JP3467938B2 - Engine brake control device for automatic transmission - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine brake control device for an automatic transmission.

[0002]

2. Description of the Related Art An automatic transmission determines a power transmission path (gear stage) of a gear transmission system by selectively hydraulically operating and engaging a plurality of gear shifting friction elements, but releases an accelerator pedal of an engine. If the engine brake is constantly applied when the vehicle is operated, it gives a great sense of deceleration to the occupant, which is not preferable. Therefore, in a normal automatic transmission, a one-way clutch is installed in parallel with a hydraulically operated friction element that acts as a reaction force element. In this case, by releasing the hydraulically actuated friction element as a reaction force element normally, the above deceleration feeling can be eliminated by free running of the one-way clutch.

When engine braking is required on a long downhill road or the like, an overrun clutch (a friction element for engine braking), which is a friction element as the reaction element in parallel with the one-way clutch, is hydraulically operated. Do not allow free running of the one-way clutch, so that the engine brake works.

By the way, when hydraulically operating a friction element for an engine brake, the conventional method is, for example, the actual open shovel 61-.
As disclosed in Japanese Patent No. 14124, an electric engine brake command is generated by a driver's manual operation of a switch, and hydraulic pressure is supplied to a friction element for engine braking by the engine brake command to realize hydraulic operation of the friction element. Was.

In addition, in hydraulically operating the friction element for engine braking, it is determined from the running conditions of the vehicle whether or not engine braking is required, and an engine braking command is generated when it is determined that engine braking is required. It has also been proposed to supply hydraulic pressure to a friction element for engine braking by this engine braking command and to engage the hydraulic element.

[0006]

By the way, when the engine is operated under high load with a large throttle opening of the engine, or when the engine brake is effective even during gear shifting, the operation may be hindered or a shock may occur. Therefore, even in the engine brake command state in which the engine brake command is issued, the engagement area of the engine brake friction element (overrun clutch) is determined as shown in FIG. 3, for example.

FIG. 3 shows the engagement area of the friction element (overrun clutch) for engine braking in the third speed range defined by the 3 → 2 downshift transmission line of the automatic transmission, and B is for engine braking. A friction element (overrun clutch) release area, and C is a hysteresis area as a dead zone set between them.

Now, let us consider the case where the accelerator pedal is released and the throttle opening TVO is set to 0 during traveling at the third speed.
When the vehicle speed VSP decreases to the engine brake request determination vehicle speed V ₁ , the release of the friction element (overrun clutch) for engine braking is commanded, and the vehicle speed VSP further decreases to 3 → 2 downshift transmission vehicle speed V _0. When this is done, a 3 → 2 downshift is commanded.

The release of the overrun clutch and the 3 → 2 downshift transmission during deceleration due to the release of the accelerator pedal will be described in detail with reference to FIG. If the vehicle speed VSP rapidly decreases from the point D equivalent value to the point E equivalent value after the accelerator pedal release instant t _{0, the} instant t at which the vehicle speed VSP decreases to the engine braking request determination vehicle speed V _{1.
At 1} , the command to release the overrun clutch is issued, and at the instant t ₂ when the vehicle speed VSP decreases to the 3 → 2 downshift transmission vehicle speed V ₀ , the 3 → 2 downshift transmission instruction is issued. In response to these commands, the overrun clutch, which is the friction element for the engine brake, completes the release from the instant t ₁ to the instant t ₄ after the hydraulic operation response delay Δt _EB , and renders the automatic transmission inoperable. The shifting friction element changes its state from the instant t ₂ to the instant t ₃ after the hydraulic operation response delay Δt _ST , and shifts the automatic transmission 3 → 2 downshift.

Therefore, after the accelerator pedal is released, the vehicle speed V
When the SP suddenly drops, it means that the release of the overrun clutch is not yet completed at the instant t ₃ when the automatic transmission performs the 3 → 2 downshift, and the overrun clutch is in the engaged state.

By the way, when the accelerator pedal is released before the power-on traveling, that is, the traveling state in which the positive torque is transmitted from the engine, the transmission torque may be reversed (zero cross) in the transmission torque during the gear shift. is there. Nevertheless, if the overrun clutch is not yet released during the above gear shift and is in the engaged state, so-called zero cross shock occurs with the reversal of the transmission torque, and the commercial value of the automatic transmission is reduced. Let

However, as shown in FIG.
Release instant of the pedal₀After that, the vehicle speed VSP is equivalent to point D
If it slowly decreases from the point F to the equivalent value,
Speed VSP is the engine braking request determination vehicle speed V₁Down to
Instant t_Five, The overrun clutch release command is issued.
And the overrun clutch is instant t_FiveHydraulically operated from
Response delay Δt_EBLater instant t₆Automatically release the
The speed VSP is set to 3 when the speed machine is in the engine braking disabled state.
→ 2 Downshift transmission vehicle speed V₀Instantaneous t
₇3 → 2 downshift gearshift command is issued to the corresponding gearshift
For friction element is instant t ₇To hydraulic operation response delay Δt_STAfter
Instant t₈State change to automatic transmission 3 down 2
Even if you shift gears, the automatic transmission shifts down 3 → 2
Instantaneous t when shifting₈Already released overrun clutch
Has been completed, causing the above zero-cross shock problem.
Absent.

From this point of view, it is conceivable to increase the engine brake request determination vehicle speed V ₁ so as to avoid the problem of zero cross shock during any sudden deceleration, and to solve the problem. In the vehicle speed range in which the overrun clutch is released due to the increase in the demand determination vehicle speed V ₁ , the required engine braking cannot be obtained and the driver is given a feeling of idling.

According to the present invention, since the problem of the zero cross shock occurs when the vehicle is rapidly decelerating, the engine brake request determination vehicle speed is increased at the time of the sudden deceleration, so that the problem of the zero cross shock can be obtained without the feeling of idling. The purpose is to eliminate.

[0015]

To this end, the engine brake control apparatus according to the first aspect of the present invention provides an engine brake control system when the vehicle speed falls below the engine brake request determination vehicle speed even in the engine brake command state. A downshift transmission vehicle speed lower than a vehicle speed lower than the engine brake request determination vehicle speed due to a further decrease in vehicle speed by issuing an engagement release command for the brake friction element to release the engine brake friction element from the hydraulically operated state. When a shift command is issued, a shift command is issued to cause a state change of the hydraulically actuated shift friction element, thereby performing the corresponding downshift shift, in the engine brake command state. Engine braking command detecting means for detecting the following, vehicle deceleration detecting means for detecting the deceleration of the vehicle, and these means In response to these signals, when the deceleration of the vehicle is equal to or higher than the set deceleration in the engine brake command state, the engine brake request determination vehicle speed is increased to increase the speed difference between the engine brake request determination vehicle speed and the downshift vehicle speed. And an engine braking request determination vehicle speed changing means for controlling the vehicle speed.

Even when the vehicle speed is lower than the engine brake request judgment vehicle speed, the automatic transmission releases the engine brake friction element by the engagement release command of the engine brake friction element when the vehicle speed falls below the engine brake request determination vehicle speed. It becomes impossible. Further, the automatic transmission changes the hydraulic operation state of the friction element for gear shifting according to the gear shift command when the vehicle speed becomes lower than the downshift gearshift vehicle speed lower than the engine brake request determination vehicle speed due to the further decrease in vehicle speed. Shift downshift.

By the way, the engine brake request determining vehicle speed changing means detects the deceleration detected value by the vehicle deceleration detecting means while the engine brake command detecting means detects that the engine brake command state is in effect. Is greater than or equal to the set deceleration, the engine brake request determination vehicle speed is increased to increase the speed difference between the engine brake request determination vehicle speed and the downshift vehicle speed.

Such an increase in the vehicle speed for determining the engine brake request speeds up the output of the engagement release command for the friction element for engine braking, and as a result, even if the vehicle deceleration is higher than the set value, the friction element It is possible to eliminate the above-mentioned situation in which the engagement release is delayed with respect to the state change of the shift friction element, that is, the downshift shift. Therefore, the problem of the zero cross shock can be eliminated even when the vehicle deceleration is larger than the set value.

When increasing the engine brake request determination vehicle speed, this is performed only under a large vehicle deceleration higher than the set value. Therefore, the engine brake request determination vehicle speed is increased under a small vehicle deceleration. In this case, the problem of the zero cross shock can be solved without causing the above-mentioned problem, that is, the problem that a necessary engine brake cannot be obtained and the driver feels idle.

Further, in the engine brake control device for an automatic transmission according to the second aspect of the present invention, the release of the engine braking friction element is set to the set deceleration in the engine brake request determination vehicle speed changing means. Is the limit value of the vehicle sudden deceleration that is delayed from the end of the downshift gearshift due to the change in the state of the gearshift friction element.

According to the configuration of the second aspect of the invention, a large vehicle deceleration equal to or higher than the above setting accurately corresponds to the sudden vehicle deceleration that causes the problem of the zero cross shock, and it is unnecessary to increase the engine braking request determination vehicle speed. It is possible to more reliably achieve the action and effect of the first aspect of the present invention.

Further, according to the engine brake control device for an automatic transmission according to the third aspect of the present invention, the engine brake request determination vehicle speed changing means has the following configuration. In other words, the engine brake request determination vehicle speed changing means is
The engine brake request determination vehicle speed is increased to such an extent that the end of releasing the friction element for engine braking is not delayed from the end of downshift due to a change in the state of the friction element for shifting. It is a thing.

According to the structure of the third aspect of the invention, the amount of increase in the engine brake request determination vehicle speed becomes the minimum necessary to realize the solution of the zero cross shock, and the engine brake request determination is made larger than necessary. Since the vehicle speed is not increased, the function and effect of the first invention can be achieved more reliably than the second invention.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of an engine brake control device of the present invention, in which 1 is an engine and 2 is an automatic transmission. The output of the engine 1 is adjusted by a throttle valve 4 which increases in opening from fully closed to fully open in conjunction with an accelerator pedal 3 operated by a driver, and an automatic transmission 2 has a control valve 5, more specifically a shift valve. The selected shift speed is determined by the combination of ON and OFF of the solenoids 6 and 7, and the engine power is shifted and output at a gear ratio corresponding to the shift speed.

The automatic transmission 2 is provided with a one-way clutch OWC as a reaction force receiving member in the transmission system to realize smooth upshift gear shifting and inertia running without feeling of deceleration. Further, the control valve 5 is provided with an engine brake solenoid 8 separately, and when the solenoid 8 is turned off by an electric signal, the automatic transmission 2 is arranged in parallel with the one-way clutch OWC and an overrun clutch OR as a friction element for engine brake is provided. It is assumed that the engine braking can be activated by fastening / C.

ON / OFF of the shift solenoids 6 and 7 and the engine brake solenoid 8 is controlled by a controller 9, and this controller includes a throttle valve 4
The signal from the throttle sensor 10 that detects the opening TVO of the vehicle, the signal from the vehicle speed sensor 12 that detects the vehicle speed VSP from the transmission output speed, and the signal from the vehicle body longitudinal acceleration sensor 12 that detects the vehicle body longitudinal acceleration g. Enter each. Here, the vehicle body longitudinal acceleration g has a negative value as the vehicle deceleration,
Therefore, the vehicle body longitudinal acceleration sensor 12 constitutes the vehicle deceleration detecting means in the present invention.

The controller 9 performs the following shift control and engine brake control based on these input information. First, the gear shift control will be described. The controller 9 executes a gear shift control program (not shown) to set the vehicle speed VSP.
Based on the throttle opening TVO and the gear shift line (not shown) having a gear shift line including the 3 → 2 downshift gear shift line of FIG. 3, a gear stage suitable for the current operating state (first gear to first gear). (4th speed). Then, the controller 9 selectively turns on the shift solenoids 6 and 7 so that the preferable shift speed calculated in this way is achieved. At this time, if the selected shift speed is different from the calculated preferable shift speed, the shift to the suitable shift speed is executed.

Next, to explain the engine brake control, the controller 9 performs this engine brake control based on the program shown in FIG. First, in step 21, an overdrive (fourth
It is determined whether or not it is in the third speed engine brake command state by whether or not the third speed engine brake range is in which the (speed) prohibition switch is turned on. Therefore, step 21 corresponds to the engine brake command detecting means in the present invention.

In the case of the third speed engine brake command state,
In step 22, the vehicle speed VSP is equal to
Vehicle brake request judgment Vehicle speed setting to increase vehicle speed
Value V _SIt is determined whether or not the above. Vehicle speed VSP is the vehicle speed set value
V_SIf so, in step 23, the sensor 12 detects the vehicle
The body longitudinal acceleration detection value g is read, and the step 24 is performed.
Then, this vehicle body longitudinal acceleration detection value g is set acceleration G₀Less than
Or not. Set acceleration G here₀Is shown in Figure 4.
As described above, the solution of overrun clutch OR / C
Vehicle reduction such that release is delayed compared to 3 → 2 downshift
Corresponds to the speed limit. Because of this step 24
Is the vehicle deceleration g is the set deceleration G₀Is it a sudden deceleration that is more than
It will be determined whether or not.

If the vehicle deceleration g is a rapid deceleration equal to or higher than the set deceleration G ₀ , the engine brake request determination vehicle speed V ₁ in FIG. 3 is set in step 25 corresponding to the engine brake request determination vehicle speed changing means in the present invention. Increase by a predetermined amount ΔV ₁ (g). Here, the engine brake request determination vehicle speed increase amount ΔV ₁ (g) is set so that the release of the overrun clutch OR / C does not delay after the 3 → 2 downshift, and this delay corresponds to the vehicle deceleration g. Since it increases with an increase, it is determined as a function of the vehicle deceleration g.

[0031] In the next step 26, based on the engine brake request determination vehicle speeds V ₁ to the raised as described above, when the vehicle speed VSP is lowered to the determination vehicle speeds V ₁ to, emit overrunning clutch engagement release instruction engine The brake solenoid 8 is switched from OFF to ON and the overrun clutch OR / C is released from the hydraulically operated state to execute the overrun clutch engagement / release control during deceleration.

By the way, the above-mentioned increase in the engine brake request determination vehicle speed V ₁ accelerates the output of the engagement release command of the overrun clutch OR / C, and as a result,
Even under rapid deceleration where the vehicle deceleration g exceeds the set deceleration G ₀ , the engagement release of the overrun clutch OR / C is 3 →
It is possible to prevent the zero cross shock caused by this from occurring without delaying from the 2 downshift.

Then, the engine braking request determination vehicle speed V
This is the overrun clutch OR when ₁ rises.
/ C is released only under a large vehicle deceleration equal to or higher than the set deceleration G ₀ that delays the 3 → 2 downshift shift, and the increase amount ΔV ₁ (g ) Is set to such an extent that the delay is eliminated, so that the engine braking request determination vehicle speed V ₁ is increased only when and when it is necessary.
The zero crossing is performed without the above-mentioned problem that occurs when the engine braking request determination vehicle speed V ₁ is increased more than necessary and when the vehicle speed V ₁ is increased more than the required amount, that is, without giving a bad running feeling to the driver. It is possible to solve the shock problem.

Then, in step 22, the vehicle speed VSP becomes
If it is determined that the vehicle speed setting value V _S for increasing the engine brake request determination vehicle speed is not greater than or equal to the vehicle deceleration g, or if it is determined in step 24 that the vehicle deceleration g is not the rapid deceleration equal to or greater than the set deceleration G ₀ , step 27 Then, V ₁ in FIG. 3 is set as it is to the engine brake request determination vehicle speed, and in the next step 28, the vehicle speed VSP is determined based on the engine brake request determination vehicle speed V _{1 which} has not been changed. _When it drops to _1, the engine brake solenoid 8 is issued by issuing an overrun clutch engagement release command.
Switch from OFF to ON, and overrun clutch O
The overrun clutch engagement / disengagement control during deceleration such as releasing the R / C from the hydraulically operated state is executed.

If it is determined in step 21 that the engine speed is not in the third speed engine brake range, step 2
In 9, overrun clutch O required in other ranges
Performs engine brake control through the engagement / release of R / C. Also in the engine brake control in other ranges, the same action and effect as in the case of the above-described third speed engine brake range can be achieved by the same processing as in steps 22 to 27 as required.

In the above embodiment, the vehicle deceleration g is directly detected by the vehicle body longitudinal acceleration sensor 12, but the invention is not limited to this.
It is needless to say that the vehicle deceleration g may be calculated by calculating the time change ratio of the vehicle speed VSP detected in 1. or the vehicle deceleration g may be calculated from the braking pressure detected.

[Brief description of drawings]

FIG. 1 is a system diagram showing an engine brake control device according to an embodiment of the present invention.

FIG. 2 is a flow chart showing an engine brake request determination vehicle speed change control program and an overrun clutch release control program that should be executed by the controller in the embodiment.

FIG. 3 is a region diagram showing an overrun clutch engagement region together with a 3 → 2 downshift transmission line of an automatic transmission.

FIG. 4 is a time chart showing a difference in overrun clutch release timing when the vehicle is rapidly decelerated and when the vehicle is slowly decelerated.

[Explanation of symbols]

1 engine 2 automatic transmission 3 accelerator pedal 4 Throttle valve 5 control valves 6 shift solenoid 7 shift solenoid 8 engine brake solenoid 9 Controller 10 Throttle sensor 11 Vehicle speed sensor 12 Vehicle body longitudinal acceleration sensor (vehicle deceleration detection means)

Continuation of the front page (56) Reference JP-A-2-17258 (JP, A) JP-A-1-229145 (JP, A) JP-A-61-55450 (JP, A) JP-A-2-17254 (JP , A) JP-A-1-269748 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40 -63/18

Claims (3)

(57) [Claims] 1. Even in the engine brake command state, when the vehicle speed falls below the engine brake request determination vehicle speed, a disengagement command for the engine brake friction element is issued to release the engine brake friction element from the hydraulically operated state. The engine braking request is made due to a further decrease in vehicle speed.
When the vehicle speed is lower than the downshift gearshift speed lower than the judgment vehicle speed , a gearshift command is issued to cause a state change of the hydraulically actuated friction element for gearshifting, thereby performing the corresponding downshift gearshift. In the automatic transmission, the engine brake command detecting means for detecting the engine brake command state, the vehicle deceleration detecting means for detecting the deceleration of the vehicle, and the engine brake command in response to the signals from these means. When the deceleration of the vehicle is above the set deceleration in the state,
Engine is raised the engine braking request determination vehicle speed
Speed difference between the vehicle speed for determining the braking request and the vehicle speed for downshifting
An engine brake control device for an automatic transmission, comprising: an engine brake request determination vehicle speed changing means for increasing the vehicle speed. 2. The engine brake request determination vehicle speed changing means according to claim 1, wherein the set deceleration is determined by the end of release of the engine brake friction element from the end of downshift gear shift due to a change in state of the gear shift friction element. An engine brake control device for an automatic transmission, which has a limit value of a vehicle sudden deceleration that is delayed. 3. The engine brake request determination vehicle speed changing means according to claim 2, wherein the end of releasing the friction element for engine braking is not later than the end of downshift gear shifting due to a change in the state of the friction element for shifting. An engine brake control device for an automatic transmission, wherein the engine brake request determination vehicle speed is increased to a certain degree.