JPH02292566A - Hydraulic control device for automatic transmission - Google Patents

Abstract

PURPOSE:To attain a speed change with an influence of centrifugal oil pressure considered by detecting a rotary speed of a clutch, engaged or disengaged when a speed is changed, and controlling an engaging pressure of the clutch through the dependence on at least the square of the speed of the clutch. CONSTITUTION:In order to adequately reflect an influence of centrifugal oil pressure to a control of the actual engaging pressure, a rotary speed of a clutch, engaged or released at the time of speed change, is detected by a speed sensor, and being based on the detection, an engaging pressure of the clutch is controlled by an engaging pressure control means through the dependence on at least the square of this rotary speed. Thus by accurately reflecting an influence of the centrifugal oil pressure, generated in proportion to the square of the rotary speed, to the clutch, a control of the clutch engaging pressure can be performed on the premise that the centrifugal oil pressure is generated. In this way, a speed change shock can be reduced by performing an adequate engaging control.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a hydraulic control device for an automatic transmission configured to reduce shift shock by controlling engagement pressure during gear shifting.

[Conventional technology]

A gear transmission mechanism and a plurality of frictional engagement devices are provided, and the plurality of frictional engagement devices are selectively engaged or released by operating a hydraulic control device to form an arbitrary gear stage. This automatic transmission is already widely known. In such an automatic transmission, the engagement pressure when the frictional engagement device engages or disengages, for example, the back pressure of an accumulator, is electronically controlled depending on various running conditions (running parameters) at that time. A technology has been proposed to reduce the shift shock as much as possible. For example, as an example of such hydraulic control,
14965, a technique is proposed in which this engagement pressure is controlled depending on the type of shift.

[Problem to be solved by the invention]

However, conventionally known engagement pressure control does not take into account the influence of centrifugal hydraulic pressure generated by the rotation of frictional engagement devices (particularly clutches) that are engaged or released during gear shifting. Due to the generation of centrifugal hydraulic pressure, there have been cases where the actual engagement pressure generated is higher than the intended engagement pressure. In other words, there are roughly two types of frictional engagement devices; one is a brake that fixes or allows a rotating member to rotate with respect to a fixed member (case), and the other is a brake that fixes or rotates a rotating member with respect to a fixed member (case). A clutch that engages (connects so that power can be transmitted) or disengages (disconnects so that power cannot be transmitted) rotating members with each other.
Therefore, due to the nature of the clutch, which is a frictional engagement device, when the clutch starts engaging, the case (drum) that was previously stopped starts rotating, or conversely, the case that was rotating until then stops. It will bend. As a result, for example, when the clutch gate starts rotating from a stopped state due to engagement, as the rotation speeds up, the centrifugal hydraulic pressure generated by the rotation of the clutch itself increases with the control hydraulic pressure supplied from the hydraulic control device. As a result, the actual engagement pressure becomes considerably higher than the control hydraulic pressure, and as a result, the shift is completed too early, causing a shift shock. In particular, in the past, the shift point of an automatic transmission was generally determined depending on the throttle opening and the speed, so the clutch rotation speed at the start or end of the shift depends on the type of shift. Therefore, as in the prior art described above, for example, by performing control such as multiplying each type of gear shift by a specific correction coefficient, it is possible to increase the As a result, we were able to reflect the influence of centrifugal hydraulic pressure to some extent. However, in recent years, it has become possible to perform so-called manual shifts over a wide range of automatic transmissions, and the same shift (type) is often performed at very different vehicle speeds. When such manual gear shifting comes to be performed, the number of revolutions of the clutch when shifting is carried out will also take on a very wide range of values, and centrifugal hydraulic pressure becomes effective at the square of this number of revolutions. However, there was a problem in that unless the actually generated centrifugal oil pressure was properly reflected in the engagement pressure control, the error from the optimum engagement pressure could become too large. In addition, whether manual or automatic shifting, automatic transmissions in recent years are required to have the ability to shift gears with smaller shift shocks, and therefore it is essential to perform even more precise engagement pressure control. It has come to be said that The present invention was made in view of such conventional problems, and regardless of whether the shift is manual or automatic, the influence of centrifugal hydraulic pressure that occurs or disappears as engagement progresses or disengagement progresses. Our goal is to provide a hydraulic control system for automatic transmissions that can further reduce shift shock by controlling the engagement pressure more appropriately and taking into account the above factors.

[Means to solve the problem]

The present invention provides a hydraulic control device for an automatic transmission that is configured to reduce shift shock by controlling engagement pressure during a shift, which includes: means for detecting the rotational speed of a clutch that is engaged or released during the shift; The above object is achieved by including means for controlling the engagement pressure of the clutch depending on at least the square of the rotation speed of the clutch.

[Effect]

In the present invention, in order to accurately reflect the influence of centrifugal oil pressure on the control of actual engagement pressure, the rotational speed of the clutch that is engaged or released during the gear shift is detected, and the engagement pressure of the clutch is adjusted to at least this rotation. The control depends on the square of the number. This is because centrifugal oil pressure is generated in proportion to the square of the clutch rotation speed. As a result, it is possible to accurately reflect the influence of the centrifugal oil pressure generated in the clutch, and the engagement pressure can be controlled based on the premise that this centrifugal oil pressure is generated, resulting in extremely precise engagement. Combined pressure control becomes possible. Note that the control considering the centrifugal oil pressure may be performed by detecting the rotation speed of the clutch in real time and controlling the engagement pressure during gear shifting in real time depending on the square of this rotation speed. The number of rotations is detected when the gear shift is started or when a predetermined time has elapsed since the shift is started, and corrections are made depending on the square of the detected number of rotations in subsequent engagement pressure control. It is also possible to have a configuration like this.

【Example】

Embodiments of the present invention will be described in detail below based on the drawings. In this embodiment, in order to control the engagement pressure of the frictional engagement device, the back pressure of the accumulator is controlled. In addition, clutch C2 generates centrifugal hydraulic pressure during gear shifting.
The structure is such that the centrifugal hydraulic pressure can be controlled in consideration of the shift involving the centrifugal hydraulic pressure, such as a 3-2 downshift or a 2-3 upshift. Figure 2 shows an overall outline of a vehicle automatic transmission to which this embodiment is applied. This automatic transmission includes a torque converter section 20 and an overdrive Il structure section 4 as its transmission sections.
0, and an underdrive mechanism section 60 with three forward stages and one reverse stage. The torque converter section 20 is a well-known one that includes a pump 2l, a turbine 22, a stator 23, and a lock-up clutch 24. The overdrive mechanism section 40 includes a set of planetary gears consisting of a sun gear 43, a ring gear 44, a planetary pinion 42, and a carrier 41, and the rotational state of this planetary gear is controlled by a clutch C.
It is controlled by O, brake Bo, and one-way clutch FO. The underdrive mechanism section 60 has a common sangya 6.
1, ring gear 62, 63, planetary pinion 64,
65 and carriers 66 and 67, and the rotational state of the two sets of planetary gear devices and the connection state with the overdrive mechanism are controlled by the clutch C1,
C2, brakes 81 to B3, and one-way clutch F+,
It is controlled by F2. Since this transmission part itself is well known,
Regarding the concrete connection state of each component, only a skeleton diagram is shown in FIG. 2, and detailed explanation will be omitted. This automatic transmission includes a transmission section as described above,
and a computer (ECU) 84. The computer 84 includes a throttle sensor 80 that detects the throttle opening degree θth to reflect the output (torque) of the engine 1, a vehicle speed sensor (rotational speed sensor of the output shaft 70) 82 that detects the vehicle speed no, and a rotational speed of the clutch C2. N. Each signal from the 02 rotation speed sensor 99, etc. that detects the rotation speed is input. The computer 84 controls the solenoid valve S+ in the hydraulic control circuit 86 according to a preset throttle opening/vehicle speed shift map.
It drives and controls S2 (for the shift valve) and SL (for the lock-up clutch), and performs the combination of engagement of each clutch, brake, etc. as shown in Fig. 3 to execute gear changes. FIG. 4 shows the main parts of the hydraulic control circuit 86.
In the figure, the reference numeral So indicates a hydraulic solenoid for performing hydraulic control taking into consideration centrifugal hydraulic pressure, 108 an accumulator control valve, 110 a modulator valve,
112 is an accumulator, and 114 is a shift valve. In this figure, a clutch C is used as a frictional engagement device.
2 is shown representatively. As is clear from FIG. 3, clutch C2 is involved (released or engaged) when achieving a town shift from 3rd gear to 2nd gear and an upshift from 2nd gear to 3rd gear. This is a frictional engagement device. Line pressure PL is created by a well-known method using oil pressure generated by an oil pump (not shown) as a base pressure. This line pressure P L is the boat l of the modulator valve 110.
applied to lOA. Modulator valve 110 receives this line pressure PL and generates a predetermined modulator pressure PLo in boat 110B using a well-known method. Linear solenoid SC) is connected to this modulator pressure PLo.
In response to this, a solenoid pressure PS+ is generated according to the square of the rotation speed NC2 of the clutch C2. That is, the computer 84
As mentioned above, the rotational speed NC2 of the clutch C2 is input to . When the rotation speed Nc2 of the clutch C2 is high, a large amount of centrifugal oil pressure is generated, so in order to reduce the control pressure of the clutch C2 by an amount corresponding to this, a load current corresponding to the square of the rotation speed NC2 is generated. is applied to the linear solenoid SO, which uses this load current to generate a solenoid pressure Psi proportional to the load current in a well-known manner. This solenoid pressure P S + is input to the boat 108A of the accumulator control valve 108. The accumulator control valve 108 receives as input signals the throttle pressure pth reflecting the engine torque and the solenoid pressure PS+ from the linear solenoid SO.
Adjust the line pressure PL2 of the boat 108B to the accumulator back pressure pac. That is, the accumulator back pressure pac is the line pressure P L 2 regulated by the throttle pressure pth, the solenoid pressure PS+, and the biasing force of the spring 108C, and as the solenoid pressure PS+ increases,
In other words, as the centrifugal oil pressure increases, the value becomes lower. Now, the third
This will be explained using an example of downshifting from gear to second gear. When the computer 84 determines a 3-2 downshift, the solenoid valve S1 is activated to open the clutch C2.
Shift valve 114 is switched in a well-known manner via C2, and line pressure PL<PC2) begins to drain from clutch C2. As a result, the piston 11 of the accumulator 112, which had been pushed up to the top of the figure by the line pressure PL (PC2) supplied to the clutch C2,
2A begins to descend. While the screws 1 to 112A are lowered, the oil pressure pcz applied to the clutch C2 is
The downward biasing force of the spring 112B and the piston 11
The hydraulic pressure will be maintained in balance with the downward force acting on 2A. The force pushing the piston 112A downward is generated by the accumulator back pressure Pac applied to the back pressure chamber 112C of the accumulator 112. As a result,
As described above, the accumulator back pressure Pac is applied to the throttle opening θ via the modulator valve 110, the linear solenoid So, and the accumulator control valve 108.
Since the control is dependent on th and the centrifugal oil pressure, it is possible to control the oil pressure PC2 when the clutch C2 is released to an oil pressure that takes the centrifugal oil pressure into account. By the way, for example, if the strong centrifugal hydraulic pressure generated during manual gear shifting is completely canceled out, the shift shock can be reduced extremely well, but this will lengthen the gear shifting time and reduce the durability of the clutch. It becomes a trend. Therefore, if centrifugal oil pressure is generated very strongly, it is best to avoid completely canceling it out and avoid making the shift time too long. Now, in the above embodiment, in order to take into account the centrifugal oil pressure related to the clutch C2, the rotation speed Nc of the clutch C2 is
2 was detected directly, so the rotation speed NC2 of clutch C2 was continuously monitored from the beginning to the end of the shift.
It was possible to perform accumulator backpressure control in real time depending on the square of the rotation speed Nc2. However, when performing such real-time control, it is naturally necessary to install a C2 sensor 99 to detect the rotation speed of clutch C2. However, this C
As is clear from the engagement diagram in Fig. 3, the installation of the two sensors 99 allows for speed change control that takes centrifugal oil pressure into consideration.
There is only a downshift from 3rd gear to 2nd gear and an upshift from 2nd gear to 3rd gear. Therefore, if such centrifugal oil pressure consideration control is applied to gear changes involving other clutches, such as upshifting from 3rd gear to 4th gear, and downshifting from 4th gear to 3rd gear, If you try to do this even during a shift, the relevant clutch Co.
It is necessary to further install a sensor to detect the rotation speed NGO. As is well known, there is almost no extra space inside an automatic transmission, so installing two new sensors is not only extremely difficult, but also increases cost. Therefore, in order to more easily perform the control according to the present invention, it is possible to adopt a configuration that utilizes the output value of the vehicle speed sensor (rotational speed sensor of the output shaft 70) 82 that detects the vehicle speed no. In other words, when a gear shift is achieved by releasing the clutch, in most cases the clutch will shift from the state where the most centrifugal oil pressure is generated to the state where the centrifugal oil pressure is zero. If you know the rotational speed of the clutch when it starts, you can roughly estimate its trajectory. The rotational speed of the clutch when the gear shift starts can be indirectly detected by calculation using the output value of the vehicle speed sensor 82 and a constant (for example, gear ratio) determined depending on the type of gear shift. . Therefore, it is predicted that the rotation speed of the clutch at the start of the shift, which is implicitly detected by calculation, will be zero by the time the shift ends, and the value at each point in this trajectory is calculated by By estimating that the centrifugal oil pressure is generated depending on the rotation speed, it becomes possible to perform control that is almost the same as canceling out the centrifugal oil pressure while detecting the rotation speed in real time. Similarly, when the clutch is released, the centrifugal oil pressure has the greatest effect at the moment when the clutch is engaged, that is, when the centrifugal oil pressure is at its maximum, and gear shifting is started. The centrifugal oil pressure, which is determined depending on the square of the rotation speed, is maintained as a "constant oil pressure" until the gear shift is completed.
It is also possible to have a configuration in which it continues to be added as . This method can also be applied to clutches whose centrifugal oil pressure does not become zero when released, and in practice, even with this configuration, the error will not be that large. This control will be explained in more detail with reference to FIG. In FIG. 6, the optimal control pressure PCL to be generated in the hydraulic control device is calculated by subtracting the centrifugal hydraulic pressure pY from the hydraulic pressure Px corresponding to the throttle opening θth, plus the hydraulic pressure Z corresponding to the return spring load of the piston in the clutch. Set it so that it is added. Since the accumulator is equipped with a spring, the accumulator back pressure Pac is determined by considering the hydraulic pressure PF corresponding to the load of the accumulator spring, and the drive current of the linear solenoid So is determined. It is advisable to set the hydraulic pressure PF for the accumulator spring load to be slightly smaller than the spring load when the accumulator makes a full stroke, so as not to receive sliding resistance from the O-ring of the accumulator piston. After the rotation speed of clutch C2 is calculated at the start of the shift, the accumulator back pressure PaC is fixed until the end of the shift. That is, according to this embodiment, after the shift starts, the progress of the shift is controlled only by the hydraulic jerk corresponding to the accumulator spring load. Even with this configuration, the characteristics when the clutch C2 is released are substantially influenced by the oil pressure value at the start of the gear shift, so this method can also provide a corresponding effect. By the way, when shifting is achieved by engagement of the clutch, in most cases the rotational speed of the clutch at the start of the shift is zero, and no centrifugal oil pressure is generated. Therefore, in order to take into account the influence of centrifugal oil pressure without providing a rotation speed sensor for the clutch when a gear shift is achieved by engaging the clutch, for example, a timer or the like can be used to determine the speed change after the gear shift has started. The number of rotations of the clutch at a predetermined time near the end of the shift is indirectly detected by calculation based on the output value from the vehicle speed sensor 82, and the centrifugal oil pressure is determined depending on the square of the indirectly detected number of rotations. can be configured to estimate that this will occur. With this configuration, centrifugal hydraulic pressure of the clutch can be corrected with extremely high accuracy during both downshifts and upshifts, without having to provide a separate rotation speed sensor for each clutch. As mentioned above, the correction taking into account the oil pressure is performed in proportion to the square of the rotation speed of the clutch, and the proportionality constant Y at this time is determined by the position of the clutch with respect to the center of rotation of the automatic transmission (rotation radius r). It is best to decide for each clutch depending on (see Figure 5). As a result, centrifugal hydraulic pressure is generated that is stronger for clutches located radially farther from the central axis of rotation of an automatic transmission, but it becomes possible to perform centrifugal hydraulic control that takes such installation locations into consideration.

[Effect of the idea]

As explained above, according to the present invention, in the case of a shift involving a clutch, engagement pressure control is performed after accurately considering the influence of centrifugal oil pressure generated by the rotation of the clutch itself, In particular, even in cases where a shift is performed from (or to) a shift point different from the conventional shift point, such as a manual shift, the influence of the centrifugal hydraulic pressure that actually occurs must be properly considered. This has the excellent effect of being able to perform gear changes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the gist of the present invention, and FIG. 2 is a block diagram showing the gist of the present invention.
A schematic block diagram of a vehicle self-transmission M machine to which an embodiment of the present invention is applied; FIG. 3 is a diagram showing the operating state of the frictional engagement device in the automatic transmission; FIG. A hydraulic circuit diagram showing the main parts of the hydraulic control system of the transmission, Fig. 5 is a diagram showing the relationship between the rotation speed of the clutch and the centrifugal oil pressure generated, and Fig. 6 is a diagram showing the relationship between the rotation speed of the clutch and the generated centrifugal oil pressure. It is a shift characteristic diagram when a downshift to a gear is performed. So...Linear solenoid, 108...Accumulator control valve, PA
C...Accumulator back pressure, Psi...Renoid pressure (2 of the rotation speed of clutch C2)
(hydraulic pressure corresponding to the vehicle), C2...clutch.

Claims (1)

[Claims] (1) In a hydraulic control device for an automatic transmission configured to reduce shift shock by controlling engagement pressure during a shift, means for detecting the rotational speed of a clutch that is engaged or released during the shift; A hydraulic control device for an automatic transmission, comprising means for controlling the engagement pressure of a clutch depending on at least the square of the rotational speed of the clutch.