JPH0392677A - Gear shift control method for automatic transmission for vehicle - Google Patents

Abstract

PURPOSE:To provide readiness during high speed running and to execute further smooth starting and continuous operation at a very low speed by a method wherein when a car speed is below a given value and an engine output exceeds a given value, a lowermost gear speed is prohibited. CONSTITUTION:An operation parameter is read and when a car speed V is below a given relatively low car speed V0 and a throttle opening theta of an engine exceeds a given relatively high opening theta0, a lowermost gear speed, i.e., a first gear speed, is prohibited, and shift of a speed based on the operation parameter is effected between a first gear speed a fifth gear speed. A high output engine is mounted, a lowermost gear speed having a high reduction gear ratio is provided, readiness during high speed running is provided, and further smooth starting and very low speed continuous operation are practicable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the control of an automatic transmission for a vehicle, and particularly to a method for controlling gear change.

[Prior Art] A vehicular automatic transmission that automatically switches a vehicular automatic transmission having a plurality of gears, such as in an automobile, according to the values of several parameters related to the driving state of the vehicle, such as vehicle speed and throttle opening. Many proposals have been made so far regarding speed change control methods for transmissions. The basic technical idea that is almost common to the shift control of these automatic transmissions for vehicles is to use the vehicle speed and a quantity representative of the amount of depression of the accelerator pedal as the basic parameters for determining the gear position of the automatic transmission. The gear position is determined based on the equilibrium relationship between the two. In other words, as the vehicle starts from a stopped state and gradually increases speed, the relative magnitude between the vehicle speed and the amount of accelerator pedal depression gradually increases as the former becomes larger compared to the latter. Several boundaries are set for the relative relationship, and the gear stage is switched in accordance with the boundaries.

By the way, in conventional automobiles equipped with general automatic transmissions, the number of forward gears is usually 3 to 4, which is sufficient to achieve a sufficiently smooth start and acceleration from a stopped state.
The reduction ratio at the lowest gear is set to a value not exceeding 3. However, in recent years, with the intensification of traffic congestion in urban areas, cars are often moving at extremely low speeds of several kilometers per hour, and even in the lowest gear with a conventional reduction ratio of 3 or less, it is difficult to stop the vehicle temporarily. In such cases, a gear with a higher reduction ratio is desired. Japanese Patent Application Publication No. 60-8824
Publication No. 9 states that in order to respond to continuous speed changes of the vehicle and obtain a reduction ratio appropriate from the viewpoint of fuel efficiency, rotational transmission efficiency, etc., the number of gears in 4-speed is too small. An automatic transmission that has five forward speeds by adding a gear mechanism that can selectively provide one more speed deceleration to the output side of the gear transmission mechanism that provides four forward speeds including the drive speed speed. It has been proposed to establish a mechanism. Such an automatic transmission is also suitable for continuous operation of a vehicle at extremely low speeds during road congestion as described above.

[Problem to be solved by the invention] However, in recent years, on the one hand, traffic congestion in urban areas has become increasingly severe, as described in 2. On the other hand, with the development of expressway networks, the number of automobiles has increased. As the speed of driving has increased, there has been a demand for higher output engines in automobiles so that they can quickly accelerate when overtaking, etc., even while driving at high speeds.

Therefore, on the one hand, the reduction ratio of the lowest gear of the automatic transmission is increased as described above, and on the other hand, when the engine output is increased, the automatic transmission is set to the lowest gear. When the accelerator pedal is fully depressed, an excessive 1.0 l lux is applied to the drive system from the automatic transmission to the wheels.

As described above, when the automatic transmission is multi-staged and the maximum reduction ratio is increased on the one hand, and the engine output is increased on the other hand, excessive torque is inadvertently applied to the drive system. The object of the present invention is to provide a shift control method for automatic transmissions for vehicles that is effective in dealing with the potential load and solving this problem.

[Means for Solving the Problem] According to the present invention, the above problem is solved by automatically changing the gears of an automatic transmission for a vehicle having a plurality of gears depending on the values of several parameters related to the driving state of the vehicle. The problem is solved by a method characterized in that the lowest gear is prohibited when the vehicle speed is below a predetermined value and the engine output is above a predetermined value.

[Action of the invention] If an engine with a higher output than the vehicle weight is installed,
It is possible to obtain greater acceleration when driving a vehicle, improving driving agility especially when driving at high speeds, but
Since rotational power is the product of torque and rotational speed, even if the engine output increases during medium to high speed operation of a vehicle where each rotating member of the drive system from the engine to the wheels rotates at a relatively high speed, the torque will increase. The absolute value of is not very large, and probably does not even reach the torque that acts on the drive system when starting a vehicle equipped with a conventional economical output engine and an automatic transmission with a maximum reduction ratio of 3 or less. . Therefore, according to the present invention, if the lowest gear is prohibited only when the vehicle speed is below a predetermined value and the engine output is above a predetermined value, even if the engine output is increased and the maximum deceleration is increased, It is possible to reliably prevent the torque acting on the drive system of the vehicle from becoming excessive.

As mentioned above, increasing the number of gears of an automatic transmission compared to that of a conventional general automobile and making the reduction ratio of the lowest gear even higher than that of a conventional general automobile, The purpose is to make the start of the vehicle smoother and to enable continuous operation at extremely low speeds during road congestion, and is not to increase the maximum torque that can be obtained from the drive system.
When the engine output is increased above a predetermined value while the vehicle speed is below a relatively low predetermined value, the lowest gear is prohibited, and the gear that is obtained at that time is made to be a higher gear. This is not in any way contrary to the main idea of increasing the number of gears and the reduction ratio of the lowest gear, but rather that an undesirable excessive torque acts on the drive system, and in order to cope with this, the drive system must be made heavier. This is an effective way to avoid this.

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

6. FIG. 1 is a schematic diagram showing an example of a transmission mechanism of an automatic transmission for a vehicle to which the automatic transmission control method according to the present invention is applied. In FIG. 1, P1 is one planetary gear mechanism, which includes a sun gear 10, a ring gear 12, a planetary pinion 14, and a carrier 16. Similarly, P2 is another planetary granite mechanism, and includes a Zangya 20, a ring gear 22, a planetary binion 24, and a carrier 26. The ring gear 2 of the planetary gear mechanism P1 is connected to the carrier 26 of the planetary gear mechanism P2 by a connecting element 3o, and the carrier 16 of the planetary gear mechanism PI is connected to the ring gear 22 of the planetary gear mechanism P2 by a connecting element 32. There is. Carrier 16 or connecting element 32
The ring gear 22 connected by a first one-way clutch (Fl) 34 and a second one-way clutch. (
F2) is connected to the housing 50 via a series connection of 36. One-way clutch 34 is its inner race 3
It is connected to the carrier 16 on the 4a side, and connected to the inner race 36a of the one-way clutch 36 via the connecting element 31 on the outer race 34b side.

An outer race 36b of the one-way clutch 36 is fixed to a housing 50. Both one-way clutches 34 and 36 are oriented so that they become engaged when torque is applied in the same direction, and released when torque is applied in the opposite direction. engage.

52 is an input shaft of this speed change gear mechanism. This human-powered shaft is selectively connected to the Zangya 20 by a first clutch (C,) 38, selectively connected to the carrier 16 by a second clutch (C2) 40, and selectively connected to the carrier 16 by a third clutch (C3).
42, and connects the outer race 34b of the one-way clutch 34 and the inner race 36a of the one-way clutch 36 by connecting the third clutch 42 and the fourth clutch (C4) 44 in series. 31.

The connecting element 3] is adapted to be selectively braked against the housing 50 by a first brake (B, ) 46. The combination of the carrier 16, the ring gear 22, and the connecting element 32 connecting them is selectively braked against the housing 5o by a second brake (B2) 48. A gear 54 is connected to the carrier 26,
A gear 62 is meshed with this gear.

P3 is a third planetary gear mechanism, which includes a sun gear 64, a ring gear 66, a planetary pinion 68, and a carrier 70. The sangya 64 and the carrier 70 are selectively connected to each other by a fifth clutch (C5) 56. Also, Zangya 64 has a third brake (
The housing 50 is selectively braked by B3) 58 and unidirectionally rotated by a third one-way clutch (F3) 60 which is oriented to automatically engage when the engine is running. The housing 50 is automatically braked only when χiJ is reached.

An output gear 72 is connected to the carrier 70 9 . Reference numeral 74 denotes a central support shaft that rotatably supports the third planetary gear mechanism P and its related rotating parts.

This gear transmission mechanism includes clutches C, C2, C3, C4,
C5, brakes B, B2, B3 are selectively engaged as shown in Table 1, and one-way clutches F, F2, F3 are automatically engaged as shown in Table 1. By doing so, the reduction ratio decreases sequentially from 1st speed to 5th speed.
A speed change gear and a reverse gear can be achieved. Furthermore, the first
In the table, O indicates that the corresponding clutch or brake is selectively engaged or the one-way clutch is automatically engaged at the corresponding gear stage. Further, (0) for the brake indicates that the gear position is achieved with the engine brake in effect when the brake is engaged.

] 0 11 The ratio of the number of teeth of the ring gear 10 to the number of teeth of the ring gear 2 in the planetary gear mechanism P1 is ρ1, and the planetary gear mechanism P
Sanghya 20 for the number of teeth of ring gear 22 in 2
Let the ratio of the number of teeth of the ring gear 66 in the planetary gear mechanism P3 be ρ2, and the ratio of the number of teeth of the sun gear 64 to the number of teeth of the ring gear 66 in the planetary gear mechanism P3 be ρ.
3, the reduction ratio at each gear stage is as shown in Table 2.

Table 2 further shows ρl = 0.401, ρ2-0.557
, ρ3 = 0.350, the reduction ratio values at each gear stage are shown.

1 2 13 The gear transmission mechanism shown in FIG. 1 consists of planetary gear mechanisms P and P2 shown in the upper half of the figure, and a clutch C.
1 to C4, brakes B and B2, and one-way clutches F1 and F2, and a planetary gear mechanism P3 and clutch C shown in the lower half of the figure.
It has a configuration in which a gear transmission mechanism consisting of a brake B3 and a one-way clutch F3 are connected in series. The gear transmission mechanism shown in the upper half of this figure is based on the patent application filed in 1983, filed earlier by the same applicant as the present applicant.
The structure has already been proposed in No. 5471, and an example of a hydraulic control device for operating such a gear transmission mechanism is also disclosed in Japanese Patent Application No. 1983-1982, filed earlier by the same applicant as the present applicant. It was proposed in No. 192966.

The gear transmission mechanism shown in the lower half of the figure has substantially the same structure as the gear transmission mechanism that has been used for a long time to provide an overdrive speed stage. As a gear transmission mechanism,
The carrier 70 was used as a manual member, and the ring gear 66 was used as an output member. When used as a conventional overdrive gear transmission mechanism, when using this in a direct connection state, the clutch C
, is engaged, brake B is released, and when this is to perform a speed increasing action, clutch C5 is released and sangya 64 is automatically braked by one-way clutch F3, or brake B3 is further engaged. Accordingly, rotation of the Sanghya 64 in both directions was braked. Such pressure control devices for reciprocal engagement and release of clutches and brakes are also well known in various forms, one example of which is disclosed in Japanese Patent Publication No. 58-22654 filed by the same applicant as the present applicant. It is shown in the official gazette. Therefore, it will be easy for those skilled in the art to operate the gear transmission mechanism as shown in FIG. 1 as a whole to achieve each gear in the manner shown in Table 1.

FIG. 2 is a diagram showing, in the form of a flowchart, the gist of the speed change control method for an automatic transmission according to the present invention.

When the shift control of the automatic transmission is disclosed in step 1, step 1 reads operating parameters that are information necessary for the shift control of the automatic transmission.

These operating parameters include shift ranges such as D, SSL, and RSN selected by the manual valve, vehicle speed, and engine output. In the illustrated embodiment, throttle opening is used as a parameter representative of engine output. Next, in step 2, it is determined whether the vehicle speed V is less than a predetermined relatively low vehicle speed, for example, a value of about 10 km/h. If the determination result is YES, the control process proceeds to step 3.

In step 3, the engine throttle opening O is set to a relatively large predetermined opening e. It is determined whether or not the value is greater than or equal to the value. If the determination result is YES, the control process proceeds to step 4. If the results in both steps 2 and 3 are negative, the control process proceeds to step 5.

In step 4, the lowest speed gear, that is, the first gear in the embodiment shown in Table 1 above, is prohibited, and the gear change based on the operating parameters is prohibited from the second gear to the first gear. This is done between 5th gear. When the control process reaches step 5, the lowest gear is not inhibited, and therefore, in the embodiment shown in Table 1, the gears are changed between the first gear and the fifth gear. This control process is repeated during vehicle operation via a return.

In the embodiment shown in FIG. 2, the determination as to whether or not the engine output is above a predetermined value is made based on the throttle opening, but there are other parameters representative of the engine output. , intake pipe negative pressure, intake air amount, etc. may be adopted.

[Effects of the Invention] Thus, according to the present invention, in controlling the gear shift of an automatic transmission for a vehicle, when the vehicle speed is less than a predetermined value and the engine output is greater than or equal to a predetermined value, the lowest gear is selected. By incorporating this as part of the speed change control, the vehicle is equipped with a high-output engine and has a lowest gear with a high reduction ratio, allowing for greater agility at high speeds, smoother starts, and ultra-low-speed continuous operation. A high performance automobile can be obtained without undesirably high torque loads on the drive system and correspondingly increased weight.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a gear shift mechanism of an automatic transmission suitable for applying the shift control method for an automatic transmission for a vehicle according to the present invention, and FIG. 2 is a schematic diagram showing a gear shift mechanism of an automatic transmission for a vehicle according to the present invention. 1 is a flowchart 1. showing one embodiment of a control method. P, , P2, P3... Planetary granite device, 10, 20,
64...Sanghya] 2, 22, 66...Ring gear 14, 24, 68・Planetary pinion 16, 26
, 70...Carrier, 30, 31, 32/Connecting element.
34, 36, 60... One-way clutch 38, 40,
42, 44, 56...Clutch 46, 48, 58...
...Brake, 52...Input shaft, 54, 62...Gear, 72...Output shaft, 74...Support shaft Patent issued
Applicant: 1 Yota Automobile Co., Ltd. Representative: Masaki Akashi, Patent Attorney 18 Figure 2

Claims (1)

[Claims] A method of automatically switching the gears of an automatic transmission for a vehicle having a plurality of gears according to the values of several parameters related to the driving state of the vehicle, when the vehicle speed is below a predetermined value and the engine output is a predetermined value. A method characterized in that the lowest speed gear is prohibited when the speed is equal to or higher than that.