CA1277513C - Hydraulic control for vehicle transmissions to be shifted automatically - Google Patents
Hydraulic control for vehicle transmissions to be shifted automaticallyInfo
- Publication number
- CA1277513C CA1277513C CA000508312A CA508312A CA1277513C CA 1277513 C CA1277513 C CA 1277513C CA 000508312 A CA000508312 A CA 000508312A CA 508312 A CA508312 A CA 508312A CA 1277513 C CA1277513 C CA 1277513C
- Authority
- CA
- Canada
- Prior art keywords
- pressure
- fed
- valve
- hydraulic control
- piston
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Control Of Transmission Device (AREA)
Abstract
A B S T R A C T
A hydraulic control for automatic vehicle tranmissions whereby shifting valves actuate the clutches/brakes by means of an operating pressure. The shifting points of the downshift valves and the operating pressure, being governed by engine load (accelerator pedal setting) and speed, and being fed, as control pressure (throttle and regulator pressures), to the downshift valves. In the case of supercharged engines, for the purpose of influencing the quality of the shifting, the intake pressure is also fed to at least one shifting valve, as a control pressure either directly or through a pressure converter pressure. The intake pressure is passed to the spring chamber in the shifting valve, thus supporting the pressure of the spring upon the piston, and the contact pressure of the clutch or brake to be released is increased.
A hydraulic control for automatic vehicle tranmissions whereby shifting valves actuate the clutches/brakes by means of an operating pressure. The shifting points of the downshift valves and the operating pressure, being governed by engine load (accelerator pedal setting) and speed, and being fed, as control pressure (throttle and regulator pressures), to the downshift valves. In the case of supercharged engines, for the purpose of influencing the quality of the shifting, the intake pressure is also fed to at least one shifting valve, as a control pressure either directly or through a pressure converter pressure. The intake pressure is passed to the spring chamber in the shifting valve, thus supporting the pressure of the spring upon the piston, and the contact pressure of the clutch or brake to be released is increased.
Description
The invention relates to a hydraulic control for automatic vehic]e transmissions and more specifically, to such transmissions having shifting valves which actuate the clutches/brakes by means of an operating pressure. A
comparable hydraulic control in which the shifting points are determined as a function of engine load and speed, is described in ADZ, year 77, volume 9/1975, on pages 246 to 249. The main pressure valve is followed by a throttle pressure valve which produces a pressure dependent upon engine load independently of the selector lever position. A cam, which is rotated by an accelerator control cable according to the accelerator pedal setting, displaces the valve piston so that the spring is preloaded according to the required engine load whexeby the load dependent pressure, the throttle pressure, is produced. Arranged in parallel with the throttle pressure valve is a modulating valve, to which operating pressure and throttle pressure are also fed in the same way. In accordance with the valve and piston area ratio, the modulating pressure is usually higher than the throttle pressure and varies the operating pressure, as a function of engine load, in order to influence the shift pressure systems which determines the pressure in the servo piston during the shifting process.
The pressure dependent upon the driving speed of the vehicle is produced by the regulator arranged upon the output shaft and, in shift position 1, ~ or 3, for example, non return valves are provided to prevent shifting down to lower gears above a predetermined speed. Shifting up to gears above the selected position is also prevented.
Hydraulic controls of this and similar types have been found satisEactory for vehicles equipped with naturally 1'~77~;13 aspirated engines in conjunction with automatic transmissions because, by means of the throttle pressure valve and regulator, dependence upon engine load and driving speed is achieved with sufficient accuracy to determine the shifting points and to engage and disengage the shift elements, and is transferred to the shifting pressure system as throttle and regulator pressure. Necessary overlapping shifts, when one clutch or brake is released and a second is engaged, are effected with the aid of the above mentioned pressures by means of shifting and time control valves in such a manner as to avoid any appreciable gear shifting jolt which is unpleasant for the driver and occupants of a vehicle.
In the case of vehicles equipped with supercharged engines, however, a control of this kind is unsatisfactory since engine torque cannot be determined accurately from accelerator pedal setting.
It is therefore the purpose of the invention to develop still further a hydraulic control so that it may also be used for super charged engines in this way, which has been found satisfactory in principle. At the same time, structural and equipment expense is to be kept to a minimum.
This purpose is accomplished as set forth in the characterizing portion of claim 1.
Feeding intake pressure to at least one shifting valve makes it possible to influence the operation, at least of this shifting valve, as a function of intake pressure.
In order to maintain adequate pressure in a clutch or brake to be released for a downshift, use is made of the 4/3 downshift valve for example. The piston or pistons of this downshift valve, which operates as a modulating valve, is influenced 1~2775~3 by driving speed dependent regulator pressure and/or by a spring adapted to this operating pressure. The level of the operating pressure during the shift is also influenced by the intake pressure, since engine torque may vary before and during the shift as a function of engine r.p.m. and throttle valve opening, accelerator pedal setting.
If the intake pressure is fed dire~tly, i.e., without conversion, to the pressure valve spring chamber, the`design is particularly simple since no pressure boxes are required for converting the pressure. Any sealing problems arising may be solved quite simply by the provision of relatively long sealing surfaces and sleeves.
In the drawing attached hereto:
Figures 1 and lA are schematic diagrams showing the control mechanism of the present invention;
Figure 2 is a graph showing pressure against time of an overlapping shift;
Figure 3 is a schematic view of simplified control for an overlapping shift;
Figure 4 is a cross-sectional view of a 4/3 down shifting valvei and Figure 5 is a cross-sectional view of another embodiment of a 4/3 shi~ting valve.
In the diagram according to Figure 1, shift valve 2 is in setting D corresponding to an unrestricted automatic driving mode. Pressure is built up by a pump 3 which draws oil from gearbox sump 31 and delivers it to master valve which operates as a modulating valve. The pressure is dependent upon spring 320 and a shift throttle pressure line 341, and is produced in throttle valve 34 and modulating valve 33 as a function of accelerator pedal setting. In ~;~775~3 gears 1 to 3, this pressure is fed to downshift valve (4/3) through line 11, so that the piston or pistons 12 are moved to the right hand terminal position against the pressure spring 13. This locks downshift valve (4/3) in these gear positions. In the 4th gear, the main pressure is fed only through line 14 to downshift valve (4/3) 1. A speed dependent pressure is produced in regulator 35 and may also be fed to downshift valve (4/3) 1 by line 35'. C' represents the brake which releases in a shift from 4th to 3rd gear and A is the clutch which is activated for this shift. srake CI is also associated with the clutch valve plus damper C'l and clutch A of damper A 1.
Figure 2 shows an overlapping shift, e.g., a pull downshift from 4th to 3rd gear. In this case, PC' is the pressure pattern in brake C' which is to be released, while PA is the pressure pattern in clutch A to be engaged.
5 represents the pull-up release time delay of br~ke C' and clutch A, while curve nMOt indicates engine r.p.m.
during the shift. Curve PL represents intake pressure.
The overlapping shift from 4th to 3rd gear operates as follows when the vehicle is pulling a load:
When the accelerator pedal is fully depressed, i.e., in "kick down", and at a predetermined r.p.m. in the drive train, the downshift from 4th to 3rd gear is initiated.
The pressure in brake C' drops, as shown in diagrammatical curve PC', while over the same period of time, the pressure in clutch A, to be engaged, is built up as shown in curve PA.
During pull-up release time delays 5, the pattern of curve PC', unaffected by intake pressure, is according to 52 and, with boost pressure, it is according to 51. In this connection, curve 51, shown horizontal, may assume any shape according to 1'~77513 the actual intake pressure, but in this example, it is shown as a straight line for the sake of simplicity. As far as point 53 therefore, engine torque is transferred only through brake C'. From point 54, it is transferred through clutch A. Between these two points, during pull-up release time delay 5, torque transfer takes place in brake C'. The intake pressure in modulating the 4/2 downshift valve for the main pressure of brake C' to be disengaged, produces a more realistic adaptation of contact pressure to the torques to be transferred which, in the case of supercharged engines, is not provided merely by modulation according to accelerator pedal setting and spring 13 arranged in downshift valve 1.
Figure 3 shows diagrammatically a carburetor 6, a pressure box 7 and downshift valve (4/3) 10. In this case, the intake pressure, at line 61, may be fed to the downshift valve 10 either directly or through a pressure box 7 as hydraulic pressure in line 71.
With direct feed in the form cf a gas, a sealing element 16 is arranged in spring chamber 15 (Fig. 4), in such a manner that a relatively large sealing surface 164 seals spring chamber 15, which is acted upon by intake pressure, from hydraulically acted upon piston chambers 18 of downshift valve 10, by the sealing sleeve 16 against inner end 162 of which spring 13 bears. Outer end 163 of sealing sleeve 16 bears against piston 12.
A second sealing arrangement may be seen in Figure 5.
Mounted in a groove 122 on shaft 121 of a piston 120-is the bead 201 of a thin walled sleeve 200, secured by a retaining element 210. The sleeve 200 is secured to valve housing 101 by means of a clamp 220 and spring chamber 150 is therefore reliably sealed off from piston chambers 180. Retaining , - .
1.~775~3 element 210 is also acted upon by spring 130 and carries out the longitudinal movements of the piston in conjunction with the pressure modulation. In contrast to this, clamp 220 is secured in the valve housing.
Since the absolute seal provided by the sleeve makes it possible to design contact surfaces between the clamp body 220 and the retaining element to be easy running in view of gap 214/222-, the modulation movement of piston 120 will not be impeded by friction.
comparable hydraulic control in which the shifting points are determined as a function of engine load and speed, is described in ADZ, year 77, volume 9/1975, on pages 246 to 249. The main pressure valve is followed by a throttle pressure valve which produces a pressure dependent upon engine load independently of the selector lever position. A cam, which is rotated by an accelerator control cable according to the accelerator pedal setting, displaces the valve piston so that the spring is preloaded according to the required engine load whexeby the load dependent pressure, the throttle pressure, is produced. Arranged in parallel with the throttle pressure valve is a modulating valve, to which operating pressure and throttle pressure are also fed in the same way. In accordance with the valve and piston area ratio, the modulating pressure is usually higher than the throttle pressure and varies the operating pressure, as a function of engine load, in order to influence the shift pressure systems which determines the pressure in the servo piston during the shifting process.
The pressure dependent upon the driving speed of the vehicle is produced by the regulator arranged upon the output shaft and, in shift position 1, ~ or 3, for example, non return valves are provided to prevent shifting down to lower gears above a predetermined speed. Shifting up to gears above the selected position is also prevented.
Hydraulic controls of this and similar types have been found satisEactory for vehicles equipped with naturally 1'~77~;13 aspirated engines in conjunction with automatic transmissions because, by means of the throttle pressure valve and regulator, dependence upon engine load and driving speed is achieved with sufficient accuracy to determine the shifting points and to engage and disengage the shift elements, and is transferred to the shifting pressure system as throttle and regulator pressure. Necessary overlapping shifts, when one clutch or brake is released and a second is engaged, are effected with the aid of the above mentioned pressures by means of shifting and time control valves in such a manner as to avoid any appreciable gear shifting jolt which is unpleasant for the driver and occupants of a vehicle.
In the case of vehicles equipped with supercharged engines, however, a control of this kind is unsatisfactory since engine torque cannot be determined accurately from accelerator pedal setting.
It is therefore the purpose of the invention to develop still further a hydraulic control so that it may also be used for super charged engines in this way, which has been found satisfactory in principle. At the same time, structural and equipment expense is to be kept to a minimum.
This purpose is accomplished as set forth in the characterizing portion of claim 1.
Feeding intake pressure to at least one shifting valve makes it possible to influence the operation, at least of this shifting valve, as a function of intake pressure.
In order to maintain adequate pressure in a clutch or brake to be released for a downshift, use is made of the 4/3 downshift valve for example. The piston or pistons of this downshift valve, which operates as a modulating valve, is influenced 1~2775~3 by driving speed dependent regulator pressure and/or by a spring adapted to this operating pressure. The level of the operating pressure during the shift is also influenced by the intake pressure, since engine torque may vary before and during the shift as a function of engine r.p.m. and throttle valve opening, accelerator pedal setting.
If the intake pressure is fed dire~tly, i.e., without conversion, to the pressure valve spring chamber, the`design is particularly simple since no pressure boxes are required for converting the pressure. Any sealing problems arising may be solved quite simply by the provision of relatively long sealing surfaces and sleeves.
In the drawing attached hereto:
Figures 1 and lA are schematic diagrams showing the control mechanism of the present invention;
Figure 2 is a graph showing pressure against time of an overlapping shift;
Figure 3 is a schematic view of simplified control for an overlapping shift;
Figure 4 is a cross-sectional view of a 4/3 down shifting valvei and Figure 5 is a cross-sectional view of another embodiment of a 4/3 shi~ting valve.
In the diagram according to Figure 1, shift valve 2 is in setting D corresponding to an unrestricted automatic driving mode. Pressure is built up by a pump 3 which draws oil from gearbox sump 31 and delivers it to master valve which operates as a modulating valve. The pressure is dependent upon spring 320 and a shift throttle pressure line 341, and is produced in throttle valve 34 and modulating valve 33 as a function of accelerator pedal setting. In ~;~775~3 gears 1 to 3, this pressure is fed to downshift valve (4/3) through line 11, so that the piston or pistons 12 are moved to the right hand terminal position against the pressure spring 13. This locks downshift valve (4/3) in these gear positions. In the 4th gear, the main pressure is fed only through line 14 to downshift valve (4/3) 1. A speed dependent pressure is produced in regulator 35 and may also be fed to downshift valve (4/3) 1 by line 35'. C' represents the brake which releases in a shift from 4th to 3rd gear and A is the clutch which is activated for this shift. srake CI is also associated with the clutch valve plus damper C'l and clutch A of damper A 1.
Figure 2 shows an overlapping shift, e.g., a pull downshift from 4th to 3rd gear. In this case, PC' is the pressure pattern in brake C' which is to be released, while PA is the pressure pattern in clutch A to be engaged.
5 represents the pull-up release time delay of br~ke C' and clutch A, while curve nMOt indicates engine r.p.m.
during the shift. Curve PL represents intake pressure.
The overlapping shift from 4th to 3rd gear operates as follows when the vehicle is pulling a load:
When the accelerator pedal is fully depressed, i.e., in "kick down", and at a predetermined r.p.m. in the drive train, the downshift from 4th to 3rd gear is initiated.
The pressure in brake C' drops, as shown in diagrammatical curve PC', while over the same period of time, the pressure in clutch A, to be engaged, is built up as shown in curve PA.
During pull-up release time delays 5, the pattern of curve PC', unaffected by intake pressure, is according to 52 and, with boost pressure, it is according to 51. In this connection, curve 51, shown horizontal, may assume any shape according to 1'~77513 the actual intake pressure, but in this example, it is shown as a straight line for the sake of simplicity. As far as point 53 therefore, engine torque is transferred only through brake C'. From point 54, it is transferred through clutch A. Between these two points, during pull-up release time delay 5, torque transfer takes place in brake C'. The intake pressure in modulating the 4/2 downshift valve for the main pressure of brake C' to be disengaged, produces a more realistic adaptation of contact pressure to the torques to be transferred which, in the case of supercharged engines, is not provided merely by modulation according to accelerator pedal setting and spring 13 arranged in downshift valve 1.
Figure 3 shows diagrammatically a carburetor 6, a pressure box 7 and downshift valve (4/3) 10. In this case, the intake pressure, at line 61, may be fed to the downshift valve 10 either directly or through a pressure box 7 as hydraulic pressure in line 71.
With direct feed in the form cf a gas, a sealing element 16 is arranged in spring chamber 15 (Fig. 4), in such a manner that a relatively large sealing surface 164 seals spring chamber 15, which is acted upon by intake pressure, from hydraulically acted upon piston chambers 18 of downshift valve 10, by the sealing sleeve 16 against inner end 162 of which spring 13 bears. Outer end 163 of sealing sleeve 16 bears against piston 12.
A second sealing arrangement may be seen in Figure 5.
Mounted in a groove 122 on shaft 121 of a piston 120-is the bead 201 of a thin walled sleeve 200, secured by a retaining element 210. The sleeve 200 is secured to valve housing 101 by means of a clamp 220 and spring chamber 150 is therefore reliably sealed off from piston chambers 180. Retaining , - .
1.~775~3 element 210 is also acted upon by spring 130 and carries out the longitudinal movements of the piston in conjunction with the pressure modulation. In contrast to this, clamp 220 is secured in the valve housing.
Since the absolute seal provided by the sleeve makes it possible to design contact surfaces between the clamp body 220 and the retaining element to be easy running in view of gap 214/222-, the modulation movement of piston 120 will not be impeded by friction.
Claims (6)
1. A hydraulic control for automatically operating change-speed gear in motor vehicles, with pilot valves for the operation of shifting couplings/brakes (A,C') with a working pressure, in which the switch points of the pilot valves and the working pressure are set in dependence of the engine load (accelerator position) and of velocity and are fed to the pilot valves as control pressures (throttle and regulator pressures), characterized in that in vehicles with supercharged engines a boost pressure (PL, line 61,71) is fed to at least one reversing pilot valve (1, 10, 100) for influencing shift quality.
2. A hydraulic control according to Claim 1, charac-terized in that the boost pressure (PL, line 61) is fed directly to at least one reversing pilot valve (1, 10, 100).
3. A hydraulic control according to Claim 1, charac-terized in that the boost pressure (PL, line 61) is trans-formed by a pressure converter (pressure element 7) into a hydraulic pressure (line 71) and is fed to at least one reversing pilot valve (1, 10, 100).
4. A hydraulic control according to Claim 2, charac-terized in that the boost pressure (PL) is fed to a spring chamber (15, 150) of the 4/3 reversing pilot valve (1, 10, 100) and promotes the action of a spring, so that a contact pressure (PC') of the coupling/brake (C') to be released is held in dependence of the boost pressure (PL) at a higher level (curve 51) during the shift (clutch delay 5).
5. A hydraulic control according to Claim 4, charac-terized in that in the spring chamber (15) of the 4/3 reversing pilot valve (10) a sealing element (16) having the form of a hollow piston is arranged, a hollow space (161) of which accommodates a spring (13) which presses on the bottom (162), while the outer bottom (163) bears on a piston (12) and the outer cylinder surface (164) seals off the spring chamber (15) from a piston chamber (18) to which boost pressure (PL) is fed through the line (61), and wherein the sealing element (16) is given a relatively long dimension to improve sealing.
6. A hydraulic control according to Claim 4, charac-terized in that on a shaft (121) of the piston (120) in a groove (122) a bead (201) of a sleeve (200) is mounted and is clamped by the bore (211) of a receiving body (210), while the other end of the thin-walled sleeve (200) is tensioned by means of a clamp element (220) in a bore extension (102) in the valve body (101) and seals off the spring chamber (150) from a piston chamber (180), urging a compression spring (130) with one side against a shoulder (212) of the receiving body (210) and bears with the other end against the valve housing (valve body 101), wherein the guiding surfaces (cylinder 213, bore 221) are constructed short and with a gap (214/222) for particular ease of movement of piston 120 and wherein boost pressure is fed directly to the spring chamber (150).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| LU85/00201 | 1985-05-04 | ||
| LU8500201 | 1985-05-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1277513C true CA1277513C (en) | 1990-12-11 |
Family
ID=19734210
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000508312A Expired - Lifetime CA1277513C (en) | 1985-05-04 | 1986-05-02 | Hydraulic control for vehicle transmissions to be shifted automatically |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1277513C (en) |
| ES (1) | ES8702840A1 (en) |
-
1986
- 1986-04-29 ES ES554510A patent/ES8702840A1/en not_active Expired
- 1986-05-02 CA CA000508312A patent/CA1277513C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| ES8702840A1 (en) | 1987-01-16 |
| ES554510A0 (en) | 1987-01-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |