JP2008256187A - Oil level adjusting device for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a relatively inexpensive oil level adjusting device 20 for properly adjusting the level of the oil surface of operating oil in an automatic transmission 2 as required. <P>SOLUTION: The oil level adjusting device comprises a catch tank 21 for receiving operating oil from the automatic transmission 2, a recirculation path 22 for returning the operating oil from the catch tank 21 to the automatic transmission 2, and a changeover valve 23 installed in the midway of the recirculation path 22. Receiving signal pressure P<SB>c2</SB>outputted when establishing a high shift stage with a range changeover hydraulic control circuit 7 of the automatic transmission 2, the changeover valve 23 closes the recirculation path 22. When the high shift stage is selected in this way, the operating oil cannot be returned from the catch tank 21 to the automatic transmission 2, therefore reducing the level of the oil surface in the automatic transmission 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an oil level adjusting device that adjusts the oil level of hydraulic oil in an automatic transmission mounted on a vehicle, for example, as necessary.

  In general, in an automatic transmission mounted on a vehicle, hydraulic oil stored in an oil pan is sucked out by an oil pump and supplied to an appropriate part. Returned.

  Conventionally, the reference level of the hydraulic oil stored in the automatic transmission has been defined as an amount that prevents the oil pump from sucking air at the cold temperature of the hydraulic oil and that the supply of the lubricating oil to the portion requiring lubrication is necessary and sufficient. The

  The volume of the hydraulic oil decreases when the temperature decreases, and increases when the temperature increases. Here, there is a concern that the friction loss in the automatic transmission increases when the volume of the hydraulic oil increases as the temperature of the hydraulic oil increases and the oil level in the automatic transmission increases.

  In view of this, there has been considered a device that adjusts the level so as to suppress an increase in the oil level when the temperature of the hydraulic oil in the automatic transmission is increased (see, for example, Patent Document 1).

  This device is provided with a distribution valve in the middle of an oil cooling circuit for cooling the hydraulic oil in the automatic transmission, and an oil reservoir to which hydraulic oil is supplied from the distribution valve at a high temperature is installed outside the automatic transmission. In some cases, the oil reservoir is provided with a reflux path for returning the hydraulic oil to the oil pan of the automatic transmission via a return valve.

  The distribution valve is, for example, an electrically controlled solenoid valve, and the solenoid valve is controlled by a controller as necessary. The return valve is of a type that uses a bimetallic valve element that opens and closes according to the temperature of the hydraulic oil.

  As for the operation, the oil level of the hydraulic oil in the oil pan is changed by operating the distribution valve with the controller and switching it as the temperature of the hydraulic oil rises, so that the hydraulic oil is supplied to the oil reservoir through the supply path. To prevent it from becoming high. On the other hand, when the hydraulic oil level drops, the return valve automatically opens and returns the hydraulic oil in the oil reservoir from the return path to the oil pan. Is prevented from becoming low.

  In this prior art, it is necessary to install an oil reservoir outside the automatic transmission, so that the installation work is troublesome. In addition, since a distribution valve and a return valve are necessary, the number of parts increases and the equipment cost increases. be pointed out.

  In contrast, in an oil cooling circuit for cooling the hydraulic oil in the automatic transmission, a control valve is provided in the middle of the reflux path, and an oil reservoir to which the hydraulic oil is supplied from the control valve through the supply path as needed is provided. There is one that is installed in an automatic transmission and returns hydraulic oil from the oil reservoir to an oil pan of the automatic transmission through a drain port of a control valve (see, for example, Patent Document 2).

The control valve is one of two springs made of shape memory alloy and automatically compresses or expands the shape memory alloy spring according to the temperature of the hydraulic oil to operate to the oil reservoir. The type is switched to a mode in which oil is supplied and a mode in which hydraulic oil is returned from the oil reservoir to the oil pan.
JP-A-5-33853 JP-A-2005-273880

  By the way, in the conventional example which concerns on the said patent document 1, a control valve and a return valve are required, and in the conventional example which concerns on the said patent document 2, the spring with which a control valve is provided is formed with an expensive shape memory alloy. As a result, the equipment cost for adjusting the oil level is increased.

  An object of the present invention is to provide an oil level adjusting device that adjusts the oil level of hydraulic oil in an automatic transmission to an appropriate level as required, at a relatively low cost.

  The present invention relates to an oil level adjusting device that adjusts the oil level of hydraulic oil in an automatic transmission as necessary, and includes a catch tank that receives hydraulic oil in the automatic transmission, and hydraulic oil in the catch tank. Including a return path for returning to the automatic transmission and a switching valve installed in the middle of the return path, and the switching valve establishes a high shift stage by a hydraulic control circuit for range switching provided in the automatic transmission The reflux path is closed when receiving a signal pressure that is output during the operation.

  According to this configuration, when the high gear position of the automatic transmission is established, the switching valve closes the return path so that the hydraulic oil cannot be returned from the catch tank to the automatic transmission side. It is possible to reduce the oil level height of the hydraulic oil in the transmission to a predetermined minimum level lower than the reference level.

  On the other hand, when the low speed stage of the automatic transmission is established, the switching valve opens the return path, allowing the hydraulic oil to naturally flow out from the catch tank. Only between the oil level adjusting device and the oil level adjusting device, the oil level of the hydraulic oil in the automatic transmission is maintained at a predetermined reference level.

  In the first place, for example, when the low gear stage is established, the hydraulic oil in the automatic transmission often has a relatively low temperature, so by keeping the oil level of the hydraulic oil at a relatively high reference level, It is preferable to avoid air suction of the oil pump in the automatic transmission.

  However, when the high gear is established, the hydraulic oil pressure increases and the volume of the hydraulic oil increases due to the relatively high temperature of the hydraulic oil in the automatic transmission. Since the oil level of the hydraulic oil tends to increase, the friction loss in the automatic transmission tends to increase.

  In such a case, according to the above configuration of the present invention, the switching valve closes the return path, so that the hydraulic oil in the catch tank cannot be returned to the automatic transmission side. Therefore, the oil level of the hydraulic oil in the automatic transmission is reduced to the minimum level, and it is possible to reduce friction loss in the automatic transmission.

  Thus, paying attention to the fact that there is a correlation between the selection state of the shift stage of the automatic transmission and the level of the hydraulic oil temperature in the automatic transmission, the automatic transmission can be switched from the low shift stage to the high shift stage. In the above process, the hydraulic oil is not stored in the catch tank, that is, it is allowed to pass through, so that the oil level height of the hydraulic oil in the automatic transmission is kept at the reference level, while at the high shift stage, The hydraulic oil is stored in the catch tank and lowered to the minimum level.

  If the switching valve is simply hydraulically operated as in the oil level adjusting device of the present invention, it is possible to use a general-purpose product that is generally available easily and inexpensively.

  In addition, since the signal pressure for establishing a high gear stage, which is inevitably used in the hydraulic control circuit of the automatic transmission, is used as the operating pressure of the switching valve, the hydraulic oil in the automatic transmission is used as in the conventional example. A system for monitoring the temperature is not required, an operation control system for the switching valve is not required, and an expensive switching valve having a spring made of a shape memory alloy is not required.

  For this reason, it is possible to reduce the equipment cost of the oil level adjusting device and the equipment cost of an automatic transmission that uses the equipment.

  Preferably, the supply of the hydraulic oil to the catch tank is configured to use the action of lifting the hydraulic oil by the rotating body in the automatic transmission.

  According to this configuration, a special power source for supplying hydraulic oil to the catch tank is not required, and the hydraulic oil circulation path from the oil pump provided in the automatic transmission is changed as in the conventional example. This configuration is unnecessary. Therefore, it is advantageous in reducing the equipment cost of the oil level adjusting device and the equipment cost of the automatic transmission using the oil level adjusting device.

  Preferably, the hydraulic control circuit of the automatic transmission is configured to engage and release friction engagement elements such as various clutches and brakes provided in the transmission mechanism of the automatic transmission when the target shift stage is established. The switching valve outputs a signal pressure, and the switching valve is connected to an existing spool type valve involved in the establishment of a high gear stage in the hydraulic control circuit, on the upstream side and the downstream side of the intermediate separation portion in the return path. It is assumed that two ports connected to and are added.

  The intermediate separation portion in the reflux path is a region where the switching valve is intervened in the reflux path. The upstream side and the lower end side of the halfway separation portion are based on the flow direction of the hydraulic oil returned from the catch tank to the automatic transmission.

  According to this configuration, since an existing spool type valve having two additional ports is used as the switching valve, the configuration can be simplified as compared with the conventional example. Therefore, it is possible to reduce the equipment cost of the oil level adjusting device.

  Preferably, the switching valve is of a normally open type in which the valve body is disposed at a position where the return passage is opened by the biasing force of the spring in a natural state, and the biasing force of the spring is applied when the signal pressure is applied. Accordingly, the valve body is displaced to a position that closes the reflux path.

  In short, the normally open type switching valve is a generally known simple and inexpensive general-purpose product, which is advantageous in reducing the equipment cost of the oil level adjusting device.

  According to the above configuration, for example, when the low gear is selected, the switching valve opens the return path and allows the hydraulic oil to naturally flow out from the catch tank. Is selected, the switching valve closes the return path so that the hydraulic oil does not flow out of the catch tank.

  ADVANTAGE OF THE INVENTION According to this invention, the oil level adjustment apparatus which adjusts the oil level height of the hydraulic fluid in an automatic transmission to an appropriate level as needed can be provided comparatively cheaply.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. First, FIG. 1 to FIG. 6 show an embodiment of the present invention.

  Here, prior to the description of the features of the present invention, an outline of an automatic transmission that is an object of use of the oil level adjusting device according to the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram showing a power train of a vehicle including an automatic transmission to be used by an oil level adjusting device according to the present invention, and FIG. 2 shows an example of a transmission mechanism unit in the automatic transmission of FIG. FIG. 3 is a skeleton diagram and FIG. 3 is an engagement table of the clutches C1 and C2, brakes B1 to B3, and the one-way clutch F1 at each shift stage of the transmission mechanism unit in FIG.

  In the figure, 1 is an engine, 2 is an automatic transmission 2 and a control device.

  The engine 1 has a crankshaft 1 a connected to the input shaft of the torque converter 5 of the automatic transmission 2.

  The automatic transmission 2 shifts and outputs the rotational power input from the engine 1, and in this embodiment, for example, is a type that is mounted on an FF (front engine / front drive) type vehicle.

  The automatic transmission 2 mainly includes a torque converter 5 with a lock-up clutch 5a, a transmission mechanism unit 6, a hydraulic control circuit 7, and the like.

  The components of the automatic transmission 2 are basically known configurations and will be briefly described.

  The control device 3 controls the operations of the engine 1 and the automatic transmission 2 in an integrated manner, and is a generally known ECU (Electronic Control Unit) including a CPU, a ROM, a RAM, a backup RAM, and the like.

  The control device 3 controls at least the engagement pressure of the lock-up clutch 5a of the torque converter 5 and also controls various valves provided in the hydraulic control circuit 7 of the automatic transmission 2 so that the automatic transmission 2 Controls shifting operation.

  As shown in FIG. 2, the speed change mechanism unit 6 mainly includes a front planetary 11, a rear planetary 12, clutches C1 and C2, brakes B1 to B3, a one-way clutch F1, and the like. A one-stage shift is possible.

  The front planetary 11 is a single pinion type planetary gear mechanism, and includes a sun gear S1, a ring gear R1, a pinion gear P1, and a carrier CA1.

  The rear planetary 12 is a planetary gear mechanism called a ravinio type, which has a small-diameter sun gear S2, a large-diameter sun gear S3, a ring gear R2, a plurality of short pinion gears PS, and a plurality of long pinion gears PL. And the carrier CA2.

  Note that. The first clutch C1, the second clutch C2, the first brake B1, the second brake B2, and the third brake B3 are all friction engagement elements that are engaged or released by hydraulic pressure.

  Then, the power transmission of the front planetary 11 and the rear planetary 12 is achieved by engaging or releasing the first clutch C1, the second clutch C2, the first brake B1, the second brake B2, the third brake B3, and the one-way clutch F1. By selecting a route, an appropriate gear position (1st to 6th gears) is established.

  For example, FIG. 3 shows an engagement table for explaining engagement and disengagement states of clutches and brakes for establishing each gear position of the automatic transmission 2. In the figure, “◯” represents engagement, and “x” represents release.

  As shown in FIG. 3, in the automatic transmission 2, the first shift stage (1st) is established by engaging the first clutch C1. The upshift from the first gear (1st) to the second gear (2nd) is performed by further engaging the first brake B1 while the first clutch C1 is engaged.

  In the upshift from the second speed (2nd) to the third speed (3rd), the first brake B1 is released and the third brake B3 is engaged while the first clutch C1 is engaged. Is done by.

  In the upshift from the third gear (3rd) to the fourth gear (4th), the third brake B3 is released and the second clutch C2 is engaged while the first clutch C1 is engaged. Is done by.

  In the upshift from the fourth speed (4th) to the fifth speed (5th), the first clutch C1 is released and the third brake B3 is engaged while the second clutch C2 is engaged. Is done by.

  In the upshift from the fifth shift speed (5th) to the sixth shift speed (6th), the third brake B3 is released and the first brake B1 is engaged while the second clutch C2 is engaged. Is done by.

  The reverse speed (Rev) is established by engaging both the second brake B2 and the third brake B3.

  The hydraulic control circuit 7 is based on the hydraulic oil supplied from an oil pump (not shown) driven by the crankshaft 1 a of the engine 1 based on an appropriate shift command signal given from the control device 3. A signal pressure for engaging or releasing the first clutch C1, the second clutch C2, the first brake B1, the second brake B2, and the third brake B3 is generated.

  Next, portions to which the features of the present invention are applied will be described in detail with reference to FIGS.

  4 is a diagram schematically showing the internal configuration of the automatic transmission of FIG. 1, FIG. 5 is a sectional view showing the configuration of an embodiment of the switching valve in the oil level adjusting device of FIG. 4, and FIG. It is a circuit block diagram which shows typically a level adjustment apparatus and a part of hydraulic control circuit.

  The automatic transmission 2 described above is provided with an oil level adjusting device 20 for adjusting the oil level of the hydraulic oil inside.

  As shown in FIG. 4, the oil level adjusting device 20 includes a catch tank 21, a reflux path 22, and a switching valve 23.

  The catch tank 21 is installed above the oil level of the hydraulic oil in the automatic transmission 2 and stores a predetermined amount of hydraulic oil.

  The reflux path 22 is a path for returning the hydraulic oil from the catch tank 21 to the oil pan 2 a of the automatic transmission 2.

  The switching valve 23 is installed in the middle of the recirculation path 22 and opens or closes the recirculation path 22 as necessary to allow or block the flow of hydraulic oil.

  Note that hydraulic oil in the automatic transmission 2 is supplied into the catch tank 21 in an appropriate form.

  The supply form of the hydraulic oil to the catch tank 21 is, for example, a form in which the hydraulic oil is lifted up by a rotating body 2b such as an appropriate gear provided in the automatic transmission 2.

  As shown in FIG. 5, the switching valve 23 is configured such that a valve body 26 and a reverse spring 27 are housed in a valve case 25.

  The valve case 25 is provided with a signal input port 25a, an inflow port 25b, and a drain port 25c. An appropriate operating pressure is applied to the signal input port 25a. The inflow port 25b is connected to the upstream side of the intermediate separation part in the reflux path 22, and the drain port 25c is connected to the downstream side of the intermediate separation part in the reflux path 22, respectively.

  The switching valve 23 is a so-called normally open type. That is, the normally open type is such that the valve body 26 is shown in the left half of FIG. 5 with the urging force of the reverse spring 27 in a natural state where an appropriate operating pressure is not applied to the signal input port 25a. In this case, the inflow port 25b is opened and the reflux path 22 is opened by being arranged on the lower side in FIG. At this time, since the catch tank 21 and the oil pan 2a are in communication with each other, the hydraulic oil outflow from the catch tank 21 to the oil pan 2a is allowed.

  When an appropriate operating pressure is applied to the signal input port 25a of the switching valve 23, the valve body 26 is moved against the urging force of the reverse spring 27 as shown in the right half of FIG. By disposing, the inflow port 25b is closed and the reflux path 22 is closed. At this time, since the catch tank 21 and the oil pan 2a are in a non-communication state, the hydraulic oil cannot move from the catch tank 21 to the oil pan 2a.

As shown in FIG. 6, the operating pressure applied to the switching valve 23 is a signal pressure P _C2 for engaging the second clutch C2 output from the second linear solenoid valve SLC2 described below in the hydraulic control circuit 7.

This signal pressure P _C2 , as already described with reference to the engagement table of FIG. 3, is established when the high gear (the fourth gear 4th, the fifth gear 5th and the sixth gear 6th) is established. It is always output from the second linear solenoid valve SLC2.

As described above, in order to enable the signal pressure P _C2 output from the second linear solenoid valve SLC2 to be applied to the signal input port 25a of the switching valve 23, the following configuration is provided.

  In the hydraulic control circuit 7 shown in FIG. 6, a branch path 34 is provided on the upstream side of the communication path 33 that communicates the second linear solenoid valve SLC2 described below and the clutch control valve 31 of the failsafe circuit 30. The switching valve 23 is connected to the signal input port 25a.

  Here, the configuration of the hydraulic control circuit 7 will be described with reference to FIG. FIG. 6 shows only a part of the configuration related to the present invention in the hydraulic control circuit 7 and will be specifically described below.

  As shown in FIG. 6, the hydraulic control circuit 7 includes at least a first linear solenoid valve SLC1, a second linear solenoid valve SLC2, a third linear solenoid valve SLB3, and a fail safe circuit 30.

  In addition, the hydraulic control circuit 7 includes various valves although not shown because it is not related to the characteristic part of the present invention.

As this valve, for example, as is well known, a manual valve that is operated by a shift lever to output a drive range pressure (P _D ), a reverse range pressure (P _R ), etc., or a pressure of hydraulic oil supplied from an oil pump is known. The primary regulator valve, SL solenoid valve, SLU linear solenoid valve, SLT linear solenoid valve, and line pressure (P _L ) that regulates the pressure of the circuit and outputs the main line pressure (P _L ) of the circuit, the SL solenoid valve , SLU linear solenoid valve and SLT linear solenoid valve, etc., solenoid modulator valve that outputs the original pressure (P _MOD ), linear solenoid valve SLB1 that controls the first brake B1, B2 apply control valve that controls the second brake B2, and B2 Control bar Breakfast, and the like.

The first linear solenoid valve SLC1 receives the drive range pressure P _D is output from the manual valve (not shown), and outputs the signal pressure P _C1 of the first clutch C1 engaged, appropriate input in the fail-safe circuit 30 Enter the port.

The second linear solenoid valve SLC2 is subjected to drive range pressure P _D is output from the manual valve (not shown), a second output a signal pressure P _C2 of the clutch C2 engaging, appropriate input in the fail-safe circuit 30 Enter the port.

The third linear solenoid valve SLB3 receives the line pressure (P _L ), outputs a signal pressure P _B3 for engaging the third brake B3, and inputs it to an appropriate input port in the failsafe circuit 30.

  In short, the fail-safe circuit 30 includes all linear solenoid valves SLC1, SLC2 for outputting the original pressure of the engagement signal pressure supplied to the first clutch C1, the second clutch C2, the first brake B1, and the third brake B3, respectively. , SLB1 and SLB3 are configured to take an appropriate measure when an off-fail that the original pressure is not output occurs, and includes a clutch control valve 31 and a sequence valve 32.

  In addition, as the countermeasure, for example, when the off-fail occurs at the time of starting the vehicle, a predetermined gear stage is established to enable the start, or when the off-fail occurs during the traveling of the vehicle, for example, In order to maintain the above, a mode in which a predetermined shift speed is established, and the like are exemplified.

  Both of these valves 31 and 32 are spool type valves, and a spool valve body (not shown) is arranged at a predetermined position by reverse springs 35 and 36 in a non-operating state.

In FIG. 6, the hydraulic pressure P _SLT input to the sequence valve 32 is output from the SLT linear solenoid valve (not shown).

  Next, the operation will be described.

First, after the engine 1 is started, when the range of the automatic transmission 2 is the neutral position N and the parking position P, or when the drive position D is selected, the low gear (the first gear 1st, the first gear When the second gear 2nd and the third gear 3rd are selected, the operating pressure (signal pressure P _C2 ) is not input to the signal input port 25a of the switching valve 23.

  Therefore, the switching valve 23 is kept in a normally open state. That is, since the switching valve 23 keeps the inflow port 25b open, the inflow port 25b and the drain port 25c are kept in communication, that is, the reflux path 22 is kept open.

  In this state, since the hydraulic oil can naturally flow out from the catch tank 21, the hydraulic oil circulates between the oil pan 2 a and the oil level adjusting device 20. The oil level of the hydraulic oil is maintained at a predetermined reference level.

On the other hand, when the high shift speed (the fourth shift speed 4th, the fifth shift speed 5th, and the sixth shift speed 6th) is selected while the drive position D is selected, the signal input port 25a of the switching valve 23 is activated. Pressure (signal pressure P _C2 ) is input.

  Therefore, the switching valve 23 closes the inflow port 25b, and the inflow port 25b and the drain port 25c are in a non-communication state, that is, the reflux path 22 is closed. In this state, the hydraulic oil cannot be returned from the catch tank 21 to the oil pan 2a side, so that the oil level of the hydraulic oil in the automatic transmission 2 is lowered to a predetermined minimum level.

Here, the reason why the operating pressure for the switching valve 23 described above is the signal pressure P _C2 output from the second linear solenoid valve SLC2 will be described.

  First, in the situation where the low speeds (first speed 1st, second speed 2nd, and third speed 3rd) are selected in the automatic transmission 2, each part of the speed change mechanism 6 is operated by being driven at a low speed. The oil temperature tends not to rise very much. Therefore, when the low gear position is selected, the oil level of the hydraulic oil in the automatic transmission 2 is set to a predetermined level for the purpose of preventing air suction of an oil pump (not shown) of the automatic transmission 2. It can be said that the reference level is preferable.

  On the other hand, in the situation where the high speed stage (the fourth speed stage 4th, the fifth speed stage 5th, and the sixth speed stage 6th) is selected in the automatic transmission 2, the speed change mechanism portion 6 is driven at a high speed to The temperature tends to rise.

  Thus, when the hydraulic oil temperature in the automatic transmission 2 rises, the volume of the hydraulic oil increases and the oil level rises. Therefore, when the high gear is selected, the automatic transmission is configured such that the hydraulic oil supplied into the catch tank 21 cannot be returned to the oil pan 2a for the purpose of reducing the friction loss in the automatic transmission 2. It can be said that it is preferable to set the oil level height of the hydraulic oil in 2 to a minimum level lower than the reference level.

  Thus, considering the fact that there is a correlation between the selection state of the shift stage of the automatic transmission 2 and the level of the hydraulic oil temperature in the automatic transmission 2, the operating pressure for the switching valve 23 is set as described above. It is specified.

  By the way, it is preferable that the reference level and the minimum level described above are appropriately set by experiment so as to satisfy the respective purposes as described above.

  As described above, according to the embodiment to which the feature of the present invention is applied, the operation in the automatic transmission 2 is performed in the situation where the low gear position in which the hydraulic oil in the automatic transmission 2 is relatively low is selected. By keeping the oil level at the reference level, it is possible to prevent air intake by an oil pump (not shown) of the automatic transmission 2 while the hydraulic oil in the automatic transmission 2 is at a high temperature. In a situation where a high gear position is selected, the friction loss in the automatic transmission 2 is reduced by reducing the oil level of the hydraulic oil in the automatic transmission 2 to a minimum level lower than the reference level. It becomes possible.

  Moreover, in the above embodiment, since the switching valve 23 of the oil level adjusting device 20 has a simple configuration that operates with hydraulic pressure, it can be a general-purpose product that is generally available at low cost.

Moreover, the signal pressure P _C2 output from the existing second linear solenoid valve SLC2 provided in the hydraulic control circuit 7 is used as the operating pressure for controlling the operation of the switching valve 23. This eliminates the need for a system for monitoring the operating oil temperature in the automatic transmission 2 as in the conventional example, and eliminates the need for an operation control system for the control valve.

  For these reasons, it is advantageous to reduce the equipment cost of the oil level adjusting device 20 and the equipment cost of the automatic transmission 2 using the same.

  In addition, this invention is not limited only to the said embodiment, All the deformation | transformation and application included in the range equivalent to the claim and the said range are possible. In the following, modifications and application examples will be described.

  (1) In the above-described embodiment, an example in which a dedicated switch valve 23 of the oil level adjusting device 20 is used is given. For the switch valve 23, for example, the hydraulic control circuit 7 shown in FIG. It is possible to divert the clutch control valve 31 of the fail safe circuit 30 provided in the above.

  Specifically, the clutch control valve 31 used as the switching valve 23 is provided with two ports 31a and 31b as shown in FIG. 7 in addition to the existing ports in the structure shown in FIG.

  Of these two new ports 31a and 31b, one is connected to the upstream side of the halfway separation portion in the reflux path 22, and the other is connected to the downstream side of the halfway separation portion in the reflux path 22.

  The two new ports 31a and 31b are switched to a communication state or a non-communication state depending on a displacement position of a spool valve body (not shown) of the clutch control valve 31.

Here, for example, when the operating pressure (the signal pressure P _C2 output from the second linear solenoid valve SLC2) is applied to the clutch control valve 31, the spool valve body has a predetermined resistance against the urging force of the reverse spring 35. Although it is displaced to a position, the two new ports 31a and 31b described above are set to be in a non-communication state at the displaced position.

  In this case as well, in the same manner as in the above embodiment, in the situation where the low gear position where the hydraulic oil in the automatic transmission 2 is relatively low is selected, the oil level of the hydraulic oil in the automatic transmission 2 is set to the reference level. In this situation, it is possible to prevent air intake by an oil pump (not shown) of the automatic transmission 2 while maintaining a high speed stage in which the hydraulic oil in the automatic transmission 2 becomes hot. Then, it is possible to reduce the friction loss in the automatic transmission 2 by reducing the oil level of the hydraulic oil in the automatic transmission 2 to a minimum level lower than the reference level.

  Moreover, as the switching valve 23 of the oil level adjusting device 20, the clutch control valve 31 provided in the hydraulic control circuit 7 is diverted to the two ports 31a and 31b, so that the configuration is simplified compared to the conventional example. Therefore, the equipment cost of the oil level adjusting device 20 can be reduced.

  (2) In the above embodiment, as an example of supplying the hydraulic oil in the automatic transmission 2 to the catch tank 21, an example in which the hydraulic oil pumping action by the rotating body 2b in the automatic transmission 2 is used is given. However, for example, it is possible to adopt a form as shown in JP-A-2005-273880, and such a form is also included in the present invention.

  In the above-mentioned patent document, in an oil cooling circuit for cooling hydraulic oil in an automatic transmission, a control valve is provided in the middle of a return path after cooling of hydraulic oil, and an oil reservoir is provided from the control valve to an oil reservoir as needed. Hydraulic oil is supplied. If necessary, the hydraulic oil is returned from the oil reservoir to the oil pan of the automatic transmission through the drain port of the control valve.

  In order to apply the present invention to such a configuration, for example, a return path of hydraulic oil from an oil reservoir to an oil pan is provided independently, and the above-described switching valve of the present invention is installed in the middle of the return path. It is possible to do.

  (3) In the above embodiment, an example is given in which the present invention is applied to the automatic transmission 2 of forward 6-speed shift. However, the present invention is not limited to this and is also applied to an automatic transmission having an arbitrary number of stages. Is possible.

  (4) In the above embodiment, the case where the present invention is applied to the automatic transmission 2 mounted on an FF (front engine / front drive) vehicle has been described. However, the present invention is not limited to this, and the FR (front It can also be applied to an automatic transmission mounted on an engine / rear drive vehicle or other type of vehicle.

It is a schematic block diagram which shows the power train of the vehicle containing the automatic transmission used as the usage object of the oil level adjustment apparatus which concerns on this invention. FIG. 2 is a skeleton diagram illustrating an example of a transmission mechanism unit in the automatic transmission of FIG. 1. FIG. 3 is an engagement table of clutches C1 and C2, brakes B1 to B3, and a one-way clutch F1 for each gear position of the transmission mechanism unit of FIG. It is a figure which shows typically the internal structure of the automatic transmission of FIG. FIG. 5 is a cross-sectional view illustrating a configuration of an embodiment of a switching valve in the oil level adjusting device of FIG. 4. FIG. 5 is a circuit configuration diagram schematically showing the oil level adjusting device of FIG. 4 and a part of a hydraulic control circuit. FIG. 7 is a view corresponding to FIG. 6, showing another embodiment of the switching valve in the oil level adjusting device of FIG. 4.

Explanation of symbols

1 engine
2 Automatic transmission
2a Automatic transmission oil pan
2b Rotating body in automatic transmission
3 Control device
6 Automatic transmission transmission mechanism
DESCRIPTION OF SYMBOLS 7 Hydraulic control circuit 20 Oil level adjusting device 21 Catch tank 22 Recirculation path 23 Switching valve 25a Signal input port 25b Inflow port 25c Drain port 26 Valve body 27 Reverse spring 30 Fail-safe circuit of hydraulic control circuit 31 Clutch control valve of fail-safe circuit 32 Sequence valve of fail-safe circuit C2 Second clutch of transmission mechanism SLC2 Second linear solenoid valve of hydraulic control circuit

Claims (4)

An oil level adjusting device that adjusts the oil level of hydraulic oil in an automatic transmission as required,
A catch tank for receiving hydraulic oil in the automatic transmission, a return path for returning the hydraulic oil in the catch tank to the automatic transmission, and a switching valve installed in the middle of the return path,
The switching valve is configured to close the return path when receiving a signal pressure output when a high shift stage is established by a hydraulic control circuit for range switching provided in the automatic transmission. Oil level adjustment device for automatic transmission. The oil level adjusting device for an automatic transmission according to claim 1,
The oil level adjusting device for an automatic transmission is characterized in that the supply of the hydraulic oil to the catch tank is configured to use the action of pumping up the hydraulic oil by a rotating body in the automatic transmission. The oil level adjusting device for an automatic transmission according to claim 1 or 2,
The hydraulic control circuit of the automatic transmission generates signal pressures for engaging and releasing various frictional engagement elements such as various clutches and brakes provided in the transmission mechanism portion of the automatic transmission when the target shift stage is established. Output
In the hydraulic control circuit, the switching valve has two ports that are connected to the upstream side and the downstream side of the intermediate separation portion in the reflux path, in addition to the existing spool type valve that is involved in the establishment of a high gear position. An oil level adjusting device for an automatic transmission, characterized in that The oil level adjusting device for an automatic transmission according to claim 1 or 2,
The switching valve is a normally open type in which the valve body is arranged in a position where the return path is opened in a natural state, and the valve body is displaced to a position where the return path is closed when the signal pressure is applied. An oil level adjusting device for an automatic transmission, characterized in that

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