JP2005220997A - Oil cooling device of automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil cooling device for an automatic transmission capable of constructing an oil pump in a small size by reducing the leak amount of lubricating oil at a control valve. <P>SOLUTION: The oil cooling device of the automatic transmission is structured so that an oil cooler is installed just in front of the control valve, so as to reduce the leak amount inside the control valve of the oil heated in the oil pump, and thereby the rate of flow of the oil in consumption is reduced. This allows making the pump in small size, enhancing the fuel economy, and accomplishing a small and light construction of the automatic transmission. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus for cooling oil supplied to an automatic transmission.

  The automatic transmission is supplied with lubricating oil to prevent wear and seizure. This lubricating oil absorbs frictional heat from gears and stirs it in oil pumps, torque converters, and transmission mechanisms, resulting in high temperatures and a decrease in viscosity. To do.

Therefore, as a technique for cooling the lubricating oil, Patent Document 1 describes a hydraulic control device for an automatic transmission equipped with an oil cooler.
JP 2003-287124 A

  However, this technique has the following problems.

  Lubricating oil cooled by an oil cooler installed upstream of the oil pan generates heat by stirring the belt or gear in the oil pan. After that, when the lubricating oil in the oil pan is sucked by the oil pump, a leak from the discharge side to the suction side occurs in the gap between the pump gear and the pump housing, and heat is further generated by shearing of the lubricating oil. As a result, the temperature of the lubricating oil further increases, the viscosity decreases, and the amount of oil leaking from the gap between the valve body and the spool increases in the control valve on the downstream side of the oil pump.

  When the amount of leakage increases, a larger amount of discharge is required, and when the amount of discharge increases, the pressure loss of the discharge path increases. Therefore, the oil pump is required to have a pressure higher by this pressure loss.

  Therefore, the size of the oil pump is increased, the fuel consumption is deteriorated, and the automatic transmission is increased in size.

  The present invention has been made paying attention to such a conventional problem, and the oil cooling of an automatic transmission that enables downsizing of an oil pump by reducing the leakage amount of lubricating oil in a control valve. The object is to provide a device.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention includes an automatic transmission that is operated by hydraulic pressure and shifts according to a traveling state, an oil pump (1) that pumps hydraulic oil to the automatic transmission, and hydraulic oil that is pumped from the oil pump (1). A control valve (3) for supplying the automatic transmission to the automatic transmission, and a first control valve disposed upstream of the control valve (3) for cooling the working oil pumped from the oil pump (1). The oil cooler (2) is provided.

  As described above, the oil is pumped by the oil pump, the temperature rises, and the viscosity decreases. Therefore, in the present invention, the first oil cooler provided upstream of the control valve is cooled as described above. As a result, the oil passes through the control valve in a high viscosity state, and the amount of oil leaking from the gap between the valve body and the spool in the control valve can be reduced. Therefore, the oil consumption flow rate can be reduced and the pump can be downsized. Further, since the discharge amount can be reduced by downsizing the pump, the pressure loss in the discharge path can be reduced, and the hydraulic pressure generated accordingly can be lowered. By reducing the size of the pump and reducing the generated hydraulic pressure, it is possible to improve fuel efficiency and reduce the size and weight of the automatic transmission.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a hydraulic control system when the present invention is applied to a belt type continuously variable transmission. The solid line in the figure indicates the flow of hydraulic pressure, and the dotted line indicates the control line.

  The CVT system includes an oil pump 1, a first oil cooler 2, a control valve 3, a second oil cooler 4, and a speed change mechanism 5.

  The oil pump 1 is driven by the output of the engine 6. The oil pump 1 sucks and pressurizes the oil stored in the oil pan 7 and then pumps it to the control valve 3 through the first oil cooler 2. Dust and metal powder are removed from the oil sucked into the oil pump 1 from the oil pan 7 by the strainer 8.

  The first oil cooler 2 is provided between the oil pump 1 and the control valve 3 and cools the oil generated by the oil pump 1 before being pumped to the control valve 3. Here, since the viscosity of the oil is increased by cooling the oil, the amount of oil leak in the control valve 3 can be reduced.

  The control valve 3 controls the flow rate (hydraulic pressure) of the oil increased in pressure by the oil pump 1 and supplies the oil to the primary pulley 9, the secondary pulley 10, the torque converter 11, and the clutch 12. The control valve 3 is controlled by a CVT control unit (CVT C / U) 15. All the oil supplied to each part finally flows to the second oil cooler 4.

  The second oil cooler 4 cools the oil that has passed through the control valve 3 before supplying the oil to the portion of the transmission mechanism 5 that requires lubrication or cooling. Here, by cooling the oil, it is possible to maintain the necessary lubrication and cooling capacity in the transmission mechanism 5 even when the torque converter 11 generates a large amount of heat at the time of starting or stalling.

  The transmission mechanism 5 is mainly composed of a primary pulley 9, a secondary pulley 10, and a steel belt 13. The groove width of the primary pulley 9 and the secondary pulley 10 is changed by the hydraulic pressure fed from the control valve 3. The steel belt 13 is wound around the primary pulley 9 and the secondary pulley 10, and the gear ratio is changed by changing the pulley contact radius according to the groove width of each pulley.

  The driving force of the engine 6 is input to the transmission mechanism 5 by the input shaft 21 that is the rotation shaft of the primary pulley 9 and is output from the output shaft 22 that is the rotation shaft of the secondary pulley 10. In the input shaft 21, a torque converter 11 and a clutch 12 are disposed between the engine 6 and the primary pulley 9. The torque converter 11 converts the drive torque of the engine 6 with oil, and the clutch 12 switches the drive force of the engine 6 between forward and reverse of the vehicle.

  Since this speed change mechanism 5 has many movable parts, the oil cooled by the second oil cooler 4 is guided and lubricated and cooled as described above.

  The oil used for lubrication and cooling in the transmission mechanism 5 returns to the oil pan 7 and is sucked again by the oil pump 1.

  The engine 6 that drives the oil pump 1 is controlled by an engine control module (ECM) 14. Further, an accelerator opening sensor 16 that measures the accelerator opening, a rotation sensor 17 that detects the rotation speed of the primary pulley 9, a rotation sensor 18 that detects the rotation speed of the secondary pulley 10, and an oil that measures the temperature of the oil. The temperature sensor 19 is provided, and these detected values are transmitted to the CVT C / U 15. The CVT C / U 15 controls the hydraulic pressure supplied to the primary pulley 9, the secondary pulley 10, the torque converter 11 and the clutch 12 by controlling the control valve 3 based on these signals, thereby controlling the gear ratio. The CVT C / U 15 communicates with the ECM 14 via a CAN (Controller Area Network).

  Hereinafter, the operation of the CVT system of this embodiment will be described. In order to facilitate understanding, first, problems of the prior art will be described in detail. FIG. 4 is a schematic configuration diagram of a conventional oil cooling device for a belt-type continuously variable transmission. In addition, the same code | symbol is attached | subjected to the part which fulfill | performs the same function as embodiment of this application mentioned above, and the overlapping description is abbreviate | omitted.

  There is no conventional oil cooling device corresponding to the first oil cooler 2 of the present application, and the oil discharged from the oil pump 1 is sent to the control valve 3 without being cooled. Then, it is sent from the control valve 3 to the belt pulleys 9 and 10, the torque converter 11, and the clutch 12, cooled by the oil cooler 20, lubricated each part in the transmission mechanism, and then returned to the oil pan 7.

  However, such a configuration has a problem as shown in FIG. In the graph shown in FIG. 5, the vertical axis indicates the oil temperature, the horizontal axis indicates the path length from the strainer, and the part corresponding to the path length is described.

  That is, when oil is sucked into the oil pump 1 from the oil pan 7 through the strainer 8 (L1), the oil is stirred by the oil pump 1 to generate heat and the oil temperature rises (L2). It is sent from the valve 3 to the belt pulleys 9 and 10, the torque converter 11, and the clutch 12. If the oil temperature remains elevated, the oil viscosity is low as shown in the block of FIG. As the leakage amount increases, a larger discharge amount is required, so that the pump capacity needs to be increased. However, when the pump capacity increases, the discharge pressure loss of the oil pump 1 increases. Although these increase the hydraulic torque, the mechanical loss torque increases, the drive torque of the oil pump 1 increases, and the fuel efficiency deteriorates. In particular, this tendency was more remarkable in a belt type continuously variable transmission having a high hydraulic pressure and a large required flow rate.

  Therefore, in the present application, as described above, the first oil cooler 2 is disposed between the oil pump 1 and the control valve 3 so that the oil generated by the oil pump 1 is cooled before being fed to the control valve 3. It was.

  The operation of the present application will be described along the graph of FIG. In order to facilitate understanding, the oil temperature transition line in the conventional apparatus is shown by a broken line in the graph of FIG. Similarly to FIG. 5, the vertical axis and the horizontal axis indicate the oil temperature on the vertical axis, the path length from the strainer on the horizontal axis, and the part corresponding to the path length.

  In FIG. 2, the initial value of the oil temperature indicates the temperature of the oil passing through the strainer.

  Between L1 and L2, the oil is sucked and pressurized by the oil pump 1, a leak from the discharge side to the suction side occurs in the gap between the pump gear and the pump housing, and the oil temperature rises due to the shearing of the lubricating oil.

  The oil temperature hardly changes between L2 and L3, and the oil temperature is lowered by the first oil cooler 2 between L3 and L4, so that the oil temperature is lowered to near the temperature before passing through the oil pump 1.

  Between L4 and L5, the oil passes through the control valve 3, and a part of the oil is used as a pulley pressure and a clutch pressure. During this time, the oil temperature hardly changes.

  Between L5 and L6, the oil is cooled by the second oil cooler 4, and the oil temperature further decreases.

  The oil temperature hardly changes between L6 and L7, and between L7 and L8, the oil is supplied to the parts that require lubrication and cooling of the transmission mechanism 5 and generates heat due to metal friction and stirring.

  Thereafter, the oil returns to the oil pan 7 and repeats the above actions (L1 to L8).

  That is, when the oil is sucked into the oil pump 1 from the strainer 8 (L1), the oil is stirred to generate heat and the oil temperature rises (L2). However, the first oil cooler newly provided in the present application is used. After the temperature of the oil was lowered at 2 (L3 to L4), the oil was sent from the control valve 3 to the belt pulleys 9, 10, the torque converter 11, and the clutch 12. Since the oil temperature of the oil is lowered by the first oil cooler 2 as described above, the viscosity of the oil increases as shown by the block in FIG. Therefore, the amount of oil leakage at the control valve 3 or the like can be reduced. If the leak amount can be reduced, the pump capacity can be reduced, and the discharge pressure loss of the oil pump 1 can also be reduced. And since hydraulic torque can be reduced by these and a mechanical loss torque can also be reduced, the drive torque of the oil pump 1 can be reduced and a fuel consumption can be raised by extension.

  As described above, in the present embodiment, since the first oil cooler 2 is newly provided on the discharge side of the oil pump 1 and on the upstream side of the control valve 3, the oil temperature of the oil generated by the oil pump 1 is lowered to reduce the viscosity. The oil can be supplied to the control valve 3 after increasing the pressure. Therefore, the amount of oil leaking from the gap between the bubble body in the control valve 3 and the spool can be reduced.

  Also in the clutch 12 and the torque converter 11 disposed downstream of the control valve 3 and upstream of the second oil cooler 4, a seal portion between the shaft and the clutch drum, a seal portion of the clutch piston, and a pump shaft The amount of oil leakage from the seal portion of the fitting portion can be reduced.

  Therefore, since the oil consumption flow rate can be reduced, the oil pump 1 can be reduced in size, fuel efficiency can be improved, and the CVT system can be reduced in size and weight.

  Further, the pump size is reduced, so that the discharge amount of the oil pump 1 is reduced and the pressure loss in the discharge passage can be reduced. Therefore, the generated oil pressure is lowered by that amount, and the load on the oil pump 1 is reduced. Can be improved. Here, FIG. 3 shows the relationship between the hydraulic pressure generated by the oil pump 1 and the oil flow rate. As is apparent from FIG. 3, the oil pressure that needs to be generated by the oil pump can be reduced by reducing the required flow rate of the oil.

  Furthermore, the second oil cooler 4 is also provided in the present embodiment at the same position as the oil cooler 20 shown in FIG. 4 showing the prior art, so that the amount of heat generated by the torque converter 11 increases at the time of start or stall. Even if the temperature rises, the oil is cooled and then supplied to the transmission mechanism 5 downstream, so that the oil can maintain sufficient lubrication and cooling capability in the transmission mechanism 5. Here, by making the sum of the cooling capacities of the first oil cooler 2 and the second oil cooler 4 equal to the cooling capability of the oil cooler 20 of the prior art, the load required for the oil coolers 2 and 4 of the present invention is conventionally increased. Can be equivalent.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea, and it is obvious that these are equivalent to the present invention.

  For example, the belt type continuously variable transmission has been described in the present embodiment, but the present invention may be applied to a toroidal continuously variable transmission, a stepped automatic transmission, or the like.

  Further, the second oil cooler 4 corresponding to the conventional oil cooler 20 may not be provided. In this case, by making the cooling capacity of the first oil cooler 2 equal to the cooling capacity of the oil cooler 20 of the prior art, sufficient lubrication and cooling capacity can be maintained in the lubricating portion of the transmission mechanism.

It is a schematic block diagram which shows the hydraulic control system of the belt-type continuously variable transmission to which this invention is applied. It is explanatory drawing which showed the oil temperature transition of the oil in the apparatus of FIG. It is the comparison figure which showed the relationship between the flow volume of an oil pump and generated hydraulic pressure. It is a schematic block diagram which shows the hydraulic control system of the conventional belt-type continuously variable transmission. It is explanatory drawing which showed the oil temperature transition of the oil in the apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oil pump 2 1st oil cooler 3 Control valve 4 2nd oil cooler 5 Transmission mechanism 6 Engine 7 Oil pan 8 Strainer 9 Primary pulley 10 Secondary pulley 11 Torque converter 12 Clutch 13 Steel belt 14 Engine control module (ECM)
15 CVT control unit (CVT C / U)
16 Accelerator opening sensor 17 Rotation sensor 18 Rotation sensor 19 Oil temperature sensor 20 Oil cooler 21 Input shaft 22 Output shaft

Claims (6)

An automatic transmission that operates by hydraulic pressure and shifts according to the driving state;
An oil pump for pumping hydraulic oil to the automatic transmission;
A control valve for controlling the flow rate of hydraulic oil pumped from the oil pump and supplying the automatic transmission to the automatic transmission;
A first oil cooler that is disposed upstream of the control valve and that cools hydraulic oil pumped from the oil pump;
An oil cooling device for an automatic transmission, comprising: A second oil cooler for cooling the working oil downstream of the control valve;
The lubricating part of the automatic transmission introduces and lubricates the oil cooled by the second oil cooler,
The oil cooling device for an automatic transmission according to claim 1. The control valve is composed of a valve body, a spool and a spring.
The oil cooling device for an automatic transmission according to claim 1 or 2, wherein A clutch disposed coaxially with an input shaft for transmitting driving force to the automatic transmission;
The oil pressurized by the oil pump is pumped to the clutch through the first oil cooler.
The oil cooling device for an automatic transmission according to any one of claims 1 to 3, characterized in that: A torque converter disposed coaxially with an input shaft for transmitting driving force to the automatic transmission;
The oil pressurized by the oil pump is pumped to the torque converter via the first oil cooler.
The oil cooling device for an automatic transmission according to any one of claims 1 to 4, characterized in that: The automatic transmission is
A primary pulley and a secondary pulley whose groove width is changed by hydraulic pressure;
A belt that is wound around the primary pulley and the secondary pulley, and a pulley contact radius changes according to the groove width;
A belt type continuously variable transmission having
The oil cooling device for an automatic transmission according to any one of claims 1 to 5, characterized in that:

Images