DE69031519T2 - Hydraulic control system for floor closer - Google Patents

Description

The invention relates to a hydraulic control system for a floor door closer which is applicable to a right-hand swing door, a left-hand swing door or a two-part door.

A conventional floor door closer of the above-mentioned type comprises a device for achieving a delayed actuation function by means of which the door can be closed slowly from a fully opened state to a certain opening angle state, a device for closing the door at a normal closing speed, ie a first closing speed, from the certain opening angle state of the door to an opening angle close to a position in which the door is fully closed, and a device for closing the door at a second closing speed which is lower than the first closing speed. Another conventional floor door closer is further provided with a device equipped to perform a snap action for closing the door immediately before it is closed by an angle of about 20 to 30 to close it completely. Another conventional floor door closer is provided with a device for achieving a back-check function to prevent the rapid opening of the door at an opening angle between a predetermined opening angle and the full opening angle, so as to prevent the door, a doorknob or a wall to which the door is attached from being damaged by, for example, an inadvertent rapid opening of the door by an external force.

In order to achieve the check function, a mechanical device for increasing the door opening force and restricting the rapid opening of the door and a hydraulic piping arrangement for restricting the rapid opening of the door by applying a damping function of the hydraulic pressure are provided. The hydraulic piping arrangement may or may not include a mechanism for precisely adjusting the hydraulic pressure that provides the damping function, as described, for example, in Japanese Utility Model Publication No. 52-15639.

With the well-known floor door closer of the type that contains a mechanical check mechanism, it is difficult to precisely adjust the check function.

On the other hand, with a conventional floor door closer using a hydraulic line arrangement, it might be possible to control the first and second door closing speeds, the back-check function, the delayed operation and latching action. However, some floor door closers of this type do not contain a mechanism for precisely adjusting these functions or operations, or some other floor door closers of this type, although containing mechanisms for precisely adjusting these functions or operations, have a complicated structure for achieving these functions or operations or require laborious adjustment work which is time-consuming and expensive and is therefore impractical.

Attention is drawn to US-A-3605339 which describes a hydraulic control system according to the preamble of claim 1 and in which the valve 122 in the channel 118 acts not only as a check valve when the door is opened but also as a door speed control valve when the door is closed. It is therefore difficult to adjust it so precisely that the two functions (check and door closing speed control) are carried out in an appropriate or desired manner.

Reference should also be made to US-A-3042957, in which the oil control system is applied to a door which can be opened in both directions and in which the latching action is mainly described, in which three oil passages 102, 124, 118 are formed independently. However, the middle short passage 124 for the latching action is formed independently.

The invention is based on the object of essentially overcoming the deficiencies or disadvantages associated with the above-described prior art and of providing a hydraulic control system for a floor door closer with a hydraulic line arrangement for easily and accurately achieving various functions, such as setting functions for the first and second door speed, and a check function in suitable combination with these, in order to thereby achieve the ideal door opening and closing operation.

These and other objects can be achieved according to the invention by a hydraulic control system for a door closer comprising a door closer housing in which a cylinder portion is formed in which a piston is linearly moved by a door opening operation against the biasing force of a return spring, the cylinder portion being divided into a front piston chamber and a rear piston chamber by the arrangement of the piston and the door is then automatically closed by the stored return force of the spring, the system comprising a check valve device for restricting the flow of the hydraulic oil when the door is opened and closed, a check adjustment valve device for adjusting the speed of the piston in a door opening angle range between a predetermined door opening angle position and a fully opened door angle position, and a speed adjustment valve device for adjusting the speed of the piston in a door closing angle range between a door closing angle position and an approximately closed door angle position, characterized in that the door closer is a floor door closer and the system further comprises a snap-in operation device for increasing the speed of the Piston from the nearly closed door angle position to a fully closed door angle position and that first and second oil passages extending longitudinally on a side wall of the cylinder portion are independently formed so as to communicate with the rear and front piston chambers, the first oil passage having a front passage formed in a front portion therein, a rear passage formed in a rear portion therein, and front and rear intermediate passages formed between the front and rear passages, a first check valve of the check valve device allowing hydraulic oil flow only from the front chamber to the rear chamber is provided between the two intermediate passages in the first oil passage and the check adjustment valve device is provided in the front passage of the first oil passage, the snap-in device being effective when the rear passage communicates with the rear intermediate passage of the first oil passage, the second oil passage having a front passage formed in a front portion therein, a rear passage formed in a rear portion therein, and a rear intermediate passage formed near the rear passage, a second check valve allowing hydraulic oil flow only from the rear chamber into the front chamber is provided in the front passage of the second oil passage, and the speed adjusting valve device has two speed adjusting valves, one of which is a first speed adjusting valve arranged in the rear intermediate passage near the rear passage of the second oil passage so as to adjust the speed of the piston from a fully opened door position to a predetermined door closing angle position, and the other of which is a second speed adjusting valve disposed in the rear passage of the second oil passage so as to adjust the speed of the piston from a predetermined door closing angle position to an approximately closed door angle position.

In a preferred embodiment of the invention, the snap-in adjustment valve is arranged in the rear intermediate channel.

The deceleration action adjusting valve may be arranged in the second oil passage to adjust the amount of displacement of the hydraulic oil moved from the rear piston chamber in the door closing area to the front piston chamber at the time when the piston moves from the fully opened door angle position to the first door closing angle position.

The snap action adjusting valve and the deceleration action adjusting valve may be integrated together in the hydraulic piping arrangement in addition to the check adjusting valve and the first and second speed adjusting valves.

In the hydraulic control system for a floor door closer having the above features, the piston is moved linearly to the rear piston chamber due to a door opening operation, whereby the return spring is compressed and the door is opened to a position of a predetermined opening angle.

In the event that the door is moved from the fully closed position (0º) to a position of predetermined opening angle (for example, 70º), the hydraulic oil accumulated in the front piston chamber flows freely through the first oil passage and the check valve into the rear piston chamber. At this moment, the check valve in the second oil passage is closed by the hydraulic oil, so that the hydraulic oil cannot enter the second oil passage.

Then, in the case that the door is opened from the position of a predetermined opening angle (for example, 70º) to the fully opened position, the hydraulic oil in the front piston chamber flows into the rear piston chamber through the check adjusting valve in the first oil passage and the check valve. At this moment, the amount of displacement of the hydraulic oil can be precisely adjusted by means of the check valve arranged in the first oil passage, whereby an unintentional rapid door opening which may be caused by strong wind or an external force can be avoided.

In the case that the door is closed from the fully opened door angle position to a certain door closing angle position (for example, 70º), the hydraulic oil in the rear piston chamber flows into the front piston chamber through the second oil passage while the check valve is opened. At this moment, the amount of the hydraulic oil displaced is adjusted by means of the first and second speed adjusting valves arranged in the second oil passage. In the case that the deceleration action adjusting valve is further arranged in the second oil passage, the hydraulic oil in the rear piston chamber flows through the first and second second speed adjusting valve and the deceleration action adjusting valve into the front piston chamber while the check valve is opened. At this moment, the amount of the hydraulic oil displaced can be precisely adjusted by means of the first and second speed adjusting valves and the deceleration action adjusting valve arranged in the second oil passage. The hydraulic oil in the front piston chamber flows into the middle portion of the first oil passage while the check valve in the first oil passage is closed by the hydraulic oil, so that the hydraulic oil cannot flow into the front piston chamber through the first oil passage.

In the case where the door is closed from the predetermined closing angle position (for example, 70°) in a first door closing speed range to an opening angle near a position where the door is completely closed, the hydraulic oil in the rear piston chamber flows into the front piston chamber through the first and second speed adjusting valves at a time when the oil passage in which the first speed adjusting valve of the second oil passage is arranged is closed at the piston sealing surface. At this moment, the amount of hydraulic oil displaced is accurately adjusted by means of the speed adjusting valve arranged in one of the opened oil passages in two branched oil passages of the second oil passage in which the first and second speed adjusting valves are arranged. In a usual operation, the first speed is preset to be faster than the second speed, and the amount of hydraulic oil displaced can be adjusted by means of the first speed adjusting valve. can be precisely adjusted in the first speed range.

When the door is closed in the second speed range, the hydraulic oil in the rear piston chamber flows into the front piston chamber through the second oil passage and the second speed adjusting valve. At this moment, the amount of the displaced hydraulic oil can be precisely adjusted by means of the second speed adjusting valve.

In addition, in the case that the latching action adjusting valve is arranged in the first oil passage, the hydraulic oil in the rear piston chamber flows into the front piston chamber through the first oil passage and the latching action adjusting valve by opening a portion of the oil passage in which the latching action adjusting valve is arranged on the piston sealing surface. Accordingly, the door closing speed is increased just before the door is closed so as to reliably close the door.

For a better understanding of the invention and to show actual embodiments, reference is now made to the accompanying drawings in the form of preferred embodiments. They show:

Fig. 1 is a longitudinal section of a floor door closer, which does not show the invention, but is helpful for understanding the invention,

Fig. 2 is an elevation of the floor door closer according to Fig. 1,

Fig. 3, 4, 5, 6, 7 and 8 show the sectional views III-III, IV-IV, V-V, VI-VI, VII-VII and VIII-VIII, respectively shown in Fig. 1,

Fig. 9 is a longitudinal section showing part of a first embodiment of a floor door closer according to the invention,

Fig. 10 and 11 the sectional views X-X and XI-XI in Fig. 1,

Fig. 12 is a longitudinal section showing part of a second embodiment,

Fig. 13 and 14 the sectional views XIII-XIII and XIIII-XIIII in Fig. 12,

Fig. 15 is a cross-section of part of a third embodiment,

Fig. 16 and 17 the sectional views XVI-XVI and XVII-XVII respectively in Fig. 15 and

Fig. 18 is a view showing the relationship between the door opening angles and the respective functions of the hydraulic adjustment system of the floor door closer in the door opening and closing range.

Figures 1 to 8 show a floor door closer equipped with a first and a second speed mechanism for controlling the door closing speed and a return mechanism for slowly opening a door.

Figures 1 and 2 show a longitudinal section and an elevational view, respectively, of the entire structure of a floor door closer, the floor door closer having a door closer housing 8 such as a door closer body with a cylinder section 9, which is formed at the right end of the illustration.

The cylinder section 9 of the door closer housing 8 has an open end which is closed by a plug 12 and another end which is closed in a liquid-tight manner but has an opening 8a in the upper region of the closed end which is closed in a liquid-tight manner by a cover 29. In this structure, the interior of the cylinder section 9 is divided into a front piston chamber A which is arranged on the left side of a piston 7 and a rear piston chamber B which is arranged on the right side of the piston 7.

In the front piston chamber A, a main shaft 1 is rotatably supported by a bottom of the door closer housing 8 and the cover 29 via bearings 31 and 31 with one end of the shaft 1 extending outward. A cam 32 of approximately heart shape is supported on the main shaft 1. In addition, in the front piston chamber A, a pair of sliding plates 3 and 3 are arranged, which form a vertical sandwich structure with the cam 32 therebetween, and three rollers 2, 2' and 2" are arranged between the Sliding plates 3 and 3 stored.

A connecting rod 5 is connected at one end to one end of the sliding plates 3 and 3 by means of screws 4 and 4, and the other end of the connecting rod 5, which extends to the cylinder section 9, is connected to the piston 7 in the cylinder section 9 via a piston pin 6.

A return spring 11 for urging a door 30 in the door closing direction is provided between a spring shoe 33, which is arranged substantially in the longitudinally central portion of the front chamber A, and the end face of the piston 7.

Hydraulic oils 10 and 10' are filled into the front piston chamber A and the rear piston chamber B.

The cylinder portion 9 is formed with a side wall 9a in which a first oil passage 34 and a second oil passage 35 are independently formed so as to communicate with the front chamber A and the rear chamber B, respectively, as shown in Figure 1 and Figures 3 to 8.

The first oil passage 34 has one end in which a front oil passage 17 and a front intermediate oil passage 13 are formed at a predetermined distance in the moving direction of the piston 7 in the cylinder portion 9 so as to communicate with the front chamber A, as shown in Figures 1 and 4. The other end of the first oil passage 34 communicates with the rear chamber B via a rear oil passage 15.

As shown in Figs. 4 to 8, a check adjusting valve 18 is arranged on the front oil passage 17 side of the first oil passage 34 to precisely adjust an oil passage amount. A check valve 14 is arranged between the front intermediate oil passage 13 and the rear oil passage 15 in the first oil passage 34, as shown in Figs. 1 and 4. As shown in Fig. 4, the check valve 14 consists of a valve seat 14a formed in the first oil passage 34 and a ball member 14b, and a screw-like plug 14d is screw-engaged with an opening 34a of the first oil passage 34 in a liquid-tight manner so that the ball member 14b is prevented from being taken out.

The check valve 14 acts so that the hydraulic oil 10 in the front chamber A flows freely into the rear chamber B through the first oil channel 34 when the door is opened, while the hydraulic oil 10' in the rear chamber B does not flow into the front chamber A when the door is closed.

On the other hand, the second oil passage 35 has one end communicating with the front piston chamber A through a front oil passage 25, while the other end communicating with the rear piston chamber B through a rear intermediate oil passage 19 and a rear oil passage 20 formed at a predetermined distance in the direction of movement of the piston 7, as shown in Figures 1 and 3.

As shown in Figure 3, a check valve 23 is arranged on the side of the front oil channel 25 of the front chamber A of the second oil channel 35, which acts in such a way that the the hydraulic oil 10' in the rear chamber B flows freely into the front chamber A through the second oil channel 35 when the door is closed, while the hydraulic oil 10 in the front chamber A does not flow into the rear chamber B when the door is opened. The check valve 23 consists of a valve seat 23a and a ball element 23b.

A first speed adjusting valve 21 and a second speed adjusting valve 22 are arranged near the rear intermediate oil passage 19 and the rear oil passage 20 on the front chamber B side of the second oil passage, as shown in Figs. 3, 5 and 6, so that the amount of oil flowing through can be precisely adjusted.

Figures 9 to 11 show part of a floor door closer according to the invention, which is equipped with mechanisms for effecting a snap-in function to increase the door closing speed shortly before the door is fully closed, in addition to a first and a second speed function and a rebound function.

As shown in Figures 9 to 11, the first oil passage 34 has one end at which a front oil passage 17, a front intermediate oil passage 13 and a rear intermediate oil passage 28 are formed at predetermined intervals in the direction of movement of the piston 7 so as to communicate with the front piston chamber A. A check adjustment valve 18 and a snap-in adjustment valve 27 are formed on the side of the front oil passage 17 and on the side of the rear intermediate oil passage 28, respectively, so that the amount of oil flowing through can be adjusted. In this arrangement, the check valve 14 is further arranged between the front intermediate oil passage 13 and the rear intermediate oil passage 28 in the first oil passage 34. The check valve 14 according to the invention functions in substantially the same manner as described with reference to Figs. 1 to 8. A pressure pin 14c is installed in the first oil passage 34 so as to hold a ball element 14b of the check valve 14 in a predetermined range in a floating state so as not to disturb the smooth flow of the hydraulic oil.

The construction of the floor door closer according to Figures 9 to 11 is essentially the same as that of Figures 1 to 8, so that their details are omitted here.

Figures 12 and 13 show a part of a floor door closer according to a second embodiment of the invention, which is equipped with mechanisms for achieving the deceleration action function for reducing the door closing speed in addition to the first and second speed functions and the back-off function.

As shown in Figs. 12 and 13, a front oil passage 25 and a front intermediate oil passage 26 are formed on the front chamber A side of the second oil passage 35 in place of the rear intermediate oil passage 28 of the second embodiment. In addition, a retardation action adjusting valve 24 is further arranged on the side of the front oil passage 25 as shown in Fig. 13 so as to precisely adjust the oil flow rate.

The further structure of the floor door closer of the second embodiment essentially corresponds to that of Figures 1 to 8, so that its details are omitted here.

Figures 15 to 17 show a part of a floor door closer according to a third embodiment of the invention, which is provided with mechanisms for achieving the deceleration action function and the snap-in action as well as the first and second speed functions and the back-stop function.

As shown in Figs. 15 and 17, a front oil passage 17, a front intermediate oil passage 13 and a rear intermediate oil passage 28 are respectively formed on the front chamber A side of the piston 7 in the first oil passage 34. A check adjusting valve 18 is arranged on the front oil passage 17 side and a snap-action adjusting valve 27 is further arranged on the rear intermediate oil passage 28 side.

On the side of the front chamber A in the second oil passage 35, a front oil passage 25 and a front intermediate oil passage 26 are arranged, respectively, and on the side of the front oil passage 25, a check valve 23 and a retardation action adjusting valve 24 are arranged. The check valve 23 acts in substantially the same manner as described with reference to Figures 1 to 8.

The further construction of the floor door closer according to the third embodiment essentially corresponds to that of Figures 1 to 8, so that its details is now omitted here.

The floor door closer works in the manner described below.

Figures 1 and 2 show the closed state of the door 30, and the lower end of the door 30 is fixed to the main shaft 1 of the floor door closer via an unillustrated arm member or the like. As shown, the piston 7 is held in a position where the piston 7 is moved to the rear chamber B side by the return spring 11, and the rollers 2 and 2' contact the smallest diameter portions of the cam 32.

Assuming that the door 30 is opened in the counterclockwise direction as shown in Figure 18, the main shaft 1 of the floor door closer is rotated in the counterclockwise direction together with the cam 32 as shown in Figure 1, so that the slide plates 3 are moved to the left by the rollers 2 and 2' abutting on the cam 32. Accordingly, the piston 7 moves linearly due to the connecting rod 5 toward the front chamber A side, compressing the return spring 11, so that the piston return force, i.e., the door closing force, is stored in the return spring 11.

According to Figure 18, it is assumed that the opening angle of the door is 120º, the door opening and closing angle in the range of 70º to 120º as the recoil range (BC range), the angle in the range of 120º to 70º as the deceleration operation range (DA range), the angle in the range of 70º to 20º as the first speed range, the angle in the range of 20º to 0º as the second speed range and the angle in the range of 5º to 0º is called the snap-in range (LA range).

Under this assumption, when the door 30 shown in Fig. 18 is opened counterclockwise by angles of 0° to 70° with a suspension base 0 as the center of rotation of the door 30, the hydraulic oil 10 in the front chamber A as shown in Fig. 1 or 2 flows through the front intermediate oil passage 13, the first oil passage 34, the check valve 14 and the rear oil passage 15 into the rear chamber B as shown in Figs. 1, 4 and 7.

When the door 30 is opened at an angle in the BC range as shown in Figure 18, the front intermediate oil passage is closed with a piston sealing surface 16, so that the hydraulic oil 10 in the front chamber A flows into the rear chamber B through the front oil passage 17 of the first oil passage 34, the check valve 14 and the rear oil passage 15. At this moment, the door 30 is subject to the check function because the check adjustment valve 18 is arranged on the side of the front oil passage 17 of the first oil passage 34.

The amount of hydraulic oil 10 displaced is precisely adjusted at this moment by means of the check adjustment valve 18, so that the rapid opening of the door due to, for example, strong wind or a large external force can be prevented.

When the door 30 is closed from the fully opened state, the check valve 14 in the first oil passage 34 is closed by means of the pressure in the rear chamber B. is closed and the hydraulic oil 10' in the rear chamber B thus passes through the second oil channel 35 without passing through the first oil channel 34. Thus, the hydraulic oil 10' in the rear chamber B flows into the front chamber A through the rear intermediate oil channel 19, the rear oil channel 20 in the second oil channel 35, the check valve 23 and the front oil channel 25. At this moment, the amount of the displaced hydraulic oil 10' can be precisely adjusted by means of the first speed adjusting valve 21 and the second speed adjusting valve 22 arranged in the second oil channel 35. Thus, when the door is closed, the door is closed in the range of 70º to 20º at a first speed by controlling the first and second speed adjusting valves 21, 22 and then closed in the range of 20º to 5º by controlling the second speed adjusting valve 22 at a second speed.

In the case where the floor door closer is provided with the snap function described with reference to the first embodiment shown in Figs. 9 to 11, the hydraulic oil 10' in the rear chamber B flows into the front chamber A through the oil passage 15, the snap adjustment valve 27 and the rear intermediate oil passage 25 in the first oil passage 34 in addition to the second oil passage 35 when the door is closed to its fully closed position. Accordingly, when the door 30 is closed with door closing angles in the range of the LA range in Fig. 4, the rear intermediate oil passage 28 is opened by the sealing surface 16a of the piston 7 and the door closing speed is increased and the door can thus be securely closed.

In the case where the floor door closer is equipped with the deceleration action function described with reference to the second embodiment shown in Figs. 12 to 14, the hydraulic oil 10' in the rear chamber B flows into the front chamber A through the rear intermediate oil passage 19, the rear oil passage 20, the first speed adjusting valve 21, the second speed adjusting valve 22, the check valve 23, the deceleration action adjusting valve 24 and the front oil passage 25, all of which are arranged in the second oil passage 35 as shown in Figs. 12 and 13, when the door 30 is closed from the fully opened state with a door closing angle in the range of the DA range.

At this moment, in the DA range, the amount of the displaced hydraulic oil 10' can be precisely adjusted by the first speed adjusting valve 21, the second speed adjusting valve 22 and the deceleration action adjusting valve 24. In this operation, however, in the case that the opening degree of the deceleration action adjusting valve 24 is larger than that of the first and second speed adjusting valves 21 and 22, that is, when the deceleration action function is not achieved, the amount of the hydraulic oil 10' can be precisely adjusted by means of the first speed adjusting valve 21. The door opening angle range that can be adjusted by means of the first speed adjusting valve 21 extends from 120° to 20° as shown in Figure 18. When the door is closed to a position of 70º, the front intermediate oil passage 26 is opened with the retardation action adjusting valve 24 in a non-operating position.

In the third embodiment of the floor door closer, which is shown in Figures 15 to 18, the operation is carried out in a manner completely consistent with that described above with reference to Figures 1 to 14, so that accordingly the details of the operation of the third embodiment are omitted here.

According to the illustrated embodiment of the invention, an ideal door opening and closing operation can be achieved in a suitable combination of the respective functions of the hydraulic line arrangement of the hydraulic control system of the floor door closer.

Claims (5)

1. Hydraulic control system for a door closer with a door closer housing (8) in which a cylinder section (9) is formed in which a piston (7) is moved linearly by a door opening operation against the tension force of a return spring (11), wherein the cylinder section (9) is divided into a front piston chamber (A) and a rear piston chamber (B) by the arrangement of the piston (7), and the door (30) is then automatically closed by the stored return force of the spring (11), wherein the system comprises a check valve device (14, 23) for restricting the flow of the hydraulic oil when the door (30) is opened and closed, a check adjustment valve device (18) for adjusting the speed of the piston (7) in a door opening angle range between a predetermined door opening angle position and a fully opened door angle position and a speed adjustment valve device (21, 22) for Adjusting the speed of the piston (7) in a door closing angle range between a door closing angle position and an approximately closed door angle position, characterized in that the door closer is a floor door closer, that the system further comprises a snap-in device (15, 27, 28) for increasing the speed of the piston (7) from the approximately closed door angle position to a fully closed door position, and that first and second oil channels (34, 35) extending longitudinally on a side wall (9a) of the cylinder portion (9) are independently formed so as to communicate with the rear and front piston chambers (A, B), the first oil channel (34) having a front channel (17) formed in a front portion therein, a rear channel (15) formed in a rear portion therein, and front and rear intermediate channels (13, 28) formed between the front and rear channels (17, 15). wherein a first check valve (14) of the check valve device, which allows hydraulic oil flow only from the front chamber (A) into the rear chamber (B), is provided between the two intermediate channels (13, 28) in the first oil channel (34), and the check adjustment valve device (18) is provided in the front channel (17) of the first oil channel (34), wherein the snap-in device is effective when the rear channel (15) communicates with the rear intermediate channel (28) of the first oil channel (24), wherein the second oil channel (35) has a front channel (25) formed in a front portion therein, a rear channel (20) formed in a rear portion therein, and having a rear intermediate passage (19) formed near the rear passage (20), wherein a second check valve (23) allowing hydraulic oil flow only from the rear chamber (B) into the front chamber (A) is provided in the front passage (25) of the second oil passage (35), and wherein the speed adjusting valve device has two speed adjusting valves, one of which is a first speed adjusting valve (21) arranged in the rear intermediate passage (19) near the rear passage (20) of the second oil passage (35) so as to adjust the speed of the piston (7) from a fully opened door position to a predetermined door closing angle position, and the other of which is a second speed adjusting valve (22) arranged in the rear passage (20) of the second oil passage (35) so as to adjust the speed of the piston (7) from a predetermined door closing angle position to an approximately closed Adjust door angle position. 2. Hydraulic control system according to claim 1, characterized in that the second oil channel (35) further comprises a front intermediate channel (26) which is provided near the front channel (25) in front of the rear intermediate channel (19). 3. Hydraulic control system according to claim 1, characterized in that the check valve (14) arranged in the first oil channel (34) has a valve seat (14a), a ball (14b) and a pressure pin (14c) which is installed in the first oil channel (34) and keeps the ball (14b) in a floating state. 4. Hydraulic control system according to claim 1, characterized in that a snap-in adjustment valve (27) is arranged in the rear intermediate channel (28). 5. Hydraulic control system according to claim 1, characterized in that the check valve (23) in the second oil channel (35) has a valve seat (23a) and a ball (23b).