressure Pacc of the accumulator detected by the hydraulic sensor 63. FIG. 11 is a flowchart showing a hydraulic control procedure in the hydraulic control device 60. The procedure of hydraulic control in the hydraulic control device 60 will be described with reference to the graph of FIG. 10 and the flowchart of FIG. First, it is determined whether or not the current operation of the hydraulic control device 60 is in the lubrication mode (step ST1-1). As a result, if it is not the lubrication mode (if it is the pressure accumulation mode) (NO), it is subsequently determined whether or not the internal pressure Pacc of the accumulator 62 is higher than the second threshold value P2 (pressure accumulation completion pressure) (step ST1- 2). As a result, when the internal pressure Pacc is lower than the second threshold value P2 (NO), the operation is performed in the pressure accumulation mode. On the other hand, when the internal pressure Pacc is higher than the second threshold value P2 (YES), the pressure accumulation mode is changed to the lubrication mode (step ST1-3).

  On the other hand, if the lubrication mode is selected in the previous step ST1-1 (YES), it is subsequently determined whether or not the internal pressure Pacc of the accumulator 62 is lower than the predetermined pressure P3 (step ST1-4). The predetermined pressure P3 is a pressure for determining whether or not to change the operating condition of the oil pump 50-3. As a result, when the internal pressure Pacc is higher than the predetermined pressure P3 (NO), the operation conditions of the oil pump 50-3 are not changed and the operation is continued. On the other hand, if the internal pressure Pacc is lower than the predetermined pressure P3 (YES), it is subsequently determined whether or not the internal pressure Pacc is lower than a first threshold P1 (pressure accumulation mode transition pressure) (step ST1-5). As a result, if the internal pressure Pacc is higher than the first threshold value P1 (NO), that is, if P1 <Pacc <P3, the oil pump 50-3 is increased so that the amount of lubricating oil supplied to the lubricating circuit 71 is increased. Are changed (step ST1-6). Specifically, the change of the operating conditions here is to increase the discharge amount of the oil pump 50-3 by increasing the rotation speed of the electric motor 10. On the other hand, if the internal pressure Pacc of the accumulator 62 is lower than the first threshold value P1 (YES), the operation of the hydraulic control device 60 is changed from the lubrication mode to the pressure accumulation mode (step ST1-7).

  That is, in the hydraulic control device 60 according to the present embodiment, when the engine (not shown) mounted on the vehicle is stopped, the operation of the hydraulic control device 60 is set to the lubrication mode, thereby ensuring the lubricating performance necessary for the lubrication circuit 71. To do. During normal control, the lubrication mode is selected according to the requirements of a transmission (not shown) (in balance with a mechanical oil pump driven by the rotation of the crankshaft of the engine). During the operation in the lubrication mode, when the internal pressure Pacc of the accumulator 62 decreases due to leakage or the operation of the hydraulic servo mechanism as indicated by the symbol G in the graph of FIG. 10 and reaches the first threshold value P1, the hydraulic control device 60 Is switched to the pressure accumulation mode. During operation in the pressure accumulation mode, the supply of lubricating oil to the lubricating circuit 71 is stopped. Therefore, it is necessary to supply a large amount of hydraulic oil to the lubrication circuit in advance. Therefore, immediately before switching to the pressure accumulation mode, when the internal pressure Pacc of the accumulator 62 drops to a predetermined pressure P3 (a pressure for changing the operating conditions of the oil pump 50-3) that is slightly larger than the first threshold value P1, the lubricating circuit 71 The operating condition of the oil pump 50-3 is changed so that the amount of the lubricating oil supplied to the oil pump is increased. That is, the operating state of the electric motor 10 is changed so that the discharge amount of the oil pump 50-3 increases more than before until a predetermined period (t0) immediately before switching from the lubrication circuit 71 to the pressure accumulation circuit 73. Thereby, the lubrication performance of the lubrication circuit 71 after changing to the pressure accumulation mode can be ensured.

  Thus, in the hydraulic control device 60 of the present embodiment, when the internal pressure Pacc of the accumulator 62 becomes higher than the second threshold value P2, the shift valve 65 is switched to lubricate as the discharge destination of the oil pump 50-3. While the circuit 71 is selected, when the internal pressure Pacc of the accumulator 62 becomes lower than the first threshold value P1, the pressure accumulation circuit 73 is selected as the discharge destination of the oil pump 50-3 by switching the shift valve 65. In addition, during a predetermined period (t0) immediately before the discharge destination of the oil pump 50-3 is switched from the lubrication circuit 71 to the pressure accumulation circuit 73, the electric motor 10 is configured to increase the discharge amount of the oil pump 50-3 more than before. Change the operating state of.

  In view of the usage pattern, the hydraulic control device 60 according to the present embodiment is in the middle of selecting the pressure accumulation circuit 73 as the discharge destination of the oil pump 50-3 depending on the vehicle (system) to be applied (during the pressure accumulation mode). Middle) may also require lubrication of the lubrication circuit 71. As a countermeasure for this, the above configuration increases the amount of hydraulic oil supplied to the lubrication circuit 71 immediately before the transition from the lubrication mode to the pressure accumulation mode. Thereby, the lubrication request | requirement with respect to the lubrication circuit 71 at the time of the pressure accumulation circuit 73 being selected can be satisfy | filled. Therefore, as in the prior art, the occurrence of problems such as seizure of operating parts in the transmission is prevented without causing an increase in the size of the device and a significant increase in energy consumption due to measures such as increasing the pressure during pressure accumulation. Is possible. Further, since the amount of lubrication can be minimized while the hydraulic oil is being supplied to the lubrication circuit 71 (during the normal lubrication mode), energy consumption can be reduced.

  FIG. 12 is a graph showing changes in the internal pressure Pacc of the accumulator 62 in the hydraulic control device 60. FIG. 13 is a flowchart showing another procedure of hydraulic control in the hydraulic control device 60. In the hydraulic control device 60 of the present embodiment, in addition to the above-described control, if the ECU 75 determines that the lubrication circuit 71 needs a larger amount of hydraulic oil than the normal flow, the accumulated pressure is accumulated. The second threshold value P2 that is the threshold value of the internal pressure Pacc of the accumulator 62 that transitions from the mode to the lubrication mode can be changed. Specifically, the second threshold value P2 is changed to a smaller value P2 ′ so that the pressure accumulation mode can be shortened and the transition to the lubrication mode can be made quickly.

  The procedure of hydraulic control in this case will be described with reference to the graph of FIG. 12 and the flowchart of FIG. First, it is determined whether or not the current operation of the hydraulic control device 60 is in the lubrication mode (step ST2-1). As a result, if it is not the lubrication mode (if it is the pressure accumulation mode) (NO), it is subsequently determined whether or not there is a request for increasing the lubrication amount (step ST2-2). As a result, if there is no request for increasing the lubrication amount (NO), it is determined whether or not the internal pressure Pacc of the accumulator 62 is higher than the second threshold value P2 (lubrication mode transition pressure) (step ST2-3). As a result, when the internal pressure Pacc is lower than the second threshold value P2 (NO), the operation is performed in the pressure accumulation mode. On the other hand, when the internal pressure Pacc is higher than the second threshold value P2 (YES), the pressure accumulation mode is changed to the lubrication mode (ST2-4). On the other hand, if there is a request for increasing the lubrication amount in the previous step ST2-2 (YES), it is determined whether or not the internal pressure Pacc of the accumulator 62 is higher than the second threshold value P2 ′ (accumulation pressure completion pressure) (step). ST2-5). As described above, the second threshold value P2 ′ here is a value different from the second threshold value P2, and is a value satisfying P2 ′ <P2. As a result, when the internal pressure Pacc of the accumulator 62 is lower than the second threshold P2 ′ (NO), the operation is performed in the pressure accumulation mode. On the other hand, when the internal pressure Pacc is higher than the second threshold P2 ′ (YES), the pressure accumulation mode is changed to the lubrication mode (ST2-6).

  On the other hand, if the lubrication mode is selected in the previous step ST2-1 (YES), it is subsequently determined whether or not the internal pressure Pacc of the accumulator 62 is lower than a predetermined pressure P3 (operating condition changing pressure of the oil pump 50-3). (Step ST2-7). As a result, when the internal pressure Pacc is higher than the predetermined pressure P3 (NO), the operation is performed in the lubrication mode. On the other hand, if the internal pressure Pacc is lower than the predetermined pressure P3 (YES), it is subsequently determined whether or not the internal pressure Pacc is lower than a first threshold value P1 (pressure accumulation mode transition pressure) (step ST2-8). As a result, if the internal pressure Pacc is higher than the first threshold value P1 (NO), that is, if P1 <Pacc <P3, the oil pump 50-3 is increased so that the amount of lubricating oil supplied to the lubricating circuit 71 is increased. Are changed (step ST2-9). Specifically, the change of the operating conditions here is to increase the discharge amount of the oil pump 50-3 by increasing the rotation speed of the electric motor 10. On the other hand, if the internal pressure Pacc of the accumulator 62 is lower than the first threshold value P1 in step ST2-8 (YES), the operation of the hydraulic control device 60 is changed to the pressure accumulation mode (step ST2-10).

  The graph of FIG. 12 shows the change in the internal pressure Pacc when the second threshold P2 is changed to P2 ′ (P2 ′ <P2). As shown in the graph of the figure, when the second threshold value P2 is changed to P2 ′, the duration time of the pressure accumulation mode is shortened (tβ → tα). Therefore, when the load on the drive system of the vehicle increases and the demand for lubrication becomes higher than normal (when there is a demand for increasing the amount of hydraulic oil to the lubrication circuit 71), the threshold value P2 is changed to P2 ′. The duration of the pressure accumulation mode can be shortened. Thereby, since it can be made to change to lubrication mode early, the lubrication performance of the operation mechanism part of a transmission can be secured.

  Note that, here, when there is a request for increasing the lubrication amount, the second threshold value P2 is changed to P2 ′. However, in addition to this, although the illustration is omitted, the first threshold value P1 is set. It is also possible to change to a higher value. Also by this, since the pressure accumulation mode can be shortened and the lubrication mode can be lengthened, the lubrication performance of the operation mechanism portion of the transmission can be ensured.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. FIG. 14 is a schematic diagram (partially skeleton diagram) showing a configuration of a hydraulic control device 60-4 according to the fourth embodiment of the present invention. FIG. 15 is a velocity diagram of the auxiliary machine driving device 1-2 included in the hydraulic control device 60-4. The hydraulic control device 60-4 of the present embodiment is different from the hydraulic control device 60 of the third embodiment in the configuration of the accessory drive device. That is, the hydraulic control device 60 of the third embodiment includes the auxiliary machine drive device 1 of the first embodiment, whereas the hydraulic control device 60-4 of the present embodiment is an auxiliary device of the second embodiment. The machine drive device 1-2 is provided. Other configurations are the same as those of the hydraulic control device 60 of the third embodiment.

  In the hydraulic control device 60-4 according to the present embodiment, as in the hydraulic control device 60 according to the third embodiment, the shift is performed during lubrication (lubrication mode) when lubrication oil needs to be supplied to the operation mechanism of the transmission. The discharge path of the oil pump 50-3 is switched to the lubrication circuit 71 by the valve 65. At that time, in the hydraulic control device 60 of the third embodiment, the electric motor 10 is driven in the forward direction, whereas in the hydraulic control device 60-4 of the present embodiment, the electric motor 10 is driven in the reverse direction. To do. As a result, the oil pump 50-3 is driven at low torque and high rotation. On the other hand, when pressure accumulation is required for the pressure accumulation circuit 73 (accumulation mode), the discharge path of the oil pump 50-3 is switched to the pressure accumulation circuit 73. At that time, in the hydraulic control device 60 of the third embodiment, the electric motor 10 is driven in the reverse direction, whereas in the hydraulic control device 60-4 of the present embodiment, the electric motor 10 is driven in the forward direction. To do. Thereby, the oil pump 50-3 is driven at high torque and low rotation.

  Similar to the hydraulic control device 60 of the third embodiment, the hydraulic control device 60-4 of the present embodiment has a simple configuration including the single electric motor 10 and the single oil pump 50-3, and the high pressure control device 60-4 has a high pressure. It is possible to satisfy two different types of pump characteristics, that is, a small capacity and a low pressure and a large capacity, and it is possible to operate the electric motor 10 with high efficiency.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible.

1, 1-2 Auxiliary machine drive device 10 Electric motor 20 Transmission mechanism 21 Input shaft 22 Output shaft 23 Casing (fixed-side member)
25 1st one-way clutch 27 2nd one-way clutch 50 Auxiliary machine (control target)
50-3 Oil pump (hydraulic pump: auxiliary machine)
60, 60-4 Oil pressure control device 61 Oil tank 62 Accumulator 63 Oil pressure sensor (oil pressure detecting means)
64 Backflow prevention valve 65 Shift valve (Discharge path switching means)
71 Lubricating circuit 72 Control circuit 73 Pressure accumulating circuit PT Planetary gear mechanism S Sun gear (first element, third element)
R ring gear (3rd element, 1st element)
C carrier (2nd element)
P pinion gear

Claims (7)

An auxiliary machine drive device comprising an electric motor and a transmission mechanism having a planetary gear mechanism capable of changing the rotation of the electric motor, and driving an auxiliary machine with an output from the transmission mechanism,
The electric motor can switch between forward and reverse rotation directions,
The planetary gear mechanism includes a first element coupled to an input shaft to which a driving force of the electric motor is input;
A third element connected to an output shaft for outputting a driving force to the auxiliary machine;
A second element meshing with the first element and the third element;
A first one-way clutch provided between the first element and the third element;
A second one-way clutch provided between the second element and the fixed member,
When the electric motor rotates in the forward direction, power is transmitted through a first transmission path in which the first one-way clutch operates in the planetary gear mechanism, and a driving force having a first characteristic is output from the output shaft. While
When the electric motor rotates in the reverse direction, power is transmitted through a second transmission path in which the second one-way clutch operates in the planetary gear mechanism, and a second characteristic different from the first characteristic is output from the output shaft. A driving apparatus having the characteristics described above is output. The planetary gear mechanism is a single pinion type planetary gear mechanism,
The first element is a sun gear fixed to the input shaft, the third element is a ring gear fixed to the output shaft, and the second element includes a pinion gear meshing with the sun gear and the ring gear. The accessory driving device according to claim 1, wherein the accessory driving device is a carrier having a carrier. The planetary gear mechanism is a single pinion type planetary gear mechanism,
The first element is a ring gear fixed to the input shaft, the third element is a sun gear fixed to the output shaft, and the second element has a pinion gear meshing with the sun gear and the ring gear. The accessory driving device according to claim 1, wherein the accessory driving device is a carrier having a carrier. A hydraulic pump that supplies hydraulic oil to a transmission mounted on a vehicle, and a drive device that drives the hydraulic pump,
The drive device is an accessory drive device according to any one of claims 1 to 3,
The hydraulic pump outputs a first hydraulic characteristic corresponding to the driving force having the first characteristic output from the driving device, and the first hydraulic pressure corresponding to the driving force having the second characteristic. A hydraulic control apparatus characterized in that a second hydraulic characteristic different from the characteristic is output. The discharge path for discharging the hydraulic oil from the hydraulic pump includes a lubrication circuit for lubricating the transmission and a pressure accumulation circuit for accumulating the discharged hydraulic oil with an accumulator and sending it to a control circuit for shift control. Divided into routes,
A discharge path switching means for switching between the lubrication circuit and the pressure accumulation circuit;
When the lubrication circuit is selected by the discharge path switching means, the first hydraulic characteristic is output from the hydraulic pump by rotating the electric motor forward.
The said 2nd hydraulic characteristic is output from the said hydraulic pump by reversely rotating the said electric motor when the said pressure accumulation circuit is selected by the said discharge path switching means. Hydraulic control device. Oil pressure detecting means for detecting the oil pressure of the hydraulic oil accumulated in the accumulator;
Control means for controlling the hydraulic pressure supplied by the hydraulic control device in accordance with the hydraulic pressure detected by the hydraulic pressure detection means,
The control means includes
When the detection value of the oil pressure detection means is lower than the first threshold value, the discharge path switching means switches from the lubrication circuit to the pressure accumulation circuit and switches from the lubrication circuit to the pressure accumulation circuit. In a predetermined period immediately before performing, the operating state of the electric motor is changed so as to increase the discharge amount of the hydraulic pump than before,
The switching from the pressure accumulation circuit to the lubrication circuit is performed by the discharge path switching unit when the detection value of the hydraulic pressure detection unit is higher than a second threshold value. Hydraulic control device. The control means has a function of determining the amount of lubrication necessary for the lubrication circuit,
In the control means, when it is determined to increase the amount of lubrication to the effect that a larger amount of lubrication than usual is required for the lubrication circuit,
The hydraulic control device according to claim 6, wherein the second threshold value for switching from the pressure accumulation circuit to the lubrication circuit is changed to another lower threshold value.

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